SECTION 8A2 - LPG SYSTEM

IMPORTANT

Before performing any Service Operation or other procedure described in this Section, refer to Section

00 CAUTIONS AND NOTES for correct workshop practices with regard to safety and/or property damage.

1. GENERAL I NFORMATI O N

Liquefied Petroleum Gas (LPG) Production Option KL7 is available for all VX Series Models with V6 engine and

automatic transmissions.

The system used on VX Series Models is essentially the same as detailed in the VT Series Service Information,

noting the following:

• Software for the Powertrain Control Module (PCM) has been modified, allowing for:

- Deletion of the Adaptive Digital Processor (ADP), thus allowing for theft deterrent functions to be

controlled by the PCM. Also provides a simplified set-up procedure.

- As the PCM used on the VX Series Model is flash programmable, a unique LPG PROM is not required.

- Allows for the switching of fuel modes (LPG to petrol or petrol to LPG) whilst the vehicle is being driven.

- Diagnostic Trouble Code (DTC) support of the LPG system.

• A new Fuel Control Valve (FCV). This valve is the same valve as used for purge control on the GEN III V8

engine and is functionally the same as the FCV used on the VT Series Model.

• Some minor modifications to the routing or hoses and pipes.

• As a running change to VT Series Models LPG was made available (ac c ess or y fitted LPG only) to vehicles with

traction control (ET C). When a vehic le with trac tion c ontrol is oper ated on LPG, trac tion control is disabled and

the TRAC OFF lamp in the instrument cluster is illuminated, warning the driver that traction control has been

disabled.

NOTE: For information not covered in this Section, refer to either the VT Series I Service Information

Sedan LPG system or Wagon and Sedan accessory LPG system.

Figures 8A2-1 (sedan) and 8A2-2 (wagon) show the location of the LPG components used on VX Series Models.

Figures 8A2-3 (sedan) and 8A2-4 (wagon) show the operation of the LPG system. Figure 8A2-5 shows the LPG

System Circuit Diagram.

Figure 8A2-1 SEDAN LPG SYSTEM COMPONENT LOCATIONS

1. LPG Lamp 6. LPG Lock-off

2. Fuel Mode Switch (production fitment) 7. Converter

3. LPG Filler Valve 8. Mixer

4. Solenoid & Manual Service Valve Assembly 9. Fuel Control Valve

5. Powertrain Control Module (PCM)

Figure 8A2-2 WAGON LPG SYSTEM COMPONENT LOCATIONS

1. LPG Lamp 6. LPG Lock-off

2. Fuel Mode Switch 7. Converter

3. LPG Filler Valve 8. Mixer

4. Solenoid & Manual Service Valve Assembly 9. Fuel Control Valve

5. Powertrain Control Module (PCM)

Figure 8A2-3 SEDAN LPG SYSTEM OPERATION - TYPICAL

1. Fuel Mode Switch 16. LPG Lock-off

2. LPG Lamp 17. Mixer

3. Main Wiring Harness 18. Coolant Hoses

4. Body Wiring Harness 19. LPG Filler Valve

5. Powertrain Control Module (PCM) 20. Fuel Control Valve

6. Intermediate Service Line

7. Front Service Line A. Liquid

8. Rear Service Line B. Vapour

9. Filler Line C. Vacuum

10. LPG Cylinder Assembly D. Coolant

11. AFL E. Breather

12. Solenoid & Manual Service Valve Assembly F. Balance / Vacuum

13. Relief Valve G. Air Intake

14. Fuel Gauge H. To Engine Inlet Manifold

15. Converter

Figure 8A2-4 WAGON LPG SYSTEM OPERATION - TYPICAL

1. Fuel Mode Switch 16. LPG Lock-off

2. LPG Lamp 17. Mixer

3. Main Wiring Harness 18. Coolant Hoses

4. Body Wiring Harness 19. LPG Filler Valve

5. Powertrain Control Module (PCM) 20. Fuel Control Valve

6. Intermediate Service Line

7. Front Service Line A. Liquid

8. Rear Service Line B. Vapour

9. Filler Line C. Vacuum

10. LPG Cylinder Assembly D. Coolant

11. Automatic Fill Limiter (AFL) E. Breather

12. Solenoid & Manual Service Valve Assembly F. Balance / Vacuum

13. Relief Valve G. Air Intake

14. Fuel Gauge H. To Engine Inlet Manifold

15. Converter

VXPCM021

INSTRUMENT

PCM

LPG

LAMP

BATTERY POWER

IGNITION

IGN ITIO N SWITCH

BATTERY

O/B (740) O (740)

R (2H)

(1040)

15a 15 50

30 ACC

IGN

START

F21

F13

F14

P (3)

Y/G

CONTROL

SIGNAL

2-3mA

B/Y

P/G

30V

W/G

B/R

BLU/R

LPG

TANK

SENDER

SMART UNIT

LPG

SENDER

FUEL

GAUGE

W/G (937) A3

LPG

ENABLE

EARTH

FUEL MODE SW ITCH

LPG FCV

LPG WIRING

CONFIGURATION

BATTERY

IGNITION

SERIAL

DATA

G / W (122 0) R/B (1 221) C13 SERIAL

DATA

12V

P/B (39)

O/Y (1340)

Y (1030)

P/BLU (44)

F31

O (740)

P (39)

P (39)P/B (39)

GY /B (1 4 13)

G/Y (1412)

RIGHT HAN D

OXYGEN SENSOR

RH O2

SIGNAL LO

RH O2

SIGNAL HI

450 mV

B/ R (7 5 0)

LOC. E 4

LOC. E 3

LOC. E 5/E15

LOC.

E5 LOC.

E15

B (155)

B/ Y

(155)

B/Y (155)

BCM

LOC. E1

Figure 8A2-5 LPG System Circuit Diagram

2. PRINCIPLES OF OPERATION

NOTE: Excluding the following, principles of

operation for the LPG system used on VX Series

Models are as detailed in the VT Series I Service

Information – VT Sedan with Production LPG and

VT Sedan with Accessory LPG and VT Wagon.

2.1 FUEL CONTROL VALVE

A new type of Fuel Control Valve (FCV) is used on

VX Series Models.

The Fuel Control Valve (FCV) is used to control

fuel delivery. Because the diaphragm of the

converter is very large, little movement is required

to control the amount of LPG delivered. The fuel

control valve is connected into the balance line

between the atmospheric vent of the converter

secondary diaphragm and the air valve venturi of

the mixer. This applies a very low vacuum to the

atmospheric side of the converter secondary

diaphragm. Any pressure less than atmospheric

results in a reduction in LPG delivery. This ass ures

extremely accurate LPG delivery and rapid

response time.

With the exhaust gas oxygen sensor at operating

temperature and the Powertrain Control Module

(PCM) operating in closed loop mode, there is a

wide range of control. This permits the PCM to

optimise the air/fuel mixture to varying engine

requirements.

The FCV is controlled by the PCM. To open the

FCV and decrease the pressure acting on the

secondary diaphragm of the converter, the PCM

pulses the FCV on and off at a frequency of 10Hz.

The ratio between the on and off time is called the

duty cycle. To open the FCV the PCM increases

the duty cycle, which decreases the pressure

applied to the secondary diaphragm. The amount

of time the FCV is on will determine the pressure

acting on the converter secondary diaphragm. In

this way, the PCM can control the air/fuel ratio.

Figure 8A2-6 Fuel Control Valve Assembly

1. Vacuum inlet 4. Coil

2. Vacuum outlet (to converter) 5. Plunger assembly

3. Coil terminals

Figure 8A2-7 Fuel control valve operation

1. FCV

2. Vacuum inlet

3. Balance hose

4. Secondary diaphragm

5. Converter

6. Regulator check valve

A. Vacuum from mixer

2.2 FUEL MODE S WITCH

On all vehicles fitted with an LPG system, the fuel

mode switch is m ounted in the centre cons ole. The

switch is a momentary contact type switch.

When the fuel mode switch is pressed, the switch

supplies 12 volts to PCM terminal F4. The PCM

sees this voltage as a request to change over from

petrol to LPG or from LPG to petrol.

NOTE: The PCM will only toggle between the

petrol and LPG mode if the ignition is on and

the engine is not running, or if the engine

speed is greater that 1300 RPM.

The operational mode of the PCM in is stored in the

PCM m em ory so that the engine s tarts in the sam e

mode on the next ignition cycle.

Figure 8A2-8 Fuel mode switch

2.3 TRACTION CONTROL (ETC) OPERATION

Whenever the vehicle is operating in the LPG

mode, the traction control system (if fitted) is

disabled and the TRAC OFF warning lamp in the

instrument cluster is illuminated, warning the driver

that the traction control system (ETC) has been

disabled.

The tr action c ontr ol system is disabled by the PCM,

which sends a message to the ABS/ETC control

module via the serial data circuit, requesting the

traction control system be switched off.

Figure 8A2-9

2.4 POWERTRAIN CONTROL MODULE

The Powertrain Control Module (PCM) when

programmed with the correct LPG calibration is

capable of operating in either of two operating

modes, PETROL or LPG.

PETROL MODE

W hen operating in petrol m ode, the LPG system is

turned off and the vehicle operates on petrol with

full engine management control in the same

manner as a vehicle not fitted with LPG. In this

mode, the instrument cluster fuel gauge will show

the amount of petrol in the petrol fuel tank.

LPG MODE

When operating in the LPG mode, the engine

managem ent sys tem is s witched to LPG m ode and

the LPG system is turned on, enabling the vehicle

to operate on LPG. In this mode the LPG lam p will

be turned on and the instrument cluster fuel gauge

will show the amount of LPG in the LPG cylinder.

The PCM controls the flow of LPG, by sending a

signal to the smart unit via circ uit 937 W/G wire. On

receiving this signal the smart unit energises the

solenoid valve. The smart unit also energises the

LPG lock-off via circuit 965 BLU/Y wire.

Figure 8A2-10

NOTE: In the LPG mode, the following changes

have been made so the engine can operate on

LPG. These changes only effect the operation of

the PCM when operating in LPG mode.

INJECTOR PULSE WIDTH

The injector pulse width is set to zero in all LPG operating modes, except during engine cranking or, on when the

vehicle runs in “engine valve recession protection mode”.

During engine cranking the amount of petrol delivered is determined by the engine coolant temperature and the

engine crank time. The injection of petrol during engine cranking is to aid engine starting. If the engine stalls no

petrol will be injected during cranking, unless the ignition is cycled off and on.

When operating in LPG mode under conditions of prolonged high speed / high load, a small amount of petrol is

injected into the engine to cool the valves and catalytic converter.

FUEL PUMP

To pr ovide petrol when starting in the LPG m ode, the fuel pum p will r un for two sec onds when the ignition is turned

to the ON position and continue to run when the engine is being cranked, but will be turned off five seconds after the

engine starts.

The fuel pump will also operate under high load conditions. This allows for petrol to be injected into the engine when

the vehicle goes into the engine valve recession protection mode.

As a protection devise to the fuel pump, the PCM will switch off the fuel pump and disable the engine valve seat

recess ion protec tion m ode, if there is less than s ix litres of f uel in the petrol tank . T he PCM m onitors the s erial data

normal mode message to determine the amount of fuel in the petrol tank.

