Engine Management GEN IV V8 – General Information Page 6C4-1–1
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Section 6C4-1
Engine Management GEN IV V8 –
General Information
ATTENTION
Before performing any service operation or other procedure described in this Section, refer to Section 00
Warnings, Cautions and Notes for correct workshop practices with regard to safety and/or property damage.
1 General Information ...............................................................................................................................3
1.1 Introduction............................................................................................................................................................ 3
1.2 Emission Control................................................................................................................................................... 4
Euro 3 Emissions Standards ................................................................................................................................ 4
2 Component Locations ...........................................................................................................................5
2.1 Cylinder Numbering............................................................................................................................................... 5
2.2 Engine Compartment............................................................................................................................................. 6
2.3 Engine..................................................................................................................................................................... 7
2.4 Interior .................................................................................................................................................................... 9
3 System Operation.................................................................................................................................10
3.1 Fuel Delivery System........................................................................................................................................... 10
Fuel System Modes of Operation................................................................................................................. 11
Starting Mode................................................................................................................................................... 11
Clear Flood Mode............................................................................................................................................. 11
Run Mode......................................................................................................................................................... 11
Acceleration Mode............................................................................................................................................ 12
Power Enrichment Mode.................................................................................................................................. 12
Deceleration Mode........................................................................................................................................... 12
Fuel Shut-off Mode........................................................................................................................................... 12
Engine Protection Mode................................................................................................................................... 12
Battery Voltage Correction Mode..................................................................................................................... 12
Limp Mode ....................................................................................................................................................... 12
Speed Density Mode........................................................................................................................................ 12
Catalyst Protection Mode................................................................................................................................. 13
Short and Long Term Fuel Trim.......................................................................................................................... 13
3.2 Electronic Ignition (EI) System........................................................................................................................... 14
3.3 Throttle Actuator Control (TAC) System............................................................................................................ 15
Description......................................................................................................................................................... 15
Throttle Body Relearn Procedure..................................................................................................................... 16
3.4 Emission Control Systems.................................................................................................................................. 17
Evaporative Emission Control System....................................................................................................... 17
Engine Ventilation System............................................................................................................................. 17
3.5 Electric Cooling Fans.......................................................................................................................................... 18
3.6 Torque Management............................................................................................................................................ 19
4 System Components............................................................................................................................20
4.1 A/C Refrigerant Pressure Sensor....................................................................................................................... 20
4.2 Brake Pedal Switches.......................................................................................................................................... 21
Stop Lamp and BTSI Switch Assembly...................................................................................................... 21
Cruise Control Release and Extended Brake Trav el Switch Assembly............................................. 21
4.3 Cruise Control System ........................................................................................................................................ 22
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4.4 Camshaft Position (CMP) Sensor....................................................................................................................... 23
4.5 Clutch Pedal Travel Switch................................................................................................................................. 24
4.6 Crankshaft Position (CKP) Sensor..................................................................................................................... 25
4.7 Engine Coolant Temperature (ECT) Sensor ...................................................................................................... 26
4.8 Engine Oil Pressure (EOP) Sensor..................................................................................................................... 27
4.9 Fuel Rail Assembly.............................................................................................................................................. 28
Fuel Injectors..................................................................................................................................................... 28
4.10 Heated Oxygen Sensors (Heated O2 Sensor).................................................................................................... 29
4.11 Ignition Coils / Modules....................................................................................................................................... 31
4.12 Intake Air Temperature (IAT) Sensor.................................................................................................................. 32
4.13 Knock Sensors (KS) ............................................................................................................................................ 33
4.14 Manifold Absolute Pressure (MAP) Sensor....................................................................................................... 34
4.15 Reverse Inhibit Solenoid..................................................................................................................................... 35
4.16 Air Intake System................................................................................................................................................. 36
Mass Air Flow (MAF) Sensor............................................................................................................................... 36
Intake Air Temperature (IAT) Sensor.................................................................................................................. 37
4.17 Engine Control Module (ECM) ............................................................................................................................ 38
Self Diagnosis ................................................................................................................................................... 38
Programming..................................................................................................................................................... 38
4.18 Vehicle Speed Sensor (VSS)............................................................................................................................... 40
5 Abbreviations and Glossary of Terms...............................................................................................41
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1 General Information
The GEN IV V8 engine management system
incorporates functions and components that
could cause personal injury or vehicle
damage. Refer to Section 6C4-2 GEN IV V8
Engine Management – Diagnostics, and
Section 6C4-3 GEN IV V8 Engine Management
– Service Operations, before attempting any
diagnosis or repairs.
1.1 Introduction
The GEN IV V8 engine incor porates an electronic powertrain management system. This Section describes the operation
and locations of the various systems and components encompassed by the powertrain management system.
The powertrain management system is controlled b y the engine control module (ECM) which is located on the left-h an d
side of the engine compartment.
The ECM controls:
• the fuel injection system,
• ignition timing and dwell,
• engine throttling,
• manual transmission functions,
• the engine cooling fans, and
• the air-conditioner compressor clutch ( where fitted).
The engine incorporates sensors that provide input to the ECM, and a range of components that perform functions as
commanded by the ECM, refer to Figure 6C4-1 – 6.
The engine management system has a self diagnostic capability, as well as connections to enable diagnosis of faults. If
the ECM recognises operational problems it can al ert the driver via the Malfunction indicator lamp in the instrument
cluster multi-function display. The ECM also interfaces with other systems in the vehicle as required.
The vehicle incorporates a the ft deterrent system. When the ignition switch is turned from off to on, the body control
module (BCM) will transmit serial security data to the ECM via the powertrain interface module (PIM). If the data
matches, the ECM and PIM will enable the starter relay and fuel injection. For further inform ation and diagnosis of the
theft deterrent system, refer to Section 12J Body Control Module.
For further information on the PIM, refer to Section 6E3 Powertrain Interface Module – GEN IV V8.
For further information on the air-conditioni ng system, refer to Section 2A HVAC Climate Control – Description and
Operation.
For the location of fuses, fusible links and relays, refer to Section 12O Fuses, Relays, an d Wiring Harnesses.
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1.2 Emission Control
Euro 3 Emissions Standards
The vehicle has been configured to comply with Euro 3 vehicle emissions standards. Euro 3 is a European standard
which sets vehicle emissions targets to compel vehicle manufacturers to reduce harmful vehicle emissions such as
carbon monoxide (CO), hydrocarbons (HC) and the various oxides of nitrogen (NOx).