ELECTRONIC SPARK TIMING

A specif ic Electronic Spark T iming ( EST) m ap is used when in the LPG mode and the PCM has been progr amm ed

to provide optimum EST f or LPG oper ation. If the engine speed dr ops below 300 RPM, the PCM prevents the s par k

plugs from firing by setting the ignition dwell to zero.

FUEL USAGE SIGNAL OUTPUT

The PCM fuel us age output signal is us ed by the trip computer to deter m ine the fuel cons um ption display and is re-

calibrated to suit LPG.

ENGINE CRANKING

If the throttle opening is greater than 7% when operating in LPG mode, the PCM will prevent the engine from

cranking by not energising the starter relay.

3. SERVICE OPERATIONS

Service Operations for the LPG system used on VX Series Models are as detailed in the VT Series I Service

Information, VT Sedan with Production LPG or VT Sedan with Accessory LPG and VT Wagon.

NOTE 1: Some components used on VT Series Models are not required on VX Series Models, i.e. ADP control

module, LPG diagnostic interconnect diagnostic connector and the LPG relay.

NOTE 2: Some of the Service Operations detailed for the VX Series LPG system are identical for the VT Series

however, pictorially, some illustrations shown in the VT Series Service Manual may differ slightly. Only where

significant differences exist or where the illustration has a significant bearing on the particular Service Operation, will

the Service Operation be republished.

3.1 CONVE RTE R

CONVERTER ON VEHICLE TEST PROCEDURE

(REFER TO FIGURE 8A2-13)

1. Park the vehicle in a well ventilated area, away

from any ignition source.

2. Drain the service lines of LPG, refer to

Section 2 SERVICE OPERATIONS

in the VT Series I Service Information,

VT Sedan with Production LPG or

VT Sedan with Accessory LPG and

VT Wagon.

3. Ensure the manual service valve is turned

'OFF' and the battery earth lead is

disconnected.

4. Remove plug from the converter primary test

port (5) and install straight test nipple into

converter primary test port.

5. Connect the pressure gauge hose to the

straight nipple and to the HI connection of the

0-5 PSID pressure gauge of LPG test kit (refer

to Section 7 SPECIAL TOOLS).

6. Remove plug from the converter secondary

test port (12) and install test elbow into

secondary test port.

7. Connect vac uum gauge hos e to sec ondary test

elbow and the LO connection of 0-10 INCHES

W.C. vacuum gauge LPG test kit 1.

8. Turn 'ON' manual service valve and check test

connections for leaks.

9. With fuel mode switch in LPG position start

engine and allow to idle.

NOTE: If engine will not star t, crank the engine and

record pressures.

10. Converter primary pressure should be 1.0-1.5

psi (7-10 kPa).

11. Disconnect FCV to converter balance lines at

converter.

12. Secondary converter pressure should be

negative 1-1.5 inches W.C. (negative 24-38

mm W.C.).

13. Reconnect balance line and secondary

pressure gauge should fluctuate from 1 - 5

inches W.C. (24-38 mm W.C.)

14. Turn 'OFF' engine, gauges should hold

pressure for at least five minutes.

Figure 8A2-11

Figure 8A2-12

Figure 8A2-13

1. Inches W.C. gauge

(secondary pressure)

2. Low port

3. PSID gauge (primary pressure)

4. High port

5. Primary pressure port

6. Straight test nipple

7. Vapour hose

8. Test elbow

9. Water drain

10. Balance hose (to mixer)

11. Balance hose (to FSV)

12. Secondary pressure port

REMOVE

1. Park the vehicle in a well ventilated area, away

from any ignition source.

2. Drain the service lines of LPG, refer to

Section 2 SERVICE OPERATIONS in the

VT Series I Service Information,

VT Sedan with Production LPG or

VT Sedan with Accessory LPG and

VT Wagon.

3. Ensure the manual service valve is turned

'OFF' and the battery earth lead is

disconnected.

4. Depressurise engine cooling system by

removing radiator cap in two stages.

CAUTION: DO NOT REMOVE RADIATOR CAP

WHILE T HE ENGINE COOLANT TEM PERAT URE

IS ABOVE 50oC AS PERSONAL INJURY MAY

RESULT.

Figure 8A2-14

Figure 8A2-15

5. Place drain tray beneath vehicle. Loosen

clamps (1) securing engine coolant hoses (2)

to converter coolant inlet and outlet elbows.

Remove coolant hoses from converter and lay

back away from converter.

Figure 8A2-16

6. Disconnect LPG-off harness connector (1) from

LPG lock-off (2).

Figure 8A2-17

7. Loosen and disconnect front service line (1)

from the LPG lock-off inlet connection (2).

Figure 8A2-18

8. Remove the two screws (1) securing the

converter heat shield (2) to the converter (3)

and remove heat shield.

Figure 8A2-19

9. Remove FCV balance hose (1) and vacuum

hose (4) from converter connections.

10. Loosen mixer to converter vapour hose clamp

(2) at converter vapour outlet and disconnect

vapour hose (3) from converter.

Figure 8A2-20

11. Loosen and remove the two heat shield support

bolts (1) (2 places) and the converter retaining

bolt (2).

12. Remove converter assembly (3).

13. Rem ove engine coolant inlet and outlet elbows,

vapour outlet, FCV balance hose connection

and lock-off assembly if required.

If carrying out the following overhaul procedure

on the converter assembly, loosen and

unscrew the LPG lock-off to converter

connection, remove the connection and LPG

lock-off from the converter.

Figure 8A2-21

OVERHAUL

The proc edure f or overhauling the c onverter is as detailed in Sectio n 2 SERVICE OPERATIONS in the VT Series I

Service Information – VT sedan with Production LPG.

CONVERTER OFF VEHICLE TEST

With the converter removed from the vehicle, proceed as follows:

1. Rem ove plug from the converter prim ary test point and ins tall straight test nipple (1) into converter primar y test

point (2) .

2. Connect the pressure gauge hose (3) to the straight test nipple and to the high connection of the of the

0 - 5 PSID pressure gauge (4) of LPG test kit 1.

3. Remove plug from the converter secondary test point and install test elbow (5) into secondary test point (6).

4. Connect vacuum gauge hose (7) to test elbow and the 'LOW' connection of 0 - 10 INCHES W.C. vacuum

gauge (8) of LPG test kit 1.

5. Remove converter to LPG lock-off connector (9) from LPG lock-off and reinstall into converter. Tighten

connector securely.

6. Connect an air supply (10) into the converter to LPG lock-off connector and adjust air supply pressure to 875

kPa (125 psi).

7. Note the pressure reading on the primary pressure gauge. Primary converter pressure should be 7 - 10 kPa

(1.0 - 1.5 psi).

8. Disconnect air supply, The converter should hold primary pressure for at least five minutes.

NOTE: The following step involves the use of a domestic vacuum cleaner as a vacuum source.

9. Reconnect regulated air s upply to the converter to LPG lock-of f c onnec tor. While watching the primary pressure

gauge, bring the vacuum nozzle of the vacuum cleaner (11) to the converter vapour outlet (12). When the

primary pressure gauge needle moves (indicating start point of vapour supply out of secondary), note and

record the secondary vacuum gauge reading.

Secondary converter pressure should be negative 1 - 1.5 inches W.C. (negative 24 - 38 mm W.C.).

If during this test the specified primary and/or secondary pressures cannot be achieved, the converter must be

overhauled.

Figure 8A2-22

REINSTALL

Reinstallation of the converter is the reverse of the removal procedure, noting the following points:

1. If rem oved, ens ure that the engine coolant inlet and outlet elbows, vapour outlet, FCV balance hos e connection

threads and converter mating threads are clean.

Apply Loctite 567 sealant to coolant and vapour elbow threads and tighten these elbows to positions shown in

Figure 8A2-23.

2. Ensure that the LPG lock -off to converter connector and front service line to lock-of f connector mating threads

are clean.

If removed, also clean LPG lock-off connector and LPG lock-off mating threads.

Apply Loctite 577 sealant to LPG lock-off connector ensuring that flared surfaces are free of sealant and

contaminants. Install LPG lock-off connector to LPG lock-off and tighten securely.

Install LPG loc k-of f to the conver ter and tighten securely and if necess ary, further tighten it s o as to align it with

the retaining bracket.

Figure 8A2-23

1. Converter

2. Vapour outlet elbow

3. FCV balance hose connector

4. Nipple

5. Coolant elbow

6. LPG lock-off

7. Connector

8. Coolant elbow

A. Front of vehicle

3. Tighten all fasteners to the correct torque

specification

LOCK-OFF BRACKET TO

CONVERTE RATTACHI NG SCREW

TORQUE SPECIFICATION

3.0 - 5.0 Nm

CONVERTE R RE T AINING BOLT T O

SUPPORT BRACKET

TORQUE SPECIFICATION

10.0 - 12.0 Nm

HEAT SHIELD SUPPORT BOLT TO

SUPPORT BRACKET

TORQUE SPECIFICATION

10.0 - 12.0 Nm

HEAT SHIELD RETAINING SCREW

TO HEAT SHIELD SUPPORT BOLT

TORQUE SPECIFICATION

3.0 - 5.0 Nm

4. Apply Loctite 577 to lock-off connector and

tighten front service line to LPG lock-off

connector to the correct torque specification.

FRONT SERVICE LI NE CONNECTOR

TO LPG LOCK-OFF

TORQUE SPECIFICATION

12.0 - 15.0 Nm

5. Leak test LPG system, refer to

Section 2 SERVICE OPERATIONS in the

VT Series I Service Information –

VT Sedan with Production LPG and

VT Sedan with Accessory LPG and

VT Wagon.

6. Refill cooling system with coolant to the

correct concentration level, refer to

2.3, CHECKING AND FILLING COOLING

SYSTEM, and pressure test the system, refer

2.7, PRESSURE TESTING in the VT Series I

Service Information Section 6B1 ENGINE

COOLING.

3.2 REGULATOR CHECK VALVE (RCV)

TEST

1. Connect TECH 2 to the DLC.

1. DLC

2. DLC Adaptor

3. DLC Cable

4. TECH 2

NOTE: For additional information on connecting

and operating TECH 2, refer to

Section 0C TECH 2 in the VX Series Service

Information.

2. Select: Diagnostics / Appropriate Model Year /

VX Commodore / Engine / V6 / Turn the

ignition as instructed by TECH 2 and confirm

the System Identification / Data Display / All

Data.

3. Scroll to LPG FCV Duty Cycle.

4. Start the engine and take note of the duty

cycles displayed on the TECH 2 screen for the

FCV.

Figure 8A2-24

5. Place a finger over the RCV (1) atmospheric

port (large opening Figure 8A2-25.) and take

note of the FCV duty cycles.

There should be little or no change in the duty

cycle.

6. Place a 3/8” inside diameter hose over the

RCV atm ospheric port (large opening). Apply a

sm all amount of air pr es su re to the open end of

the hose (physically blow through hose) and

take note of the duty cycles displayed for the

FCV.

If duty cycles do not change, it indicates the

RCV is not opening as required and should be

replaced.

Figure 8A2-25

REMOVE

1. Park the vehicle in a well ventilated area, away

from any ignition source.