Australian Design Rule 70/01 implements the Euro 3 exhaust and evaporative emissions requirements for light vehicles
to reduce air pollution. The following tests are prescribed:
• average tailpipe emissions after a cold start,
• carbon monoxide emission at idling speed,
• emission of crankcase gases,
• evaporative emissions, and
• durability of pollution-control d evices.
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2 Component Locations
2.1 Cylinder Numbering
Engine cylinder identification follows the international
standard OBD II. This standard calls for the engine cylinder
bank number one to be identified by the location of cylinder
number one. Therefore the numbering for the GEN IV V8
engine is:
• 1, 3, 5, 7 – Left-hand side (Bank 1),
• 2, 4, 6, 8 – Right-hand side (Bank 2).
The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3.
Figure 6C4-1 – 1
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2.2 Engine Compartment
Figure 6C4-1 – 2
Legend
1 Engine Control Module (ECM)
2 Mass Air Flow (MAF) Sensor 3 Air-conditioner Refrigerant Pressure Sensor
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2.3 Engine
Figure 6C4-1 – 3
Legend
1 Manifold Air Pressure sensor(MAP)
2 Evaporative Canister Purge Solenoid
3 Ignition Coils/Modules Assembly, 2 Places
4 Heated Oxygen Sensor (Heated O2 Sensor), 2 places
5 Heated Oxygen Sensor (Heated O2 Sensor), 2 places
6 Crankshaft Position (CKP) Sensor
Engine Management GEN IV V8 – General Information Page 6C4-1–8
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Figure 6C4-1 – 4
Legend
1 Evaporative Canister Purge Solenoid
2 Knock Sensor, 2 Places
3 Engine Coolant Temperature (ECT) Sensor
4 Camshaft Position (CMP) Sensor
5 Engine Oil Pressure (EOP) Sensor
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2.4 Interior
Figure 6C4-1 – 5
Legend
1 Check Powertrain Icon
2 Data Link Connector (DLC)
3 Clutch Pedal Cruise Control Cancel Switch
4 Clutch Pedal Position Switch
5 Cruise Control Release and Extended Brake Travel Switch Assembly
6 Stop Lamp Switch
7 Accelerator Pedal Assembly
8 Transmission Control Moduel
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3 System Operation
The ECM is the control centre of the GEN IV V8 powertrain management s ystem and constantly monitors and evaluates
inputs from various sensors and switches. Based on these inputs, the ECM controls the oper ation of the powertrain
management system. Refer to Figure 6C4-1 – 6 for the illustration of the inputs and outputs of the ECM.
Figure 6C4-1 – 6
3.1 Fuel Delivery System
Unleaded fuel must be used to ensure correct emission parameters and engine o peration. Leaded fuel can damage the
emission control system and can result in loss of emission warranty. Using unleaded fu el will also minimise any spark
plug fouling and e xtend engine oil life.
The function of the fuel and air control s yste m is to manage the delivery of fuel and air mixture to each cylinder,
optimising the performance and t he driveability of the engine under all conditions. A modular fuel pump and sender
assembly delivers fuel from the fuel tank and provides infor mation on the fuel level.
The fuel supply system is a single lin e, on-demand design. With the fuel pressure regulator incorporated into the modular
fuel pump and sender assembly, the need for a return pipe from the engine is eliminated. Havin g a sing le line fuel supply
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system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine. In reducing the internal
temperature of the fuel tank, lower evaporative emissions are achieved.
An electric fuel pump contained in the modu lar fuel pump and sender assembly provides fuel at a press ure above the
regulated pressure which is supplied to the fuel rail. The fuel is then distributed through the fuel rail to eight injectors
located directly above each cylind er’s two intake valves. A fuel pump relay allows the ECM to control the fuel pump.
The ECM controls each fuel in jector by energising the injector coil for a brief period once every other engine revolution.
The length of this brief period is carefully calculated by the ECM to deliver the correct amount of fuel for optimum engine
performance and emission control. The period of time when the injector is energised is called the pulse width and is
measured in milliseconds (thousandths of a second).
While the engine is running, the ECM is constantly monitoring the inputs and recalculating the appropriate pulse width for
each injector. The pulse width calculation is based on:
• the injector flow rate,
• mass of fuel passed by the energised injector per unit of time,
• the desired air/fuel ratio, and
• actual air mass in each cylinder.
The calculated pulse is timed to occur as each cylinder’s intake valve is closing to provide enough time for the fuel to
atomise completely and mix with the intak e air. Each injector is energised individually in the engine firin g order, which is
known as sequential fuel injection.
Fuel System Modes of Operation
The ECM has several operati ng modes for fuel control, depending on the information received from the sensors.
Starting Mode
When the ignition s witch is turned on, the EC M energises the fuel pump circuit to operate the fuel pump which builds
pressure in the fuel system. If the ECM does not receive reference pulses from the cranks haft position sensor, the fuel
pump circuit will be de-energised after 2 seconds. When the ignition s witch is moved to the START position, the fuel
pump circuit will remain (or become) energised by the ECM once reference pulses are received from the crankshaft
position sensor.
As the engine begins to turn, a prime pulse may be injected to speed starting. As soon as the ECM can determine where
in the firing order the engine is, the ECM begins p ulsi ng the injectors. The ECM also monitors mass air flow, intake air
temperature, engine coolant temperature, and throttle position in order to determine the required injector pulse width for
starting.
Clear Flood Mode
If the engine is flooded with fuel during cranking and will not start, the clear flood mode can be manuall y selected by
depressing the accelerator pedal to wide open throttle (WOT). In this mode, the ECM will completely turn off the
injectors, and will maintain this state during engine cranking as long as the ECM detects a WOT condition with engine
speed below 1,000 RPM.
Run Mode
The ECM changes to run mode when it reaches 480 RPM after being started. The run mode has two sub-modes called
Open Loop and Closed Loop.
Open Loop Mode
In open loop, the ECM ignores the signals from the heated oxygen sensors (Heated O2 Sensor), and calculates the
required injector puls e width based primarily on inputs from the mass air flo w (MAF), Intake Air Temperature (IAT), and
Engine Coolant Temperature (ECT) sensors. In open loop the calculated pulse width may give an air/fuel ratio other than
the ideal 14.7 to 1, for example when the engine is cold a richer mixture is needed. The system will stay in the open loop
mode until the Heated O2 Sensor produces a usable output.
Closed Loop Mode
Once the Heated O2 Sensor reaches operating temperature and starts producing its own signal volta ge output, the ECM
switches to closed loop mode. In closed lo op mode, the ECM initially calculates injector pulse width based on the same
sensors used in open loop a nd additionally, uses the oxyge n sensor signals to modify and fine tune the fuel p ulse width
calculations to precisely maintain the ideal 14.7 to 1 air/fuel ratio.