2. Drain the service lines of LPG, refer to

Section 2 SERVICE OPERATIONS in the

VT Series I Service Information,

VT Sedan with Production LPG or

VT Sedan with Accessory LPG and

VT Wagon.

3. Ensure the manual service valve is turned

'OFF' and the battery earth lead is

disconnected.

Figure 8A2-26

Figure 8A2-27

4. If necessary, remove the two screws securing

the heat shield to the converter heat shield

support bolts and remove heat shield.

5. Unscrew the RCV from the converter.

REINSTALL

Reinstallation of the RCV is the reverse of the

removal procedure, noting the following.

Apply Loctite 567 sealant to RCV threads, install

RCV to the converter and tighten securely and if

necessary, further tighten it so as to align it as

shown in shown in Figure 8A2-28.

Figure 8A2-28

3.3 FUEL CONTROL VALVE

REMOVE

1. Park the vehicle in a well ventilated area, away

from any ignition source.

2. Drain the service lines of LPG, refer to

Section 2 SERVICE OPERATIONS in the

VT Series I Service Information,

VT Sedan with Production LPG or

VT Sedan with Accessory LPG and

VT Wagon.

3. Ensure the manual service valve is turned

'OFF' and the battery earth lead is

disconnected.

Figure 8A2-29

Figure 8A2-30

4. Using a flat bladed screwdriver, gently lever the

retaining tang on the FCV retaining bracket (2)

towards the rear of the vehicle and slide the

FCV (1) outwards.

5. With the FCV removed from the retaining

bracket, disconnect the wiring harness

connector, remove the balance and vacuum

hoses from the FCV. Remove FCV from

vehicle.

Figure 8A2-31

TEST

1. Connect an Ohm m eter to coil term inals of FCV

(1), refer to Figure 8A2-32.

If the coil resistance of the FCV is not as

specified, the fuel control valve should be

replaced.

FUEL CONTROL VALVE COIL 19 - 21 OHMS

RESISTANCE @ 20°C

Figure 8A2-32

2. Connect a vacuum pump (1) such as Tool No.

J23738-A, to the vacuum connector of the

fuel control valve assembly (2), refer

Figure 8A2-33.

3. Operate the vacuum pump until 15 inches Hg.

(50 kPa) of vacuum is applied to the FCV.

Figure 8A2-33

4. Note the time tak en for the vacuum to bleed of f

through the FCV.

If 15 inc hes Hg. (50 kPa) of vacuum c annot be

created, or the bleed of f tim e is less than three

to five seconds, then the FCV should be

replaced.

Figure 8A2-34

5. Using appropriate tes t leads (2) (suc h as those

found in KM-609) and connect 12 volts (vehic le

battery) to the FCV coil terminals (1), refer

Figure 8A2-35.

If the valve does not open (should be heard to

click as 12 volts applied – can blow through

FCV valve with 12 volts applied), the fuel

control valve should be replaced.

Figure 8A2-35

REINSTALL

Reinstallation of the FCV is the reverse of the

removal procedure noting the following:

1. Ensure FCV balance and vacuum hoses are

routed correctly, refer to Figure 8A2- 36.

2. Connect LPG wiring harness connector to FCV,

ensuring that it is routed correctly, refer Figure

8A2-36.

Figure 8A2-36

1. Balance hose (Atmospheric) 2. Vacuum hose 4. Breather hose

1A. Balance hose (Vacuum) 3. FCV wiring harness connector

3.4 MIXER

TEST

1. Park the vehicle in a well ventilated area, away

from any ignition source.

2. Drain the service lines of LPG, refer to

Section 2 SERVICE OPERATIONS in the

VT Series I Service Information,

VT Sedan with Production LPG or

VT Sedan with Accessory LPG and

VT Wagon.

3. Ensure the manual service valve is turned

'OFF'.

4. Disconnect the Mass Air Flow Sensor

connector YE100.

5. With the Petrol mode selected via the fuel

mode switch, start the engine and allow to idle

until the Check Powertrain Lamp is illuminated,

then turn the engine ‘OFF’

NOTE: Running the engine with the Mass Air Flow

Sensor connector YE100 disconnected will cause

DTC P0101 to set. Setting DTC P0101 will allow

the engine to start with the air duct removed as

described in Step 8 of this procedure.

Figure 8A2-37

Figure 8A2-38

6. Loosen clamps (1) on either end of air duct

boot (2), between mixer and Mass Air Flow

Sensor, remove air duct boot.

Figure 8A2-39

7. Loosen and remove bell housing to air valve

cover attaching bolt (1) and separate bell

housing (2) and gasket (3) from mixer body (4).

Figure 8A2-40

8. With the Petrol mode selected via the fuel

mode switch, start engine and allow to idle.

9. Observe mixer diaphragm position. Diaphragm

should lift slightly (A) as engine is cranked.

Also, diaphragm lift should increase as engine

RPM is increased.

10. If diaphragm does not lift as RPM increases,

check for vacuum leaks between mixer and

throttle body. If no vacuum leaks, overhaul

mixer, refer MIXER-OVERHAUL in the

VT Series I Service Information,

VT Sedan with Production LPG or

VT Sedan with Accessory LPG and

VT Wagon.

Figure 8A2-41

11. Reinstall bell housing gasket (3) bell housing

(2) and the bell housing to air valve cover

attaching bolt (1) and tighten to the correct

torque specification.

12. Reinstall air duct and tighten air duct clamps

refer Figure 8A2-39 and tighten to correct

torque specification.

13. Clear all DTC’s using Tech 2.

BELL HOUSING TO AIR

VALVE COVER ATTACHING 1.0 – 3.0 Nm

BOLT TORQUE SPECIFICATION

AIR DUCT CLAMPS 1.5 – 2.5 Nm

Figure 8A2-42

REMOVE

1. Park the vehicle in a well ventilated area, away

from any ignition source.

14. 2. Drain the service lines of LPG, refer to

Section 2 SERVICE OPERATIONS in the

VT Series I Service Information,

VT Sedan with Production LPG or

VT Sedan with Accessory LPG and

VT Wagon.

3. Ensure the manual service valve is turned

'OFF' and the battery earth lead is

disconnected.

Figure 8A2-43

Figure 8A2-44

4. Remove the Fuel Control Valve (FCV) from

the mixer assembly, refer to

3.3 FUEL CONTROL VALVE in this Section.

5. Loosen clamps (1) on either end of air duct

boot (2), between mixer and MAF sensor,

remove air duct boot.

Figure 8A2-45

6. Remove the F CV vacuum s upply hose (1) from

the mixer (2).

7. Disconnect the crankcase breather hose (3)

from the mixer assembly connector.

Figure 8A2-46

8. Loosen the adaptor hose clamp (1) at the mixer

end (2).

Pull the mixer from the adaptor hose (3).

9. Loosen vapour hose to mixer inlet clamp (4),

disconnect vapour hose (5) and remove mixer.

Figure 8A2-47

OVERHAUL

15. The procedure for overhauling the mixer is as

detailed in Section 2 SERVICE OPERAT IONS in

the VT Series I Service Information,

VT Sedan with Production LPG or

VT Sedan with Accessory LPG and

VT Wagon.

REINSTALL

Reinstallation of the mixer is the reverse of the

removal procedure noting the following point:

1. Ensure FCV balance and vacuum hoses are

routed correctly, refer to Figure 8A2-48.

2. Connect LPG wiring harness connector to FCV,

ensuring that it is routed correctly, refer Figure

8A2-48.

Figure 8A2-48

1. Balance hose (Atmospheric) 2. Vacuum hose 4. Breather hose

1A. Balance hose (Vacuum) 3. FCV wiring harness connector

3.5 LPG SE TUP PROCEDURE

NOTE: The following LPG Setup Procedures

must be carried out when any LPG system

component (mixer, converter, FCV or PCM) has

been replaced, overhauled, reprogrammed, or

when the engine assembly has been replaced or

overhauled.

The LPG Setup procedure allows you to adjust the

idle mixture under controlled conditions, these

conditions are:

Short and Long Term Fuel Trim Cells set to zero.

Fixed Spark advance.

Fixed idle air control valve steps.

Fuel control valve duty cycle fixed at 40%.

1. Connect TECH 2 to the DLC.

1. DLC

2. DLC Adaptor

3. DLC Cable

4. TECH 2

2. With the LPG mode selected, start the engine

and with no load on the engine, air conditioning

off (if fitted), all electrical consumers turned off

and park position selected, allow engine and

oxygen sensor to reach operating temperature.

Figure 8A2-49

3. Select: Diagnostics / Appropriate Model Year

(1) 2001 / VX Commodore / Engine / V6 /

Function Tests/ LPG Setup.

During the setup pr ocedur e Tech 2 ensur es the

follow engine operating conditions are met and

maintained.

Engine Coolant Temperature greater than 91°C

Operating in closed loop.

Right hand oxygen senor is ready.

The engine cooling fan is off

(engine coolant temperature less than 104°C).

Once all the preconditions have been met,

Tech 2 will display the Right O2 Sensor Voltage

and Status.

Engine

LPG Se tup

Right O2 Sensor

Righ t O2 Status 500 mV

Rich

VXLPG001

Confirm

Figure 8A2-50

4. Adjust the idle mixture screw until the right

hand oxygen sensor voltage is as close to 500

mV as possible and the status of the right O2

Sensor is constantly toggling between rich and

lean.

Oxygen sensor voltages greater than 500 mV

indicates a rich mixture turn the idle mixture

screw anti-clockwise to lean off the mixture.

Oxygen sensor voltages less than 500 mV

indicates a lean mixture turn the idle mixture

screw clockwise to richen the mixture.

If the engine coolant temperature exceeds

104°C the engine cooling fan will be turned on

and Tech 2 will suspend the setup procedure,

when the engine cools down and the cooling

fan is turned off, Tech 2 will continue with the

setup procedure.

Figure 8A2-51

3.6 LPG FUEL CONTROL VALVE TEST

The LPG Fuel Control Valve Test is used to

command the LPG Fuel Control Valve from 10% to

90% in steps of 10%.

1. Connect TECH 2 to the DLC.

1. DLC

2. DLC Adaptor

3. DLC Cable

4. TECH 2

Figure 8A2-52

2. Select: Diagnostics / Appropriate Model Year

(1) 2001 / VX Commodore / Engine / V6 /

Miscellaneous Tests/ LPG Fuel Control Valve

Test.

M isc ellaneou s Tes ts

VXLPG005

F0 : Output Tes ts

F1 : IAC System

F2: EGR Co ntrol

F3: Re se t Ce lls

F4 : B ypass Spark

F5 : Air Fuel Ra tio

F6: LPG Fuel Control Valve Test

F7 : LPG Enable

Figure 8A2-53

3. With the LPG mode selected, start the engine

and allow the engine to idle.

4. The FCV duty cycle can be increased and

decreased using the decrease or increase soft

keys. Increasing the duty cycle will cause a

leaner air fuel ratio, decreasing the duty cycle

will cause a richer air fuel ratio.

NOTE: The FCV can only be commanded if the

engine is running in the LPG mode.