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Acceleration Mode
The ECM monitors changes in the acceler ato r pedal position (APP) and MAF sensor signals to determine when the
vehicle is being accelerated. The ECM will then increase the injector pulse width in order to provide more fuel
accordingly.
Power Enrichment Mode
Similar to Acceleration Mode, the ECM enters power enrichment mode when the ECM detects a large change in the
accelerator pedal position, providing extra fuel to the cylinders as required.
Deceleration Mode
The ECM monitors changes in the APP and MAF sensor signals to determine when the vehicle is being decelerated. The
ECM will then decrease injector pulse width, or even shut the injectors off for short periods, to reduce exhaust emission s
and improve fuel econom y.
Fuel Shut-off Mode
The ECM has the ability to completely turn off some or all of the injectors when certain conditions are met. These fuel
shut-off modes allow the ECM to protect the engine from damage a nd to also improve the vehicle's driveability.
The ECM will disable all eight injectors under the following conditions:
• ignition off – to prevent engine run-on,
• ignition on but no ignition refe rence signal – prevents flooding or backfiring,
• at high engine speed – above the red line (rev limiter),
• at high vehicle speed – above the rated tyre speed (vehicle speed limiter), or
• extended high speed closed throttle coast-down – reduces engine emissions and increases engine braking.
The ECM will selectivel y disable the injectors und er the following conditions:
• torque management enabled – transmission shifts or abusive manoeuvres, or
• traction control enabled – in c onjunction with brake application.
Engine Protection Mode
Engine protection mode is en gaged to protect engine components from friction damage i n the eve nt of an engine over-
temperature condition being detected by the ECM.
When the ECM is in engine pr otection mode, fuel injectors are systematically disable d and re-activated. The injectors
that have been shut down allow the air being drawn into the engine to assist with engine cooling.
Battery Voltage Correction Mode
The ECM can provide compensatio n to main tain acceptable vehicle driveability when the ECM sees a low battery voltage
condition. The battery voltage adjustment is necessary since the changes in the voltage across the injector affect the
injector flow rate.
The ECM compensates by performing the following functions:
• increases the injector pulse width to maintain the correct amount of fuel being de livered, and
• increases the idle speed to increase the gen erator outp ut.
Limp Mode
In the event of a major internal problem, the ECM is equipped with a back-up fuel strategy for limp mode that will run the
engine until service can b e performed.
Speed Density Mode
If the ECM detects a malfunction with the MAF sensor circuit, the ECM will default to speed de nsity fuel management. In
speed density mode, the ECM will rely primarily on the MAP sensor instead of the MAF sensor signal to control engine
fuelling.
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Catalyst Protection Mode
During sustained heav y loads, the ECM increases the pulse width to the injectors to provide e xtra fuel to prevent the
catalytic converters from overheating.
Short and Long Term Fuel Trim
Short term fuel trim (STFT) represents short term corrections to the fuel injector pulse width calculations based on the
HEGO sensor input signals to the ECM. STFT is not active until the Heated O2 Sensor is at operational temperature.
By using the Heated O2 Sensor as the main reference point for control of engine fuelling, the ECM can more accurately
control the air / fuel ratio. This is because when using STFT the ECM reacts to actual results from combustion, and not
expected results (base settings). STFT is used by the ECM to make quick changes to the fuel injector pulse width over a
short period of time.
The values for STFT can be viewed as a percentage using TECH 2. Values greater tha n 0% indicate that the ECM is
increasing injector pulse width, and negative values (less than 0%) indicate reduce d injector pulse widths.
Long term fuel trim (LTFT) represents long term corrections to the fuel injector pulse width calculations based on the long
term trend of the STFT calculations. T he ECM monitors the STFT and will adjust the long term trend of the fuel injector
pulse width when the STFT has been at a particular value for a certain period of time. LTFT is not active until the Heated
O2 Sensor is at operational temperature.
LTFT compensates for engi ne and component wear, condition of filters, and any other system variations.
The LTFT function of the ECM is divided into 23 cells arranged by MAP sensor readings and engine RPM. Each cell
corresponds to a region on a MAP vs. RPM table. A value of 0% in a given cell indicates that no fuel adjustment is
needed for that engine load and speed condition. As the engine moves through its operating range, the LTFT changes to
the relevant cell. The ECM will read the LTFT value in each cell and adjust the fuel in jector base pulse width accordingly.
As the LTFT changes cell so does STFT, however STFT will only make short term corrections in the cell that the LT FT is
operating in. The ST FT adjustments occur after the LTFT corrections are made. In this way, the STFT can make minor
corrections to the injector pulse width in each cell quicker than if the corrections were made from 0% each time the ECM
changed cell.
If STFT and LTFT are both set at their maximum value limit, the fuel control system is out of the limits of control. This will
result in the system going into open loop op eration and a Diagnostic T r ouble Code to be set.
The values for LTFT can be viewed as a percentage using TECH 2. Values greater than 0% indicate that the ECM is
increasing injector pulse width, and negative values (less than 0%) indicate reduce d injector pulse widths.
TECH 2 has the ability to rese t all LTFT cells to 0%.
All LTFT cell values are reset to 0% when long term memory power to the ECM is removed.
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3.2 Electronic Ignition (EI) System
The electronic ignition s ystem provides a sp ark to ignite the compressed air/fuel mixture at the correct time. T he ECM
maintains correct spark timing and dwell for all driving conditions. The ECM calculates the optimum spark parameters
from information received from the various sensors and triggers the appropriate ignition module / coil to fire the spark
plug.
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3.3 Throttle Actuator Control (TAC) System
Description
The throttle actuator control (TAC) system is used to impr ov e emissions, fuel economy and driveability. The TAC system
deletes the mechanical link between the accelerator pedal and the throttle plate an d eliminates the need for a cruise
control module and idle air co ntrol motor. The TAC system consists of:
• an accelerator pedal assembly which includes:
• accelerator pedal,
• accelerator pedal position (APP) sensor 1,
• accelerator pedal position (APP) sensor 2;
Figure 6C4-1 – 7
To avoid serious personal injury, never
attempt to rotate the throttle plate manually
whilst the throttle body harness connector is
connected to the throttle bod y.
• a throttle body assembly which includes:
• throttle position (TP) sensor 1,
• throttle position (TP) sensor 2,
• throttle actuator control motor, and
• throttle plate;
• an engine control module (ECM).
Figure 6C4-1 – 8
The ECM monitors the accelerator pedal p osition through the two APP sensors and. The ECM processes this
information along with other system sensor inputs to command the thr ottle plate to a certain position. This throttle
position sent via a pulse width modulated signal to the throttle bod y.
A direct current motor called the throttle actuator control motor controls the throttle plate. The ECM can operate this
motor in the forward or reverse direction by controlling battery voltage and/or ground to two internal drivers. When there
is no current flowing to the actuator motor, the throttle plate is held at a rest position of 7 percent open using a constant
force return spring.
The ECM monitors the throttle plate angle through two TP sensors. Using this information, the ECM can precisely adjust
the throttle plate.
The ECM performs diagnostics that monitor the voltage levels of both APP sensors, both TP sensors and the throttle
actuator control motor circuit. It also monitors the spring return rate. T hese diagnostics are performed at different times
based on whether the engine is running, not running, or whether the ECM is currently in a throttle body relearn
procedure.
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Two sensors within the accelerator ped al assembly and throttle body asse mbly are used to provide redundancy. If a
malfunction is detected, the throttle plate is moved to a pre-determined po sition.
Every ignition cycle, the ECM performs a quick throttle return spring test to ensure the throttle plate can return to the 7
percent rest position from the 0 percent position. This is to ensure that the throttle plate can be brought to the rest
position in case of an actuator motor circuit failure.
Throttle Body Relearn Procedure
The ECM stores values that include the lowest possible TP sensor positions (0 percent), the rest positions (7 percent),
and the spring return rate. These values will only be erased or overwritten if the ECM is reprogrammed or if a throttle
body relearn procedure is performed.
NOTE
If the battery has been disconnected, the ECM
performs a throttle body relearn procedure once
the battery has been reconn ected and the ig nition
turned on.
The ECM performs a throttle body relearn procedure anytime the ignition is turned on and the following conditions have
been met:
• the engine has been off for longer tha n 29 seconds,
• the engine speed is less than 40 RPM,
• the vehicle speed is 0 km/h,
• the engine coolant temperature (ECT) is between 5 – 60°C; if T ECH 2 is used to perform the relearn procedure, the
ECT is between 5 – 100°C
• the intake air temperature (IAT) is more than 5 – 60°C; if TECH 2 is used to perform the relearn procedure, the IAT
is between 5 – 100°C,
• the APP sensor angle is less than 15 percent, and
• ignition voltage is more than 10 volts.
The throttle body relearn procedur e is performed 29 seconds after the ignition is turned on. The ECM commands the
throttle plate from the rest position (7 percent open) to full closed (0 percent), and then to around 10 percent open. This
procedure takes about 6 – 8 seconds. If any faults occur in the TAC system, a DTC sets. At the start of this procedure,
the TECH 2 TAC Learn Counter parameter should displ ay 0, and then count up to 11 after the procedure is completed. If
the counter did not start at 0, or if the counter did not end at 11, a fault has occurred and a DTC should set.
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3.4 Emission Control Systems
Evaporative Emission Control System
The evaporative emission con t rol system used is the
activated carbon (charcoal) canister storage method. Fuel
vapour is drawn from the fuel tank into the canister where it
is held by the activated carbon until the ECM commands the
Evaporative Emission (EVAP) purge solenoid valve to open.
Figure 6C4-1 – 9
The ECM energises the EVAP purge sole noid valve by
applying a Pulse Width Modulated (PWM) ground to the
EVAP purge solenoid valve control circuit.
When the ECM commands the EVAP valve (1) to open, the
fuel vapours are drawn from the canister line (2) into the
intake manifold where it is consumed in the normal
combustion process.
The ECM energises the EVAP valve when the appropriate
conditions have been met.
The EVAP purge PWM duty cycle varies according to
operating conditions determin ed by mass air flow, fuel trim
and intake air temperature. For further information on the
evaporative emission control system, refer to
Section 8A1 Fuel System.
Figure 6C4-1 – 10
Engine Ventilation System
The engine ventilation system contains an oil separator (1)
and fixed internal flow-restricting orifice (2) located inside
the front right-hand corner of the valley cover. A hose is
routed from the valley cover to the intake manifold.
A breather pipe is routed from the intake manifold to the
right-hand camshaft cover and provides fresh filtered air
from the intake duct to the engine.
For further information of the engine ventilati on system,
refer to Section 6A4 Engine Mechanical – GEN IV V8.
Figure 6C4-1 – 11
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3.5 Electric Cooling Fans
The ECM controls the operation of two dual-speed electric engine cooling fans. The ECM operates the fans at either low
or high speed based on inputs from engine coolant temperature, vehicle spee d and air-conditioner request. For further
information on cooling fan ope ration, refer to Section 6B3 Engine Cooling – GEN IV V8.
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3.6 Torque Management
Torque management is a function of the ECM that reduces engine power during certain cond itions.
Torque management is perform ed for the following reasons:
• to prevent over stressing the powertrain components,
• to prevent damage to the vehicle during certain abusive manoe uvres, and
• to reduce the engine speed when the IAC is out of the normal operating range.
The ECM monitors the following sensors and engine parameters to calcu late the engine output torque:
• air/fuel ratio,
• mass air flow,
• manifold absolute pressure,
• intake air temperature,
• spark advance,
• engine speed,
• engine coolant temperatur e, and
• A/C clutch status.
The ECM monitors engine speed to determine if torque reduction is required. T he ECM retards the spark as appropriate,
to reduce the engine torque output if torque reduction is required. The ECM also shuts off the fuel to certain injectors in
order to reduce the engine power in the instance of an abusive manoeuvre.
The following are instances when an engine power reduction is likely to be experienced:
• during transmission up-shifts and do wnshifts,
• during heavy acceleration from a standing start,
• if the IAC is out of the normal operating range, or
• if the driver is performing harsh or abusive manoeuvres, such as shifting into gear at high throttle angles or shifting
the transmission from reverse to drive in orde r to create a rocking motion.
The driver is unlikely to notice the torqu e mana gement actions in the first two instances. The engine power output will be
moderate at full throttle in the other two instances.
The ECM calculates the amount of spark retard that is necessary to reduce the engine power by the desired amount.
The ECM disables the fuel injectors for cylinders 1, 4, 6, and 7 if an abusive manoeuvre occurs.
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4 System Components
4.1 A/C Refrigerant Pressure Sensor
The ECM applies a positive 5 volts reference voltage and
ground to the air-conditioning (A/C) refrigerant pressure
sensor. The A/C pressure sensor provi des signal voltage to
the ECM that is proportional to the A/C refrigerant pressure.
The ECM monitors the A/C pressure sensor signal voltage
to determine the refrigerant pressure.
• The A/C pressure sensor volt age increases as the
refrigerant pressure increases.