LPG Fuel C ontrol Valve

(1) 2001 V X Commodore

Engine: V6

Engine Speed

Des ired En gine Idle Spe

EC T S ens or (E ng ine Coo l

Co olant Temp era tu re

IAT Se nso r (Intake A ir

Intake Air Temp eratu re

M AF S ens or (Ma ss Air Fl

833

825

1.25

2.45

2730

RPM

LPG Fuel C ontrol Valve

VX0C051

Quit Decrease Increase

1 / 85

45 %

Figure 8A2-54

3.7 LPG ENABLE TEST

The LPG Enable Test is used to enable the LPG

operating mode. When commanded on the PCM

will switch to the LPG operating mode, when

commanded off the PCM will switch to the Petrol

operating mode, refer following note.

NOTE: The PCM will only toggle between the Petrol

and LPG m ode if the ignition is on and the engine is

not running or if the engine speed is greater that

1300 RPM.

1. Connect TECH 2 to the DLC.

1. DLC

2. DLC Adaptor

3. DLC Cable

4. TECH 2

Figure 8A2-55

2. Select: Diagnostics / Model Year (1) 2001 /

VX Commodore / Engine / V6 / Miscellaneous

Tests/ LPG Enable Test.

M isc ellaneou s Tes ts

VXLPG006

F0 : Output Tes ts

F1 : IAC System

F2: EGR Co ntrol

F3: Re se t Ce lls

F4 : B ypass Spark

F5 : Air Fuel Ra tio

F6: LPG Fuel Control Valve Test

F7 : LPG Enable

Figure 8A2-56

4. With the ignition on and the engine not

operating or with the engine operating above

1300 RPM, the LPG mode can then be

commanded On or Off using the ON and Off

soft keys. When commanded On the PCM will

switch to the LPG mode, when c omm anded Of f

the PCM will switch to the Petrol Mode.

LPG Enable

(1) 2001 V X Commodore

Engine: V6

Engine Speed

Des ired En gine Idle Spe

EC T S ens or (E ng ine Coo l

Co olant Temp era tu re

IAT Se nso r (Intake A ir

Intake Air Temp eratu re

M AF S ens or (Ma ss Air Fl

833

825

1.25

2.45

2730

RPM

LPG M ode Enabled

VX0C052

Quit Off On

1 / 85

Yes

Figure 8A2-57

4. DIAGNOSIS

4.1 PREREQUISITES TO DIAGNOSIS AND TROUBLESHOOTING

PRELIMINARY SYSTEM REQUIREMENTS

The prerequisites before proceeding with system checks are:

• Ensure that sound ear th connections are available for all f unctioning com ponents, par ticularly at the body earth

connection (fender panel inner stud, adjacent to the battery).

• Ensure the battery is in good condition and adequately charged (above 12.5 volts) before carrying out any

electrical checks.

SAFETY REQUIREMENTS

Disconnect the battery when carrying out work which involves the risk of an electrical short circuit.

Do not touch mechanical components during function checks, to avoid the risk of a hand being caught in the

mechanism.

All Safety Standards and Regulations pertaining to LPG must be followed at all times.

CHECKING EQUIPMENT

Tech 2 scan tool.

A digital multimeter, with a minimum 10 Megohm impedance MUST be used when undertaking any electrical

checks on these systems.

Exercise care when taking readings from wiring harness connectors. It is preferred that the back probing method

with individual connectors is employed wherever possible, to avoid terminal damage and subsequent connection

failure.

When carrying out wiring c hec k s as direc ted to by the diagnostic charts, rather than probe terminals and connectors

with incorrec t sized multim eter connec tions, use the adaptors contained in connector test adaptor kit KM-609. This

will prevent any possibility of spreading or damaging wiring harness terminals.

IMPORTANT:

• ENSURE THAT THE IGNITION IS TURNED OFF AND THE BATTERY EARTH LEAD IS DISCONNECTED

BEFORE ANY TEST THAT REQUIRES DISCONNECTION OR RECONNECTION OF ANY CONTROL

MODULE CONNECTORS.

• When checking the complete sy stem, the exact order of the test steps should be observed.

• If the requir ed nominal value is not ac hieved in any stage, then the problem must be rec tif ied before proc eeding

further.

• Unless the multimeter being used has an auto ranging function, check that the correct range, as specified, is

selected before the test is carried out.

• Testing of the system will involve gaining access to specific wiring harness connectors. For the location of

connectors not detailed in this Section, refer to Section 12N FUSES AND WIRING HARNESSES in the VX

Series Service Information.

4.2 GENERAL INFORMATION

The procedures outlined in the LPG VEHICLE PRELIMINARY DIAGNOSTIC CHART MUST be carried out

first whenever diagnosing a problem in a LPG vehicle.

The LPG system is designed to operate in LPG mode when LPG has been selected via the fuel mode switch. When

diagnosing the LPG system , unless other wise directed. Ens ure that the LPG m ode has been selected, there is LPG

in the LPG cylinder and the manual service valve is turned 'ON'.

When LPG has been selected via the fuel mode switch the PCM will operate in the LPG mode if the operating

parameters sensed by the PCM permit the switching to the LPG mode.

Before any diagnostic procedures are carried out on the LPG system you must first confirm that the vehicle

operates on petrol without any problems.

4.3 LPG VEHICLE PRELIMINARY DIAGNOSIS

TEST DESCRIPTION

The numbers below refer to step numbers in the following diagnostic chart.

1. If the Check Powertrain Lam p illum inates the PCM is being powered up. If the Check Powertrain Lam p does not

illuminate you should refer to the ON-BOARD DIAGNOSTIC SYSTEM CHECK, Section 6C1 in this Service

Information.

2. Ensures Tech 2 is functioning correctly.

3. Checks if Tech 2 can communicate with the PCM.

4. Checks if any PCM DTCs are present.

5. Checks if the PCM can operate in the LPG mode.

6. Checks if the LPG switch is operating correctly.

7. Checks the operation of the LPG lamp.

8. Checks if the engine will operate on petrol.

9. Checks if the engine will crank when LPG has been selected.

10. Checks if the engine will run when LPG has been selected.

STEP ACTION YES NO

1. 1. Turn ignition on.

2. Does the Check Powertrain Lamp illuminate for at

least two seconds?

Go to Step 2. Refer ON-BOARD

DIAGNOSTIC SYSTEM

CHECK, Section 6C1 in

this Service Information.

2. 1. Turn ignition off, install Tech 2 to DLC, turn ignition

on and turn on Tech 2.

2. Does Tech 2 power up (screen will illuminate and

display Tech 2)?

Go to Step 3. Refer Tech 2

DIAGNOSIS, Section

0C Tech 2 in this

Service Information.

3. 1. With Tech 2 still connected and ignition on, press

the ENTER key then select Diagnostics / (1) 2001 /

VX Commodore / F0: Engine / V6 and then follow

the screen instructions.

2. Does Tech 2 display PCM system identification

information?

Go to Step 4. Refer ON-BOARD

DIAGNOSTIC SYSTEM

CHECK, Section 6C1 in

this Service Information.

4. 1. At the Tech 2 PCM System Identification screen

Press the Confirm Soft key, from the Engine

application menu select F1: Diagnostic Trouble

Codes / Read Current DTC.

2. Are any DTCs present?

Refer ON-BOARD

DIAGNOSTIC SYSTEM

CHECK, Section 6C1 in this

Service Information.

Go to Step 5.

5. 1. Return to the Tech 2 Engine application menu and

select / F2: Data Display / F0: All Data / Scroll to

“LPG Fuel Enabled”.

2. Does Tech 2 display LPG Fuel Enabled YES?

Go to Step 6. Refer 4.4 DOES NOT

OPERATE ON LPG, in

this Section.

6. 1. With Tech 2 still connected, scroll to “Fuel”.

2. Select LPG via the fuel mode switch.

3. Does Tech 2 Data parameter “Fuel” change from

Petrol to LPG?

Go to Step 7. Refer 4.5 FUEL MODE

SWITCH DOES NOT

OPERATE, in this

Section.

7. 1. With the LPG Mode selected.

(Tech 2 Data parameter “Fuel” displaying LPG).

2. Is the LPG lamp illuminated?

Go to Step 8. Refer 4.6 LPG LAMP

DOES NOT OPERATE

in this Section.

STEP ACTION YES NO

8. 1. Select Petrol via the fuel mode switch.

2. Will the engine crank and start immediately the

ignition key is turned from off to start (no delay)?

Go to Step 9. Refer ON-BOARD

DIAGNOSTIC SYSTEM

CHECK, Section 6C1 in

this Service Information.

9. 1. Select LPG via the fuel mode switch.

2. W ill the engine crank immediately the key is turned

from off to start (no delay)?

Go to Step 10. Refer 4.7 ENGINE

DOES NOT CRANK in

this Section.

10. 1. Does engine start and run on LPG? Go to Step 11. Refer 4.8 ENGINE

CRANKS DOES NOT

START ON LPG in this

Section.

11. 1. Does engine backfire when operated on LPG? Refer Diagnostic Chart 4.9

ENGINE BACKFIRES ON

LPG in this Section.

Go to Step 12.

12. 1. Does engine lack power, sluggish or have poor

performance when operating on LPG?

Refer Diagnostic Chart 4.10

POOR PERFORMANCE,

SLUGGISH OR POOR FUEL

CONSUMPTION WHEN

OPERATING ON LPG in this

Section.

Go to step 13

13. 1. Does fuel gauge operate correctly? LPG Diagnostic Check

completed. Refer 4.12 FUEL

GAUGE DOES NOT

OPERATE in this

Section.

4.4 DOES NOT OPERATE ON LPG

Figure 8A2-58

TEST DESCRIPTION

The numbers below refer to step numbers in the following diagnostic chart.

1. The LPG VEHICLE PRELIMINARY DIAGNOSIS CHECK must be the first step when diagnosing any LPG

system problem.

2. The PCM will not operate in the LPG mode if the PCM has not been programmed to operate on LPG. Refer to

the latest technical publications for the correct PROM application.

3. When the ignition is turned on battery voltage is applied to terminal F16 of the PCM. This enables the PCM to

operate in either the Petrol or LPG mode. If battery voltage is not applied to PCM terminal F16 the PCM will only

operate in the Petrol mode.

4. This test confirms that the PCM connector terminal retention is not causing the problem. The terminal retention

should always be checked before a PCM is replaced.

STEP ACTION YES NO

1. 1. Has an LPG VEHICLE PRELIMINARY DIAGNOSIS

CHECK been performed. Go to step 2 Perform an LPG

VEHICLE PRELIMINARY

DIAGNOSIS CHECK.

2. 1. Has the PCM been programmed for LPG operation?

Go to step 3. Perform SPS to program

the PCM for LPG

operation. Refer SPS,

Section 0C Tech 2 in this

Service Information.

3. 1. Ignition on.

2. Measure the voltage at PCM terminal F16 connector

YB199 circuit 39 pink wire.

3. Is battery voltage present?

Go to step 4. Repair open in circuit 39

between fuse F14 and

PCM terminal F16.

Verify repair.

4. 1. Check PCM connector terminal retention.

If retention OK replace PCM.

2. Is terminal retention OK?

Replace PCM.

Verify repair. Repair terminals.

Verify repair.

4.5 FUEL MODE SWITCH DOES NOT OPERATE

Figure 8A2-59

TEST DESCRIPTION

The numbers below refer to step numbers in the following diagnostic chart.

1. The LPG VEHICLE PRELIMINARY DIAGNOSIS CHECK must be the first step when diagnosing any LPG

system problem.