• When the ECM detects that the refrigerant pressure
exceeds a predetermined value, the ECM activates
the cooling fans to reduce the refrigerant pre ssure.
• When the ECM detects that the refrigerant pressure is
too high or too low, the ECM disables the A/C clutch to
protect the A/C compressor from damage.
Figure 6C4-1 – 12
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4.2 Brake Pedal Switches
Stop Lamp and BTSI Switch Assembly
The stop lamp and BTSI s witch assembly (1) is located o n
the brake pedal support.
The Engine Control Module (ECM) uses the stop lamp
switch signal voltage to determine when the brake pedal is
depressed.
The ECM uses this input for torque management, for cross-
referencing the stop lamp switch against the cruise control
cancel switch for correct operation, etc. For further
information on torque management, refer to
3.6 Torque Management.
The stop lamp switch is a normally open switch with the
brake pedal at rest.
Figure 6C4-1 – 13
Cruise Control Release and Extended Brake Trav el Switch Assembly
The cruise control release and extended brake travel switch assembly (2) is located on the brake pedal support.
Refer to Figure 6C4-1 – 13
The engine control module (E CM) uses the cruise control release switch signal voltage to determine when the brake
pedal is depressed. T he ECM uses this input to cancel cruise control operation, for cross-referencing the cruise control
release switch against the stop lamp s witch for correct operation, etc.
The engine control module (E CM) uses the extended brake travel switch signal voltage to determi ne when full brake
pedal travel has been achieved. The ECM uses this input to compensate for the air being used by the brake booster.
Both of these switches are normally closed when the brake pedal is in the rest position, opening when the pedal is
pressed. Activation of this switch removes the signal to the ECM.
For further information on the cruise control system, refer to 4.3 Cruise Control System.
Engine Management GEN IV V8 – General Information Page 6C4-1–22
Page 6C4-1–22
4.3 Cruise Control System
The cruise control system inte grates with the powertrain control system through the po wertrain interface module (PIM),
and the engine control module (ECM), to control the electronic throttle actuator and main tain the vehicle at the speed set
by the driver.
When the cruise ON-OFF button is pressed, the PIM, on receiving the input from the cruise control switch, outputs a
signal to the ECM, Whitch send a pulse width signal to the throtle body to provide throttle position. The ECM also
provides a signal for the instrument cluster, via the PIM, to inform the user that the cruise control is engaged.
The user activates the cruise control at a desired speed above 40 kph by rotating the cruise control switch assembl y to
SET–DECEL. The ECM receives the input from the cruise control switch. The ECM then sets the desired speed. The
ECM receives all the various inputs required to maintain the correct speed and then controls the throttle plate, depending
on the load on the engine (ascending or descending hills, etc.).
The cruise control is deactivated b y either pressing the brake pedal, clutch pedal or by the cruise control ON-OFF button.
In each of these instances, the ECM receive s an input when any of these switches are activated.
For further information on the cruise control system, refer to Section 12E Cruise Control.
Engine Management GEN IV V8 – General Information Page 6C4-1–23
Page 6C4-1–23
4.4 Camshaft Position (CMP) Sensor
The CMP sensor is used by the ECM to determine the
position of the camshaft. In conjunction with the crankshaft
position sensor, the CMP enables the ECM to determine
engine rotational position.
Figure 6C4-1 – 14
The CMP sensor operates on the dua l-Hall sensing
principle. The sensor contains two Hall elements (1) which
operate in conjunction with a two-track trigger wheel (2) on
the camshaft.
As the tracks on the trigger wheel pass the elements,
magnetic flux affects a voltage in the Hall elements. The
integrated circuit inside the sensor conditions the signal
generated by the Hall eleme nts to provide a rectangular
wave on / off signal to the ECM.
The ECM supplies the CMP sensors with a 12-volt
reference and a ground circui t.
Engine Management GEN IV V8 – General Information Page 6C4-1–24
Page 6C4-1–24
4.5 Clutch Pedal Travel Switch
There are two clutch pedal switch assem blies; the cruise
control cancel switch (1) and the clutch pedal position switch
(2).
The cruise control cancel switch is normally closed when the
clutch pedal is at rest, opening when the pedal is pressed.
Activation of this switch removes the signal to the ECM
which will then deactivate the cruise co ntrol. F or further
information on the cruise control system, refer to
Section 12E Cruise Control.
The clutch pedal position switch is normally open when the
clutch pedal is at rest, closing when the pedal is fully
pressed. Activation of this switch sends a signal to the
ECM which will then allow operation of the starter motor.
For further information on the starting system, refer to
Section 6D3-2 Starting System – GEN IV V8.
Figure 6C4-1 – 15
Engine Management GEN IV V8 – General Information Page 6C4-1–25
Page 6C4-1–25
4.6 Crankshaft Position (CKP) Sensor
In conjunction with the camshaft position sensor, the
crankshaft position (CKP) sensor enables th e ECM to
determine engine rotational position. The CKP is also used
to determine engine speed (RPM).
Figure 6C4-1 – 16
The CKP sensor operates on the dual-Hall sensing
principle. The sensor contains two Hall elements (1) which
operate in conjunction with a two-track trigger wheel (2) on
the crankshaft (3).
As the tracks (4) on the trigger wheel pass the elements,
magnetic flux affects a voltage in the Hall elements. The
integrated circuit inside the sensor conditions the signal
generated by the Hall eleme nts to provide a rectangular
wave on / off signal to the ECM.
The ECM supplies the CKP sensors with a 12-volt reference
and a ground circuit.
Figure 6C4-1 – 17
Engine Management GEN IV V8 – General Information Page 6C4-1–26
Page 6C4-1–26
4.7 Engine Coolant Temperature (ECT)
Sensor
The engine coolant temperature (ECT) sensor is a
thermistor (a resistor that changes value based on
temperature) mounted in the engine coolant stream. Low
engine coolant temperature produces a high sensor
resistance (29 kΩ at –20° C) while high engine coolant
temperature causes low sensor resistance (180 Ω at
100° C).
Figure 6C4-1 – 18
The ECM uses a dual pull up resistor network to increase
the resolution through the entire operating range of engine
coolant temperature. When the coolant temp erature is less
than 51° C, both the 4K and 348 ohm resistors are used (A) .
When the coolant temperature reaches 51° C, the ECM
switches a short across the 4K resistor and only the 348
ohm resistor is used (B).
As the engine warms, the sensor resistance becomes less
and the voltage at the ECM coolant temper ature sensor
signal terminal should decrease from approximately 4.5
volts when cold to 0.9 volts at 51° C.
At this temperature the ECM switches the short across the
4k resistor; the voltage will then rise to 3.5 volts. The voltage
will again decrease as the coolant temperature increases
until at normal engine operating temperature (95° C), the
voltage should be less than 2.0 volts.
Figure 6C4-1 – 19
Engine Management GEN IV V8 – General Information Page 6C4-1–27
Page 6C4-1–27
4.8 Engine Oil Pressure (EOP) Sensor
The engine oil pressur e (EOP) sensor measures engine oil
pressure. When the EOP sensor signal is below a certain
value, which increases with RPM, the ECM activates the
Check Oil warning icon in the i nstrument cluster multi-
function display (MFD).
Figure 6C4-1 – 20
The EOP sensor provides a voltag e signal to the ECM that
is a function of engine oil pressure. It does this through a
series of deformation resistors (1), which change resistance
when a mechanical force is applied. This force is applied to
the resistors by a diaphragm on which the engine oil
pressure acts (2).
The sensor has an internal ev aluation circuit (3) and is
provided with a five volt reference voltage, a ground and a
signal circuit.
Figure 6C4-1 – 21
Engine Management GEN IV V8 – General Information Page 6C4-1–28
Page 6C4-1–28
4.9 Fuel Rail Assembly
The fuel rail assembly is mou nted on th e lower intake
manifold and distributes fuel to each c ylinder through
individual fuel injectors. The fuel rail assembly consists of:
• eight individual fuel injectors (1),
• the pipe (2) that carries fuel to each injector, and
• a fuel pressure test port (3)
Figure 6C4-1 – 22
Fuel Injectors
A fuel injector is a solenoid device that is cont rolled by the
ECM. The eight injectors deliver a precise amount of fuel
into the intake ports as requir ed by the engine. The injectors
are supplied with igniti on voltage through the EFI relay, and
are switched to ground by the ECM.
Figure 6C4-1 – 23
The fuel port (1) connects to the fuel rail. A strainer (2) is
provided in the port to protect the injector from fuel
contamination.
In the de-energised state (no voltage), the valve needle and
sealing ball assembly (3) are held against a cone-shaped
valve seat (4) by spring force (5) and fuel pressure.
When the injector is energise d by the ECM, the valve
needle, which has an integr al armature, is moved upward by
the injector solenoid’s magnetic field, un-seating the ball.
An orifice plate (6), located at the base of the injector has
several small holes which provide very fine atomisation of
the fuel. The plate is insensitive to fuel de posits ensuring
reliable fuel delivery.
The fuel is directed at each of the intake valves, causing the
fuel to become further vaporised before entering the
combustion chamber.
Figure 6C4-1 – 24
Engine Management GEN IV V8 – General Information Page 6C4-1–29
Page 6C4-1–29
4.10 Heated Oxygen Sensors (Heated O2
Sensor)
The heated oxygen sensors (Heated O2 Sensor) are mounted in the exhaust pipe and enable the ECM to measure
oxygen content in the exhaust stream. The ECM uses this information to accurately control the air / fuel ratio, because
the oxygen content in the exhaust gas is indicative of the air / fuel ratio of engine combustion.
When the sensor is cold, it produces little or no signal voltage; therefore the ECM only reads the Heated O2 Sensor
signal when the Heated O2 Sensor is warm. As soon as the Heated O2 Sensor are warm and outputting a usable signal,
the ECM begins making fuel mixture adjustments based on the Heated O2 Sensor signals. T his is known as closed loop
mode.
GEN IV V8 engines have four Heated O2 Sensors, on e Heated O2 Sensor upstream of the catalytic converter in each
exhaust pipe, and one in each exhaust pipe downstream of the catalytic converter
The Heated O2 Sensor has four wires:
1 The internal heater element supply, which has 12 volts
continually applied whenever the ignition is on.
2 Heater element ground. When the sensors are cold,
the ECM applies maximum current (approximately four
amps) to the heater circuit, which graduall y reduces to
approximately 0.5 amps as the sensor reaches full
operating temperature.
3 Sensor signal to the ECM.
4 Sensor ground.
Legend
1 Four Wire In-line Connector
2 Heater Termination
3 Water Shield Assembly
4 Sensor Lead
5 Sensor Body
6 Seat Gasket
7 Outer Electrode and Protective Coati ng
8 Rod Heater
9 Inner Electrode
10 Zirconia Element
11 Insulator
12 Clip Ring
13 Gripper
Figure 6C4-1 – 25
Engine Management GEN IV V8 – General Information Page 6C4-1–30
Page 6C4-1–30
Measurement is achieved b y comparing the oxygen content
of the exhaust gas (1) to the oxygen content of a referenc e
gas (outside air) using the Nernst principle. Oxygen
molecules from the exhaust gas will accumu late on the
outer electrode (2), while oxygen molecules from the
reference gas will accumulate on the inner electrode (3).
This creates a voltage difference across the ceramic
element (4), between the two electrodes, which is the signal
voltage (V) to the ECM.
The ECM supplies a steady 450 millivolt, very low current
bias voltage to the oxygen sensor signal circuit. When the
sensor is cold and not produc ing any voltage, the ECM
detects only this steady bias voltage. As the sensor b egins
to become warm, its internal resistance decreases and it
begins produci ng a rapidly changing voltage that will
overshadow the steady bias voltage suppli ed by the ECM.
The ECM detects the changing voltage, and can begin
operating in closed lo op.
Figure 6C4-1 – 26
When the fuel system is correctly operating in closed loop
mode, the oxygen sensor voltage output is rapi dly changing
several times per second, fluctuating from approximately
100mV (high oxygen co ntent – lean mixture) to 900mV (lo w
oxygen content – rich mixture). The transition from rich to
lean occurs quickly at about 450-500 mV (A/F ratio 14.7:1,
or lambda = 1). Due to this, these Heated O2 Sensors are
known as two-step or s witching t ype oxygen sensors.
Legend
A Rich Mixture
B A/F Ratio 14.7:1 (Lambda = 1)
C Lean Mixture
D Sensor Voltage
Figure 6C4-1 – 27
Engine Management GEN IV V8 – General Information Page 6C4-1–31
Page 6C4-1–31
4.11 Ignition Coils / Modules
Eight ignition coils, four per cylind er ba nk, are individually
mounted to an ignition coil mountin g bracket that is bolted to
each rocker cover. Each coil has a short high tension
secondary ignit ion wire connecting it the relevant spark plug.
A printed circuit board, or driver module, is integrated with
each coil, and controls the firing of the coil based on in put
from the ECM.
Figure 6C4-1 – 28
The ECM is responsible for maintaining correct spark timing
and dwell for all driving conditions. The ECM calculates the
desired spark parameters from informatio n received from
the various sensors, and triggers the appropr iate ignition
module which then operates the coi l.