2. Checks for battery voltage when the Fuel Mode switch is activated.

3. Tests operation of fuel mode switch.

4. Checks for voltage at the fuel mode switch. If voltage is not present, circuit 39 is open between the fuel mode

switch and fuse F14. If voltage is present there is an open circuit between the fuel mode switch and PCM

terminal F4.

5. This test check for an open in the fuel mode switch circuit 936.

6. This test confirms that the PCM connector terminal retention is not causing the problem. The terminal retention

should always be checked before a PCM is replaced.

STEP ACTION YES NO

1. 1. Has an LPG VEHICLE PRELIMINARY DIAGNOSIS

CHECK been performed. Go to step 2 Perform an LPG

VEHICLE PRELIMINARY

DIAGNOSIS CHECK.

2. 1. Ignition On

2. Measure the voltage at PCM terminal F4.

3. Is battery voltage present when the fuel mode

switch is depressed?

Go to step 6. Go to step 3.

3. 1. Test fuel mode switch.

Refer 2.22 FUEL MODE SWITCH TEST in Section

8A2 in the VT Series I LPG System Service

Information.

2. Is the fuel mode switch OK.

Go to step 4. Replace fuel mode

switch.

Verify repair.

4. 1. Ignition on.

2. Measure the voltage at the fuel mode switch

connector YB68 circuit 39 (Pink wire).

3. Is battery voltage present?

Go to step 5. Repair open in circuit 39

between fuse F14 and

fuel mode switch.

Verify repair.

5. 1. Check for open in circuit 936 (Blue/Orange wire)

between fuel mode switch and PCM terminal F4.

2. Is circuit open?

Repair open in circuit 936.

Verify repair. Go to step 6.

6. 1. Check PCM connector terminal retention.

2. Is terminal retention OK. Replace PCM.

Verify repair. Repair terminals.

Verify repair.

4.6 LPG LAMP DOES NOT OPERATE

TEST DESCRIPTION

The numbers below refer to step numbers in the following diagnostic chart.

1. The LPG VEHICLE PRELIMINARY DIAGNOSIS CHECK must be the first step when diagnosing any LPG

system problem.

2. If the LPG Lamp is not enabled, it will not be illuminated when operating in the LPG mode. Refer to

Section 12C INSTRUMENTS, WIPERS / WASHERS AND HORNS in the VT Series II Service Information for

instrument programming options.

3. Tests the operation of the LPG lamp using Tech 2 to command the lamp on and off.

4. This step determines if the bulb or socket is defective.

5. T his st ep chec k s if the PCM is c om m anding the instr um ent to turn on the LPG lam p. If the PCM is c om m anding

the instrument to turn on the LPG lamp and it does not the instrument is defective. If the PCM is not

commanding the instrument to turn on the LPG lamp then the PCM if defective.

STEP ACTION YES NO

1. 1. Has an LPG VEHICLE PRELIMINARY DIAGNOSIS

CHECK been performed. Go to step 2 Perform an LPG

VEHICLE PRELIMINARY

DIAGNOSIS CHECK.

2. 1. Is the LPG Lamp Enabled?

Go to Step 3. Enable LPG Lamp, refer

to Section 12C

INSTRUMENTS, WIPERS

/ WASHERS AND

HORNS in the VT Series

II Service Information.

3. 1. Install Tech 2 to DLC.

2. Select Body / Instruments / Miscellaneous Tests /

Lamps / LPG In Use Lamp.

3. Command LPG In Use Lamp On and Off.

4. Does the LPG Lamp turn On and Off when

commanded?

Go to Step 5. Go to step 4.

4. 1. Remove Instrument Cluster, refer Section 12C

INSTRUMENTS, WIPERS / WASHERS AND

HORNS in the VT Series II Service Information.

2. Remove LPG lamp bulb and socket from instrument

cluster and check bulb and socket condition.

3. Is bulb and socket OK?

Go to Step 5. Replace bulb and/or

socket.

Verify Repair.

5. 1. W ith Tech 2 still connected select Engine / V6 / F0:

Normal Mode.

2. Scroll to Fuel Type.

3. Does the Tech 2 display LPG, when LPG is selected

via the fuel mode switch.

Replace instrument

cluster, refer to Section

12C INSTRUMENTS,

WIPERS / WASHERS

AND HORNS in the VT

Series II Service

Information.

Replace PCM refer to

Section 6C1-3 SERVICE

OPERATIONS - V6

ENGINE in this Service

Information.

4.7 ENGINE DOE S NOT CRANK

TEST DESCRIPTION

The numbers below refer to step numbers in the following diagnostic chart.

1. The LPG VEHICLE PRELIMINARY DIAGNOSIS CHECK must be the first step when diagnosing any LPG

system problem.

2. The Theft Deterrent System must be disarmed before the engine will crank. If the Theft Deterrent System cannot

be disarmed, refer to Theft Deterrent Diagnostics in Section 12J1 in the VX Series Service Information for

vehicles fitted with Low Series BCM’s or Section 12J2 in the VT Series I Service Information for vehicles fitted

with High Series BCM’s in this Service Information.

3. When PETROL is selected the engine should c rank im mediately the ignition switch is turned from off to start. If

the engine does not crank im m ediately, then ref er to ON-BOARD DIAGNOST IC SYSTEM CHECK , Sec tion 6C1

in this Service Information.

4. When LPG is s elected The engine should c rank im mediately the ignition switch is turned fr om off to start. If the

engine cranks immediately system is operating correctly.

5. When LPG is s elected the PCM will prevent the engine from c rank ing if the PCM deter m ines the throttle is open

more than 7%. This tests uses Tech 2 to monitor the Throttle Position sensor operation.

STEP ACTION YES NO

1. 1. Has an LPG VEHICLE PRELIMINARY DIAGNOSIS

CHECK been performed. Go to step 2 Perform an LPG

VEHICLE PRELIMINARY

DIAGNOSIS CHECK.

2. 1. Ignition On.

2. Is theft deterrent system disarmed?

(Theft Deterrent LED not flashing).

Go to Step 3. Refer Section 12J1 Low

Series BCM or 12J2 High

Series BCM in this

Service Information.

3. 1. Ignition on, Select Petrol via the fuel mode switch.

2. Turn ignition switch from “OFF” to “START” for a

maximum of five seconds or until engine starts to

crank.

3. Does engine crank immediately (less than one

second)?

Go to Step 4. Refer ON-BOARD

DIAGNOSTIC SYSTEM

CHECK, Section 6C1 in

this Service Information.

4. 1. Ignition on select LPG via the fuel mode switch.

2. Turn ignition switch from “OFF” to “START” for a

maximum of five seconds or until engine starts to

crank.

3. Does engine crank immediately (less than one

second)?

System operating

correctly.

Check for intermittent

connections.

Go to Step 5.

5. 1. Turn ignition off.

2. Install Tech 2 to DLC.

3. Turn ignition ON.

4. Push power button on Tech 2.

5. Select ENGINE / V6 / Data List / All Data.

6. Scroll to Throttle Position Sensor.

7. Is Throttle Position sensor displaying 0%?

Refer ON-BOARD

DIAGNOSTIC SYSTEM

CHECK, Section 6C1 in

this Service Information.

Refer Chart A-6.2 TP

SENSOR OUTPUT

CHECK, Section 6C1-2A

in this Service

Information.

4.8 ENGINE CRANKS BUT WILL NOT START ON LPG (1)

Figure 8A2-60

TEST DESCRIPTION

The numbers below refer to step numbers in the following diagnostic chart.

1. The LPG VEHICLE PRELIMINARY DIAGNOSIS CHECK must be the first step when diagnosing any LPG

system problem.

2. These initial checks are designed to verify that the engine is capable of operating on LPG.

3. Voltage is supplied to the LPG lock-off from the smart unit when the ignition is first turned on and when the

engine is crank ing or running. If voltage is not present at these tim es the loc k-of f will not be energised and LPG

will not flow to the converter.

4. This test confirms correct converter operation. Incorrect converter pressures can cause the engine not to start.

5. This test determines if the ADP is causing the no start condition.

6. Vacuum leaks or blockages can cause a variety of system operating problems all hoses and vacuum lines

should be checked.

7. This tests confirms correct mixer operation.

8. This tests confirms correct ADP set up.

STEP ACTION YES NO

1. 1. Has an LPG VEHICLE PRELIMINARY DIAGNOSIS

CHECK been performed. Go to step 2. Perform an LPG

VEHICLE PRELIMINARY

DIAGNOSIS CHECK.

2. INITIAL CHECKS:

1. Has LPG been selected via the fuel mode switch?

2. Has the PCM been programmed to operate on LPG?

3. Is the manual service valve open?

4. Is there any LPG present in the LPG cylinder, check

contents gauge?

If yes to all, go to Step 3. Repair any faults.

Recheck starting on LPG.

3. 1. Measure the voltage at LPG lock-off connector YE2

circuit 965 (Blue/Yellow wire).

2. Is voltage above nine volts for three seconds when

the ignition is first turned on or while the engine is

cranking?

Go to Step 4. Go to Diagnostic Chart

ENGINE CRANKS BUT

WILL NOT START ON

LPG (2) on the following

page in this Section.

4. 1. Test for presence of LPG in system by checking

converter pressures.

(Refer 3.1 CONVERTER in this Section).

2. Are converter pressures OK?

Go to Step 5. Go to Diagnostic Chart

ENGINE CRANKS BUT

WILL NOT START ON

LPG (3) in this Section.

5. 1. Ignition on, select Petrol via the fuel mode switch.

2. Start engine and bring to 2000 RPM.

3. Select the LPG mode via the fuel mode switch.

4. Does the engine continue to run?

Setup LPG System. Refer

3.5 LPG SETUP

PROCEDURE in this

Section

Recheck starting on LPG.

Go to Step 6.

6. 1. Check for vacuum leaks or incorrect routing in

vacuum or vapour feed lines between mixer and

converter, or a blocked balance line, FCV or

Regulator Check Valve.

2. Are there any leaks, incorrect routing or blockages?

Repair vacuum leaks or

blockages.

Recheck starting on LPG.

Go to Step 7.

7. 1. Test mixer operation

(refer 3.4 MIXER in this Section).

2. Is mixer operating correctly?

Go to Step 8. Check and repair any air

leaks between mixer and

throttle body, if no leaks

overhaul mixer. Refer

2.18 MIXER in the VT

Series I Service

Information - LPG

System.

Recheck starting on LPG.

8. 1. Perform an LPG Setup (refer 3.5 LPG SETUP

PROCEDURE in this Section) and recheck starting

on LPG.

2. Does engine start on LPG?

System OK. Go to Diagnostic Chart

ENGINE CRANKS BUT

WILL NOT START ON

LPG (2) on the following

page in this Section.

ENGINE CRANKS BUT WILL NOT START ON LPG (2)

Figure 8A2-61

TEST DESCRIPTION

1. This test checks that the smart unit is supplying voltage to circuit 965.

2. This test checks if circuit 965 is shorted to earth.

NOTE: the sm art unit has a current protection device on this circuit, if circuit 965 is shorted to earth the smart unit

will shutdown. The ignition must be cycled from on to off to reset the smart unit.

3. T his test chec ks the continuity of the sm art unit earth circuit if the smart unit does not have a good earth then it

will not operate.

4. This test checks that voltage is being applied to the smart unit from Fuse F14.

5. Ignition voltage should be present at PCM terminal F16 circuit 39 whenever the ignition is on.

6. When operating in the LPG mode, the PCM puls es the 12 volt pull up in the smart unit to earth via circ uit 937 at

a 50% duty cycle. Therefore the voltage at PCM terminal A3 should be approximately five volts when the ignition

is first turned on or when the engine is cranking.

7. This test checks the continuity of circuit 937(White/Green wire).

8. This test checks if circuit 937(White/Green wire) is shorted to earth.

STEP ACTION YES NO

1. 1. Ignition On, LPG selected.

2. Measure the voltage at smart unit connector

YR50/YR51 circuit 965 (Blue/Yellow wire).

3. Is voltage above nine volts for three seconds when

the ignition is first turned on or while the engine is

being cranked?

Repair open in LPG lock-

off circuit 965 between

smart unit and lock-off.

Recheck starting on LPG.

Go to Step 2.

2. 1. Check for short to earth in LPG lock-off circuit 965

between smart unit and lock-off.

2. Is circuit 965 shorted to earth?

Repair short to earth in

LPG lock-off circuit 965

between smart unit and

lock-off.

Recheck starting on LPG.

Go to step 3.

3. 1. Check continuity of smart unit earth circuit 750

(Black/Red wire) between smart unit connector

YR50/YR51 and a known good earth.

2. Is there continuity?

Go to step 4. Repair open in circuit 750

(Black/Red wire).

Recheck starting on LPG.

4. 1. Ignition On.

2. Measure the voltage at smart unit connector

YR50/YR51 circuit 39 (Pink wire).

3. Is battery voltage present?

Go to Step 5. Repair open in circuit 39

(Pink wire) between the

Fuse F14 and smart unit.

5. 1. Ignition On.

2. Measure the voltage at PCM terminal F16 circuit 39

(Pink wire).

3. Is battery voltage present?

Go to step 6. Repair open in circuit 39

(Pink wire) between the

Fuse F14 and PCM

terminal F16.

Recheck starting on LPG.

6. 1. With LPG selected via the fuel mode switch.

2. Disconnect smart unit connector YR50/YR51.

3. Measure the voltage at smart unit connector

YR50/YR51 circuit 937 PCM side (White/Green

wire).

4. Turn the ignition from Off to On, is voltage

approximately five volts for three seconds when the

ignition is first turned on or when the engine is

cranking?

Check smart unit

connector terminal

retention if OK, replace

Smart Unit.

Verify repair.

Go to step 7.

7. 1. With LPG selected via the fuel mode switch.

2. Measure the voltage at PCM terminal A3 circuit 937

(White/Green wire).

3. Turn the ignition from Off to On, is voltage

approximately five volts for three seconds when the

ignition is first turned from Off to On or when the

engine is cranking?

Go to step 8. Check PCM connector

terminal retention, if OK,

Replace PCM.

Recheck starting on LPG.

8. 1. Check continuity of circuit 937 (White/Green wire)

between smart unit connector YR50/YR51 and PCM

connector YB197 terminal A3.

2. Is there continuity?

Go to step 9. Repair open in circuit 937

(White/Green wire).

Verify repair.

9. 1. Check for a short to earth in circuit 937

(White/Green wire) between smart unit connector

YR50/YR51 and PCM connector YB197 terminal A3.

2. Is there a short to earth?

Repair short to earth in

circuit 937

(White/Green wire).

Verify repair.

Check PCM connector

terminal retention, if OK,

Replace PCM.

Recheck starting on LPG.

ENGINE CRANKS BUT WILL NOT START ON LPG (3)

TEST DESCRIPTION

1. Low primary converter pressure can be caused by low supply pressure or a faulty converter.

2. If the primary converter pressure is too high the converter will have to be overhauled.

3. If the primary converter pressure is within specification but the secondary converter pressure is out of

specification the converter will have to be overhauled.

4. This test checks if the solenoid valve is restricting the flow of LPG.

5. This tests check the flow of LPG from the LPG cylinder to the LPG lock-off.

6. This tests determines if the LPG lock-off or the converter is causing the problem.

7. T his tes ts check if the service line is block ed. If the ser vice line is not blocked then the m anual service valve or

the LPG cylinder pick up must be blocked.

STEP ACTION YES NO

1. 1. Is primary converter pressure below specification? Go to Step 4. Got to Step 2.

2. 1. Is primary converter pressure above specification? Repair converter, refer 3.1

CONVERTER in this

Section. Recheck starting

on LPG.

Go to Step 3.

3. 1. If primary converter pressure is within specification,

is the secondary converter pressure out of

specification?

Repair converter, refer

2.15 CONVERTER in the

VT Series I Service

Information - LPG

System. Recheck starting

on LPG.

Go to step 4.

4. 1. Ignition off.

2. Close manual service valve.

3. Remove the solenoid valve from the manual service

valve assembly and reinstall solenoid sleeve, refer

2.8 SMART UNIT AND SOLENOID VALVE

in the VT Series I Service Information - LPG System.

4. Does engine start and run on LPG?

Replace Smart unit and

solenoid valve.

Recheck starting on LPG.

Go to Step 5.

5. 1. Ignition off.

2. Close manual service valve.

3. With the solenoid valve still removed from the

manual service valve assembly.

4. Disconnect the front service line at the LPG lock-off.

5. In accordance with AS-1425, have a second

technician slowly open the manual service valve so

that the excess flow valve doesn’t shut LPG flow off

(if a click is herd at the manual service valve, the

excess flow valve has closed).

6. Does LPG flow from the front service line?

Go to Step 6. Go to Step 7.

6. 1. Test LPG lock-off (refer 2.14 LPG LOCK-OFF in the

VT Series I Service Information - LPG System).

2. Is LPG lock-off OK?

Repair converter, refer

2.14 CONVERTER in the

VT Series I Service

Information - LPG

System. Recheck starting

on LPG.

Repair LPG lock-off, refer

2.14 LPG LOCK-OFF in

the VT Series I Service

Information - LPG

System. Recheck starting

on LPG.

7. 1. Disconnect rear service line at manual service valve.

2. With front service line still disconnected, blow air

through service line to check for blockages

3. Does air flow through service line?

Check for manual service

valve or LPG cylinder fuel

pick-up blockage or fault.

Repair or replace blocked

or damaged components.

Recheck starting on LPG.

Check for damaged or

blocked service lines.

Repair or replace blocked

or damaged components.

Recheck starting on LPG.

4.9 ENGINE BACKFIRES ON LPG

TEST DESCRIPTION

The numbers below refer to step numbers in the following diagnostic chart.

NOTE: Whenever a engine backfire has occurred the complete intake system including the mixer should be

checked for damage.

1. The LPG VEHICLE PRELIMINARY DIAGNOSIS CHECK must be the first step when diagnosing any LPG

system problem.

2. An ON BOARD DIAGNOSTIC SYSTEM CHECK should be performed to confirm that a problem with the

Powertrain Management system is not causing the engine to backfire when operating on LPG?

3-7 An ignition system that is not operating at it’s full potential can cause an engine to backfire when operating on

LPG. Ignition leads that operate quite well when operating on petrol, can cause problems when operating on

LPG. Therefore, all ignition system components must be at here optimum when operating on LPG.

8. Vacuum leaks or blocked vacuum lines can cause incorrect system operation, causing engine backfire.

9. Incorrect mixer operation can cause incorrect air/fuel ratios. Incorrect air/fuel ratios can cause engine backfire.

10. Incorrect ADP set-up can cause incorrect system operation, causing engine backfire.

11. Incorrect converter operation can cause incorrect air/fuel ratios. Incorrect air/fuel ratios can cause engine

backfire.

12. This test confirm correct Regulator Check Valve (RCV) operation, incorrect RCV operation can cause slow

converter response causing engine backfire.

13. Engine mechanical condition can cause engine operating problems that do not effect the engine when operating

on petrol. The engine must be in optimum operating condition to prevent the engine backfiring when operating

on LPG.

STEP ACTION YES NO

1. 1. Has an LPG VEHICLE PRELIMINARY DIAGNOSIS

CHECK been performed. Go to step 2 Perform an LPG VEHICLE

PRELIMINARY DIAGNOSIS

CHECK.

2. 1. Has an ON BOARD DIAGNOSTIC SYSTEM CHECK

been performed?

Refer ON-BOARD DIAGNOSTIC SYSTEM CHECK,

Section 6C1 in this Service Information.

Go to Step 3. Perform ON-BOARD

DIAGNOSTIC SYSTEM

CHECK. Refer Section 6C1 in

this Service Information.

Recheck for engine backfire.

3. 1. Check spark plug leads for tracking or cracks in

insulation and resistance (refer Section 6D1 in this

Service Information).

2. Are the spark plugs leads OK?

Go to Step 4. Replace spark plug leads.

Recheck for engine backfire.

4. 1. Remove and inspect spark plugs for fouling.

2. Are the spark plugs OK? Go to Step 5. Replace spark plugs. Recheck

for engine backfire.

5. 1. Re-gap spark plugs to minimum specification.

2. Have spark plugs been re-gaped to minimum

specification?

Go to Step 6. Re-gap spark plugs to

minimum specification

Recheck for engine backfire.

6. 1. Check coil resistance (refer Section 6D1 in this

Service Information).

2. Is the ignition coil resistance within specification?

Go to Step 7. Replace faulty ignition coil.

Recheck for engine backfire.

7. 1. Check PCM, DIS and Crank Angle sensor wiring

harness terminal retention.

2. Is terminal retention OK?

Go to Step 8. Resize terminals. Recheck for

engine backfire.

8. 1. Check for vacuum leaks in vacuum or vapour feed

lines between mixer and converter, or a blocked

balance line, FCV or Regulator Check Valve.

2. Are there any leaks or blockages?

Repair vacuum

leaks or blockages.

Recheck for engine

backfire.

Go to Step 9.

9. 1. Test mixer operation (refer 3.4 MIXER in this

Section).

2. Is mixer operating correctly?

Go to Step 10. Overhaul mixer. Refer 2.18

MIXER in the VT Series I

Service Information - LPG

System.

Recheck for engine backfire.

10. 1. Is the LPG Setup correct?

(refer 3.5 LPG SETUP PROCEDURE in this

Section).

Go to Step 11. Carry out LPG Setup

Procedure.

Recheck for engine backfire.

11. 1. Test converter pressures. (Refer 3.1 CONVERTER

in this section).

2. Are converter pressures OK?

Go to Step 12. Overhaul converter.

(Refer 2.15 CONVERTER in

the VT Series I Service

Information - LPG System).

12. 1. Test Regulator Check Valve operation (refer 3.2

REGULATOR CHECK VALVE in this Sec t ion).

2. Is Regulator Check Valve operating correctly?

Go to Step 13. Replace Regulator Check

Valve (refer 3.2 REGULATOR

CHECK VALVE in this Section)

Recheck for engine backfire.

13. 1. Check engine mechanical condition by checking

compression, valve timing, intake and exhaust

valves and manifolds for casting flash.

2. Is the engine mechanical condition OK?

Check for incorrectly

routed harnesses,

ignition leads

or non genuine

accessories.