The ignition coil / modules are supplied with the following
circuits:
• Ignition feed circuit.
• Ignition control circuit.
• Ground circuit.
• Reference low circuit.
Figure 6C4-1 – 29
Engine Management GEN IV V8 – General Information Page 6C4-1–33
Page 6C4-1–33
4.13 Knock Sensors (KS)
The knock sensor signal is used b y the ECM to provide
optimum ignition timing while minimising engine knock or
detonation.
The knock sensor is tuned to detect the frequency of the
vibration created by combustion knock. The vibration is
transferred through the cylinder block to the knock sensor.
Inside the sensor is a mass (1) that is excited by this
vibration, and the mass exerts a compressive force onto a
piezo-ceramic element (2). The compressive force causes a
charge transfer inside the element, so that an AC voltage
appears across the two outer faces of the element. The
amount of the AC voltage produced is proportional to the
amount of knock. This AC signal voltage to the ECM is
processed by a Digital Signal Noise Enhancement Filter
(DSNEF) module. This DSNEF module, an integral part of
the ECM, is used to determine if the AC signal coming in is
noise or actual detonation.
Figure 6C4-1 – 30
Engine Management GEN IV V8 – General Information Page 6C4-1–34
Page 6C4-1–34
4.14 Manifold Absolute Pressure (MAP)
Sensor
The manifold absolute pressure (MAP) sensor is mounted to
the front of inlet manifold so that its sensing element is
exposed to manifold pressure downstream of the throttle
body.
The ECM sends a 5-volt supply voltage to the MAP sensor.
As the manifold pressure varies, due to changes in engine
load, the output voltage of the sensor also chang es. By
monitoring the sensor output voltage, the control module
determines the manifold pressure.
The MAP sensor is used for the follo wing:
• ignition timing control, and
• speed density fuel manag ement default. Figure 6C4-1 – 31
Engine Management GEN IV V8 – General Information Page 6C4-1–35
Page 6C4-1–35
4.15 Reverse Inhibit Solenoid
The manual transmission is fitted with a reverse inhibit
mechanism that prevents the selection of reverse ge ar when
the vehicle speed is above 8 km/h. If the engine is running
and the vehicle speed is less than 8 km/h, the reverse inhibit
solenoid (1) is energised b y the ECM, all owing selection of
reverse gear.
For more information on the reverse inhibit solenoid, refer to
Section 7B2 Manual Transmission – GEN IV V8.
Figure 6C4-1 – 32
Engine Management GEN IV V8 – General Information Page 6C4-1–36
Page 6C4-1–36
4.16 Air Intake System
The air intake system draws outside air through an air
cleaner assembly (1). The air is then routed throu gh a mass
air flow (MAF) sensor (2) and into the throttle body and
intake manifold. The air is then directed into the intake
manifold runners, through the c ylinder he ads and into the
cylinders.
An arrow marked on the body of the MAF sensor indicates
correct air flow direction. The arrow must point toward the
engine.
Figure 6C4-1 – 33
Mass Air Flow (MAF) Sensor
A heated element type mass air flow (MAF) sensor is
mounted in the air flow stream of the engine intake system.
The MAF sensor measures the mass of the air being
inducted into the engine, and is one of the key signals the
ECM uses to calculate the required fuel quantity to be
injected.
Figure 6C4-1 – 34
Three sensing elements are used in the MAF sensor. One
senses ambient air temperatur e (1) and is mounted in the
lower half of the sensor housing. The ambient temperature
sensor uses two calibrated resistors to establish a voltage
that is a function of ambient temperature.
The other two sensing elements (2) are heated to a
predetermined temperature that is significantly above
ambient air temperature. The t wo heated elements are
connected electrically in para llel and mounted directly in the
air flow stream of the sensor housing.
One sensor is in the top and the other sensor is in the
bottom of the sensor housing. This is done so that the air
meter is less sensitive to upstream airflo w variations that
could affect the flow of air through the housin g.
As air passes over the heated elements during engine
operation, they begin to cool. By measuring the amo unt of
electrical power required to maintain the heated elements at
the predetermined temperature above ambient temperature,
the mass air flow rate can be determined. Figure 6C4-1 – 35
Before being sent to the ECM, the small voltage signal generated in the mass air flow sensor is converted to a frequen cy
signal by a voltage oscill ator, to preserve the accuracy and resolution of the signal.
Engine Management GEN IV V8 – General Information Page 6C4-1–37
Page 6C4-1–37
A large quantity of air passing through the se nsor (such as when accelerating) will be indicated as a high frequency
output. A small quantity of air passi ng through the sensor will be indic ated as a low frequency output (such as when
decelerating or at idle). T ECH 2 displays MAF sensor information in frequency or in grams per second. At idle the
readings should be low and increase with engine RPM.
If a fault occurs in the MAF sensor circuit, the ECM will store a DTC in its memory, and will calculate a substitute mass
air flow signal based on speed density, using the engine speed, Manifold Absolute Pressure, and Intake Air Temperature
signals.
Intake Air Temperature (IAT) Sensor
The MAF sensor also incorporates the intake air temperature (IAT) sensor. The IAT sensor is a thermistor, (a resistor
that changes resistance with changes in temperature). Low intake air temperature produces high resistance in the
sensor, while high intake air temperature caus es low sensor resistance. The IAT sensor (3) is not serviced separately
from the MAF sensor, refer to Figure 6C4-1 – 35.
The ECM provides a 5 volt referenc e signal to the IAT and monitors the return signal which enables it to calculate the
intake air temperature. The ECM uses this signal to make corrections to the operating parameters of the system based
on changes in air intake temperature. The circuit voltage will vary dependin g on the resistance of the IAT sensor. The
voltage will be close to the 5 volt level when the sensor is cold, and will decrease as the sensor warms.
No field service adjustment is necessary or possible with the MAF or IAT sensors.
Engine Management GEN IV V8 – General Information Page 6C4-1–38
Page 6C4-1–38
4.17 Engine Control Module (ECM)
Located at the left side of the engine compartment, the
engine control module (ECM) constantly monitors
information from various sensors and co ntrols the many
powertrain management functions, such as the fuel injection
and ignition systems, to provide optimal performance and
minimal emission output in all driving conditions.
The ECM also controls:
• electronic throttle actuation,
• on-board diagnostics,
• the engine cooling fans, and
• the A/C compressor clutch (where fitted).
Figure 6C4-1 – 36
The ECM supplies 5 volts to the various sensors through pull-up resistors to the internal regulated power supplies.