Repair any faults. Recheck for

engine backfire.

4.10 POOR PERFORMANCE, FLAT SPOTTING, SLUGGISH OR POOR

FUEL CONSUMPTION WHEN OPERATING ON LPG

Because of the nature of LPG, a minimal loss of power may be experienced under heavy acceleration, this

is expected and quite normal.

TEST DESCRIPTION

The numbers below refer to step numbers in the following diagnostic chart.

1. The LPG VEHICLE PRELIMINARY DIAGNOSIS CHECK must be the first step when diagnosing any LPG

system problem.

2. An ON BOARD DIAGNOSTIC SYSTEM CHECK should be performed to confirm that a problem with the

Powertrain Management system is not causing the engine to backfire when operating on LPG?

3. These symptoms checks this the most common causes of engine drivability problems.

4. Incorrect ADP operation can cause incorrect air/fuel ratios.

5. Incorrectly tensioned air valve to diaphragm attaching screws can cause incorrect mixer operation.

6. Correct mixer operation is required so that the correct air/fuel ratio is achieved.

7. A regulator check valve that is blocked or opening at the wrong vacuum can cause incorrect converter operation.

8. T he converter is one of the key components in the control of the delivery of LPG. Incorrect converter operation

can cause rich or lean mixtures.

STEP ACTION YES NO

1. 1. Has an LPG VEHICLE PRELIMINARY DIAGNOSIS

CHECK been performed. Go to step 2 Perform an LPG

VEHICLE PRELIMINARY

DIAGNOSIS CHECK.

2. 1. Has an ON BOARD DIAGNOSTIC SYSTEM CHECK

been performed?

Refer ON-BOARD DIAGNOSTIC SYSTEM CHECK,

Section 6C1 in this Service Information.

Go to Step 3. Perform ON-BOARD

DIAGNOSTIC SYSTEM

CHECK. Refer Section

6C1 in of this Service

Information.

Recheck performance.

3. 1. Carry out SYMPTOMS CHECK (refer Section, 6C1-

2B in this Service Information).

2. Are all checks OK?

Go to Step 4. Repair any faults.

Recheck performance.

4. 1. Has an LPG Setup Procedure been performed?

(refer 3.5 LPG SET-UP PROCEDURE in this

Section).

Go to Step 5. Carry out the LPG Setup

Procedure.

Recheck performance.

5. 1. Check air valve to diaphragm attaching screws for

correct torque.

(refer 2.18 MIXER in the VT Series I Service

Information - LPG System).

2. Are screws tightened to the correct torque?

Go to Step 6. Tension Screws to the

correct torque

specification. Refer 2.18

MIXER in the VT Series I

Service Information - LPG

System. Recheck

performance.

6. 1. Test mixer operation (refer 3.4 MIXER in this

Section).

2. Is mixer operating correctly?

Go to Step 7. Overhaul mixer. Refer

2.18 MIXER in the VT

Series I Service

Information - LPG

System.

Recheck performance.

7. 1. Test Regulator Check Valve operation (refer 3.2

REGULATOR CHECK VALVE in this Sec t ion).

2. Is Regulator Check Valve operating correctly?

Go to Step 8. Replace Regulator Check

Valve.

Recheck performance.

8. 1. Test converter operation (refer 3.1 CONVERTER in

this Section).

2. Is converter operating correctly?

Repair converter, refer

2.16 CONVERTER in the

VT Series I Service

Information - LPG

System. Recheck

performance.

4.11 FUEL CONTROL VALVE DOES NOT OPERATE

Figure 8A2-62

TEST DESCRIPTION

The numbers below refer to step numbers in the following diagnostic chart.

1. The LPG VEHICLE PRELIMINARY DIAGNOSIS CHECK must be the first step when diagnosing any LPG

system problem.

2. This test confirm if the FCV is operating correctly.

3. This test confirms the continuity of the FCV circuit 39 and 1062.

4. This test confirms that the PCM is pulsing the FCV circuit to earth.

5. This test confirms that voltage is being applied to the FCV from fuse F14.

6. This test confirms that circuit 1062 is not open or shorted to battery voltage.

7. This test confirms that circuit 1062 is not shorted to earth.

8. This test checks the operation of the FCV.

9. This test confirms the retention of the PCM terminals. If the terminal retention is OK, the PCM should be

replaced.

STEP ACTION YES NO

1. 1. Has an LPG VEHICLE PRELIMINARY DIAGNOSIS

CHECK been performed? Go to step 2. Perform an LPG

VEHICLE PRELIMINARY

DIAGNOSIS CHECK.

2. 1. Perform a Fuel Control Valve Test (refer 3.3 FUEL

CONTROL VALVE TEST in this Section).

2. Is the Fuel Control Valve Operating correctly

Fuel Control Valve

operation is intermittent.

Check all FCV circuit

terminal retention.

Go to Step 3.

3. 1. Ignition off, disconnect PCM Connector YB199.

2. Ignition on.

3. Measure the voltage at the FCV circuit 1062

(Black/Blue wire) between the PCM connector

YB199 and earth.

4. Is battery voltage present?

Reconnect PCM

Connector YB199

Go to Step 5.

Reconnect PCM

Connector YB199

Go to Step 4.

4. 1. Ignition On, LPG selected.

2. Measure the voltage PCM terminal E16 connector

YB199 circuit 1062 (Black/Blue wire) and earth.

3. Turn the ignition from off to on, is at least nine volts

present for three seconds when the ignition is first

turned on or when the engine is cranking?

Go to step 8. Go to Step 5.

5. 1. Ignition off.

2. Disconnect FCV connector YE35.

3. Ignition on.

4. Measure the Voltage at the FCV connector YE35

circuit 39 (Pink wire) and earth.

5. Is battery voltage present?

Go to step 6. Repair open in circuit 39

(Pink/Black wire) between

fuse F14 and connector

YE35.

6. 1. Check for open or short to voltage in circuit 1062

(Black/Blue wire) between FCV connector YE35 and

the PCM.

2. Is circuit open or shorted to voltage?

Repair open or short to

voltage circuit 1062

(Black/Blue wire).

Verify repair.

Go to Step 7.

7. 1. Check for a short to earth in circuit 1062 (Black/Blue

wire).

2. Is circuit 1062 (Black/Blue wire) shorted to earth?

Repair short to earth in

circuit 1062

(Black/Blue wire).

Verify repair.

Go to step 8.

8. 1. Test operation of FCV, (refer 3.3 FUEL CONTROL

VALVE in this Section ).

2. Is FCV operating correctly?

Fuel Control Valve

operation is intermittent.

Check all FCV circuit

terminal retention.

Replace FCV.

Verify repair.

9. 1. Check PCM connector terminal retention.

2. Is PCM terminal retention OK. Replace PCM.

Recheck starting on LPG. Repair PCM terminals.

4.12 FUEL GAUGE DOES NOT OPERATE

Figure 8A2-63

TEST DESCRIPTION

CAUTION: All safety precautions listed in 2.12 CYLINDER FUEL GAUGE ASSEMBLY in the VT Series I

Service Info rmation, VT Sedan with Production LPG or VT Sed an wit h Accessory LPG an d VT W agon must

be adhered to when carrying out the procedur es listed in this diagnostic chart.

The numbers below refer to step numbers in the following diagnostic chart.

1. The LPG VEHICLE PRELIMINARY DIAGNOSIS CHECK must be the first step when diagnosing any LPG

system problem.

2. In this test Tech 2 is used to test the operation of the instrument fuel gauge.

3. This test confirms the operation of the fuel gauge when the vehicle is operating on petrol.

4. This test confirms correct operation of the cy linder fuel gauge assembly.

5. If the Tech 2 instrument LPG sender signal is displaying 5 volts the LPG sender circuit is open circuited.

6. If the Tech 2 instrument LPG sender signal is displaying 0 volts the LPG sender circuit is short to earth.

7. In this test step circuit 1030 is checked for a short to earth.

8. In the test step earth circuit 155 is checked for continuity.

9. This test step checks the continuity of circuit 1030 between the cylinder fuel gauge and the instrument assembly.

10. In this test step the cylinder fuel gauge assembly is removed from the LPG cylinder and checked for correct

operation.

STEP ACTION YES NO

1. 1. Has an LPG VEHICLE PRELIMINARY DIAGNOSIS

CHECK been performed. Go to step 2 Perform an LPG

VEHICLE PRELIMINARY

DIAGNOSIS CHECK.

2. 1. Install Tech 2 to DLC.

2. Select Body / Instruments / F4: Miscellaneous Tests

/ F7: Control Tests / F3: Fuel Gauge Level

3. Run Fuel Gauge Level test.

4. Does fuel gauge operate correctly?

Go to Step 3. Replace instrument

cluster, refer to Section

12C INSTRUMENTS,

WIPERS / WASHERS

AND HORNS in VT Series

II Service Information.

3. 1. Does fuel gauge operate when petrol is selected via

the fuel mode switch.

Go to step 4. Refer 3.13 FUEL GAUGE

DOES NOT OPERATE

WHEN PETROL

SELECTED in this

Section.

4. 1. Test operation of cylinder fuel gauge.

(refer 2.12 CYLINDER FUEL GAUGE ASSEMBLY in

the VT Series I LPG System Service Information).

2. Is cylinder fuel gauge operating correctly?

Go to step 5. Replace cylinder fuel

gauge. (refer 2.12

CYLINDER FUEL

GAUGE ASSEMBLY in

VT Series I Service

Information - LPG

System).

5. 1. Install Tech 2 to DLC select Body/ Instruments / F2:

Data Display / F0: Instrument.

2. Scroll to LPG Sender Signal.

3. Is the LPG Sender Signal 5 Volts.

Go to step 7. Go to step 6.

6. 1. In test step 5 was the LPG Sender Signal 0 Volts?

Go to step 7. Go to step 8.

7. 1. Check for short to earth in circuit 1030 (Yellow wire).

2. Is circuit 1030 (Yellow wire) shorted to earth?

Repair short to earth in

circuit 1030 (Yellow wire).

Verify Repair.

Go to step 9.

8. 1. Check continuity of circuit earth circuit 155, (Black

wire) between connector YR50 and a known good

earth.

2. Is there continuity?

Go to step 9. Repair open in earth

circuit 155,

(Black/Yellow wire).

Verify Repair.

9. 1. Check continuity of circuit 1030, (Yellow wire)

between connector YR50 and instrument assembly

connector YB66.

2. Is there continuity?

Go to step 10. Repair open in circuit

1030 (Yellow wire).

Verify Repair.

10. 1. Remove cylinder fuel gauge assembly.

(refer 2.12 CYLINDER FUEL GAUGE ASSEMBLY in

Section 2 of the VT Series I Service Information -

LPG System).

1. Check operation of cylinder fuel gauge assembly.

(Check for binding, jammed & smooth operation).

2. Does cylinder fuel gauge assembly operate

correctly?

Check all connector

terminal retention.

Monitor Tech 2 Instrument

Data List while

manipulating wiring

harness to check for an

intermittent connection.

Replace cylinder fuel

gauge assembly. (refer

2.12 CYLINDER FUEL

GAUGE ASSEMBLY in

VT Series I Service

Information - LPG

System).

Verify repair.

4.13 FUEL GAUGE DOES NOT OPERATE WHEN PETROL SELECTED

Figure 8A2-64

TEST DESCRIPTION

The numbers below refer to step numbers in the following diagnostic chart.

1. The LPG VEHICLE PRELIMINARY DIAGNOSIS CHECK must be the first step when diagnosing any LPG

system problem.

2. In this test Tech 2 is used to check the signal from the fuel gauge sender.

3. In this tes t T ech 2 is us ed to check circuit 30 (T an wire), if the f uel gauge sender unit s ignal is not 0 volts circuit

30 is open.

4. In this tes t T ech 2 is us ed to check circuit 30 (T an wire), if the f uel gauge sender unit s ignal is not 5 volts circuit

30 is shorted to earth.

5. This test confirms correct operation of the fuel gauge sender unit.

6. This test confirms correct fuel gauge sender unit operation.

STEP ACTION YES NO

1. 1. Has an LPG VEHICLE PRELIMINARY DIAGNOSIS

CHECK been performed. Go to step 2 Perform an LPG

VEHICLE PRELIMINARY

DIAGNOSIS CHECK.

2. 1. Install Tech 2 to DLC select Body/ Instruments / F2:

Data Display / F0: Instrument.

2. Scroll to Fuel Gauge Sender Signal.

3. Is the Fuel Gauge Sensor Signal 5 Volts.

Go to step 3. Go to step 4.

3. 1. With Tech 2 still connected.

2. Disconnect fuel gauge sender unit connector YR44.

3. Jumper circuit 30 (Tan wire) to a known good earth.

4. Is the Fuel Gauge Sensor Signal 0 Volts.

Go to step 6. Repair open in circuit 30

(Tan wire).

Verify repair.

4. 1. With Tech 2 still connected.

2. Disconnect fuel gauge sender unit connector YR44.

3. Is the Fuel Gauge Sensor Signal 5 Volts.

Go to step 5. Repair short to earth in

circuit 30 (Tan wire).

Verify repair.

5. 1. Disconnect connector YR44.

2. Check continuity of fuel gauge sender unit earth

circuit 155 (Black/Yellow wire) between connector

YR44 and a known good earth.

3. Is there continuity?

Go to step 6. Repair open in earth

circuit 156,

(Black/Blue wire).

Verify Repair.

6. 1. Test operation of fuel gauge sender unit.

(refer 2.3 SENDER UNIT in Section 12C of the VT

Series I Service Information).

2. Is fuel gauge sender unit operating correctly.

Check all connector

terminal retention.

Monitor Tech 2 Instrument

Data List while

manipulating wiring

harness to check for an

intermittent connection.

Replace fuel gauge

sender unit.

(refer 2.2 & 2.3 FUEL

SENDER ASSEMBLY in

Section 8A Fuel Tank of

the VT Series I Service

Information.

4.14 TECH 2 SCAN TOOL: ENGINE DATA

NOTE: When operating in the LPG mode all of the lef t hand oxygen sensor inf or mation will be fr ozen or invalid, this

is because the PCM only monitors the right hand oxygen sensor when operating on LPG. The values that are frozen

or invalid are shaded in the following table.

TYPI CAL D ATA VALUE S

SCAN POSITION Q UNITS DISP L AYED R IGNITION ON T ENGI NE RUNNING U

ENGINE SPEED RPM 0 RPM ± 100 RPM FROM DESIRE D RP M

(± 50 RPM IN DRIVE )

DESIRED IDLE S PEED RPM 0 RPM PCM IDLE COMMAND (V ARIES WITH

TEMPERATURE)

ENG. COOLANT TEMP (ECT) VOLTS VARIES VARIES

COOLANT TEMPERATURE DEGREES C VARIES VARIES

IAT VOLTS VARIES VARIES

INTAKE AIR TEMPERATURE DEGREES C VARIES VARIES

MAF SENSOR FREQUENCY Hz 0 Hz 2200-2500 Hz

MASS AI R FLOW GRA M /S EC 0 g/s 5 –10 g/s

MASS AI R FLW/CYL Mg/S 0.0 Mg/S 140 to 150 Mg/S

TPS SI GNA L VOLTS 0.36 V 0.36 V

THROTTLE ANGLE 0-100 % 0 % 0 %

RH 02 SENSOR READY YES/NO NO YES

LH 02 SENSOR READY YES/NO NO YES

RH 02 SENSOR Mv 447 Mv 100-1000 Mv AND VARYI NG

LH 02 SENSOR Mv 447 Mv 100-1000 Mv AND VARYI NG

RH ST FUEL TRIM + 100% TO –100% +0% + 0% +10% TO –10%

LH ST FUEL TRIM + 100% TO –100% +0% + 0% +10% TO –10%

LT FUEL TRIM R + 100% to – 100 % + 0 % + 0 % + 10% to – 10%

LT FUEL TRIM L + 100% to – 100 % + 0 % + 0 % + 10% to – 10%

LTFT ENABLE YES / NO NO NO

FUELING MODE OP EN / CLOSED

LOOP OPE N LOOP CLOSED LOOP

LTFT CELL CELL # 0 0

RH O2 STATUS RICH / LEAN LE A N LEAN

LH O2 STATUS RICH / LE A N LEAN LEAN

RH O2 CROSS CNTS COUNTS 0 0

LH O2 CROSS CNTS COUNTS 0 0

STFT DELTA 0 – 100 % 0 % 0 %

LTFT DELTA 0 – 100 % 0 % 0 %

DECEL FUEL CUTOFF NO/YES NO NO

INJ. P ULS E TIME Ms 27.5 Ms 3.25 Ms

INJECTOR V OLTA G E VOLTS 11.4 V 14.0 V

AIR / FUE L RATIO % 0.0 : 1 14.7 : 1

PURGE PWM % 0 % 10 %

EGR POS. COMMANDED % 0% 0%

EGR POS. FEEDBACK. % 0% 0%

EGR PINTLE S ENSOR VOLTS VOLTS 0.6 VOLT 0.6 V O LT

BATTERY VOLTAGE VOLTS 11. 3 V 14.0 V

REFERENCE V O LTS VOLTS 4.99 V 4.99 V

3X SIGNAL MISSING / PRESENT MISSING PRESENT

18X SIGNAL MISSING / PRESENT MISSING PRESENT

CAM SIGNAL MISSING / PRESENT MISSING PRESENT

IAC POSITION STEPS 169 STEPS 22 STEPS

LITERS P ER HOUR L/HR 00.00 1 – 2 L/Hour

IDL E RPM VAR IANT. RPM 0 R PM 0 RPM

TECH 2 SCAN DATA ENGINE STREAM (CONTINUED)

TYPICAL DATA VALUE S

SCAN POSITION Q

Q UNITS DISPLAYED R

R IGNITION "ON" T

T ENGINE RUNNING U

SPARK MODE BYPASS/EST BYPASS EST

SPARK ADVANCE DEGREES BTDC 14 ° BTDC + 14° BTDC

KNOCK SIGNAL CYLINDER 1 NONE/KNOCK

DETECTED NONE NONE

KNOCK SIGNAL CYLINDER 2 NONE/KNOCK

DETECTED NONE NONE

KNOCK SIGNAL CYLINDER 3 NONE/KNOCK

DETECTED NONE NONE

KNOCK SIGNAL CYLINDER 4 NONE/KNOCK

DETECTED NONE NONE

KNOCK SIGNAL CYLINDER 5 NONE/KNOCK

DETECTED NONE NONE

KNOCK SIGNAL CYLINDER 6 NONE/KNOCK

DETECTED NONE NONE

KNOCK SIGNAL ANY CYLINDER KNOCK/NONE NONE NONE

KNOCK RETARD # OF DEGREES 0 ° 0 °

KNOCK RETARD CYLINDER 1 # OF DEGREES 0 ° 0 °

KNOCK RETARD CYLINDER 2 # OF DEGREES 0 ° 0 °

KNOCK RETARD CYLINDER 3 # OF DEGREES 0 ° 0 °

KNOCK RETARD CYLINDER 4 # OF DEGREES 0 ° 0 °

KNOCK RETARD CYLINDER 5 # OF DEGREES 0 ° 0 °

KNOCK RETARD CYLINDER 6 # OF DEGREES 0 ° 0 °

TCC SOLENOID ON / OFF OFF OFF

VEHICLE SPEED KM / H 0 KM/H 0 KM/H

A/C REQUEST ON /OFF OFF OFF

A/C CLUTCH ON /OFF OFF OFF

A/C PRESS. VOLTS VOLTS 1 - 2 V 1 - 2 V

A/C PRE S SURE SENS OR kP a 352 kPa 600 - 700 kPa A/C OFF

800 - 1000 kPa A/C ON

HIGH SPEED FAN ON / OFF OFF OFF

LOW SPEED FAN REQUEST ON / OFF OFF OFF

THEFT STATUS NO START/START START START

STARTER RELAY OFF/ON ON ON

FUEL PUMP RELAY ON / OFF OFF ON

CRANK TIME SEC 0.0 SEC 0.5 SEC

DTC STA T US NO DTC(s)/

DTC(s) SET NO DTC(s) NO DTC(s)

TIME FROM START TIME 0:00:00 VARIES

CHECK P OWERTRAI N

LAMP OFF/ON ON OFF

REQUESTE D TORQUE Nm 214 Nm 642Nm

(N.m WILL VARY DEPENDING ON T HE

ABS/ETC CONTROL MODULE

REQUEST ED TORQUE)

ACTUAL TORQUE Nm 0 Nm 35-45 N.m

(Nm WILL CLOSELY FOLLOW

REQUEST ED TORQUE DURING

TRACTION CONT ROL)

LOW OIL PRESSURE NO/YES YES NO

LPG SWITCH OFF/ON OFF OFF

LPG FUEL ENABLE NO/YES YES YES

FUEL PETROL / LPG LPG LPG

LPG FUEL CONTROL VALVE 0-100 % 100% 40%

LPG MODE ENABLED NO/YES NO YES

LPG LOW PETROL CUTOUT NO/YES NO NO

LPG SMART SOLENOID

ENABLED ON/OFF OFF OFF

5. SPECIFICATIONS

LPG cylinder ‘fillable’ capacity - Sedan................................................ 74 litres (± 2 litres)

LPG tank ‘fillable’ capacity - Wagon .................................................... 60 litres (± 2 litres)

Converter primary pressure ................................................................. 1 - 1.5 psi (7 - 10 kPa)

Converter secondary pressure ............................................................ Negative 1 - 1.5 inches W.C

(Negative 24 - 38 mm W.C.)

Contents gauge sender unit resistance ............................................... Empty : 40 Ohms

Full: 255 Ohms

Fuel Control Valve (FCV) resistance ................................................... 19 - 21 Ohms @ 20°C

LPG lock-off coil resistance ................................................................ 17 - 27 Ohms @ 20°C

LPG lock-off pressure rating................................................................ 1200 kPa

Spark plug gap..................................................................................... 1.4mm

6. TORQUE WRENCH SPECIFICATIONS

All torque wrench specifications are as detailed in LPG System (Sedan) and (Wagon) of the VT Series Service

manual.

7. SPECIAL TOOLS

All special tools that are required f or VX series Models with LPG are included in the VT Series I Servic e Inform ation

– LPG System, VT Sedan, with LPG.