The ECM controls output circuits such as the injectors, IAC, cooling fan relays, etc. b y controlling the ground circuits
through transistors or a device inside the ECM called a driver.
The exception to this is the fuel pump relay control circuit. The fuel pump relay is the only ECM controlled circuit where
the ECM controls the +12 volts sent to the coil of the relay. The ground side of the fuel pump relay coil is connected to
engine ground.
The ECM also interfaces with other systems in the vehic le, s uch as body control module (through the PI M), anti-lock
braking, traction control, etc.
Self Diagnosis
The ECM performs diagnostic tests on system components and constantly monitors the system for faults .
When the ECM detects a malfunction, it also stores a diagnostic trouble code (DTC). A stored DTC will identify the
problem area(s) and is desig ned to assist the technician in rectifying the fault.
Depending on the type of DTC set, the ECM may command the instrument cluster multi-function displ ay Check Engine
icon to illuminate and warn the driver that there is a fault in the powertrain management system. Communication to the
Icon is through the controller area network (CAN) serial data communication line to the powertrain interface module
(PIM), and then universal asynchronous receive and transmit (UART) serial data to the instrument cluster via the body
control module (BCM). For further information on DTCs and the check powertrain icon,
refer to Section 6C4-2 Engine Management – GEN IV V8 – Diagnostics.
Programming
The ECM features electronically erasable programmable read only memory (EEPROM) which contains program and
calibration information required to operate the powertrain mana gement system. The service programming system (SPS)
has been incorporated with this ECM and enables a technician to directly update th e data stored in the EEPROM. In
effect, the data in the memory matches the ECM to the vehicle to provide optimum performance, driveability and
emissions control.
Flash programming refers to the SPS used to transfer (or download) ECM data from a computer terminal and compact
disc-read only memory (CD-ROM) to the vehicle’s ECM. The system is designed so that the vehicle verification
procedures are required to eliminate EEPROM tampering that could increa s e engine emission levels.
Engine Management GEN IV V8 – General Information Page 6C4-1–39
Page 6C4-1–39
There are three main flash pr ogramming techniques:
1 Direct programming (Pass Through). This is where the vehicle’s data link connector (DLC) is connected directly to
a computer terminal. On screen directions are then followed for downloading.
2 Remote programming. Reprogramming information is downloaded from a computer terminal to TECH 2. TECH 2 is
then connected to the vehicle’s data link connector (DLC). On screen directions are then followed for downloading.
3 Off-board Programming. The off-board programming method is used when a re-programmable ECM must be
programmed while it is removed from the vehicle. For example, an independent repair facility ma y find it necessary
to replace a faulty ECM. On flash programming eq uipped vehicles, the replacement ECM must be programmed
with data for the specific vehicle identification number (VIN) or the vehicle may not operate properly.
The vehicle is fitted with a theft deterrent system that interfaces with the ECM. If the ECM is replaced it must be
programmed with appropriate data to match the theft deterrent system.
For further information on the SPS, refer to Section 0C TECH 2.
Engine Management GEN IV V8 – General Information Page 6C4-1–40
Page 6C4-1–40
4.18 Vehicle Speed Sensor (VSS)
The ECM receives vehicle speed i nformatio n from the
vehicle speed sensor (VSS) located on the rear of the
transmission (1).
Figure 6C4-1 – 37
The VSS consists of a magnetic core and a coil. Mounted
on the transmission output shaft is a toothed rotor which
revolves past the VSS, causing fluctuations in the magnetic
field inside the sensor. The magn etic flux increases and
then decreases as the teeth move in and out of the
magnetic field, inducing an AC voltage i nto th e coil. An
increase in speed will increase the output voltage and
frequency.
This AC voltage produced in the VSS sensor circuit is fed
into the ECM. The ECM measures the AC voltage and
frequency to determine the vehicle speed. T he ECM also
sends this information to the instrument cluster.
Legend
1 Sensor Body
2 Electrical Connector
3 Magnetic Pickup
4 Reluctor Wheel (Rotor)
5 O-Ring Figure 6C4-1 – 38
Engine Management GEN IV V8 – General Information Page 6C4-1–41
Page 6C4-1–41
5 Abbreviations and Glossary of
Terms
Abbreviations and terms used in this Section are listed below in alphabetical order with an explanation of the
abbreviation or term.
Abbreviation Description
A/C Air-conditioning
AC Alternating Current – An electrical current where the polarity is constantly changin g between
positive and negative
A/F Air / Fuel (A/F Ratio)
Adaptive Learning Adaptive learning is the ability of the ECM to learn the particular characteristics of the system that
it controls, using features such as LTFT.
Analogue Signal An electrical signal that const antly varies in voltage within a given par ameter
Barometric
Pressure Barometric absolute pressure (atmospheric pressure)
CAN Controller Area Network – A type of serial data for communication between electronic devices.
Catalytic Converter A muffler-shaped device fitted in the exhaust system, usually close to the engine. Through
chemical reaction, a catalytic converter converts harmful gases produced by the combustion
process such as HC, CO, and NOx, into environme ntall y safe water vapour, carbon dioxid e, and
nitrogen.
CKT Circuit
Closed Loop A fuel control mode of operation that us es the signal from the exhaust oxygen sensor(s), to control
the air / fuel ratio precisely at a 14.7 to 1 ratio. This allows maximum efficiency of the cat alytic
converter.
CO Carbon Monoxide. One of the gases produced by the engine combustion process.
DC Direct Current
Digital Signal An electrical signal that is either on or off.
DLC Data Link Connector. Used at the assembly plant to evaluate the powertrain management system.
For service, it allows the use of TECH 2 in performing system checks.
DLC Data Stream An output from the ECM initiated by TECH 2 and transmitted via the Data Link Connector (DLC).
DMM (10 MΩ) Digital Multimeter. A multipurpose meter that has capability of measuring voltage, current flow and
resistance. A digital multimeter has an input impedance of 10MΩ, which means they draw very
little power from the device under test, they are very accurate and will not damage delicat e
electronic components
Driver An electronic device, usually a power transistor that operates as an electrical switch.
DTC Diagnostic Trouble Code. If a fault occurs in the po wertrain manageme nt system, the ECM may
set a four digit diagnostic trouble code (DTC) which represents the fault condition. T ECH 2 is
used to interface with the ECM and access the DTC(s). The ECM may also operate the check
powertrain icon in the instrument cluster multi- function display.
Duty Cycle The time, in percentage, that a circuit is on versus off .
ECT Sensor Engine Coolant Temperature sensor. A device that provides a variable voltage to the ECM based
on the temperature of the engine coo lant.
ECM Engine Control Module. An el ectronic device which controls the powertrain management system.
EEPROM Electrically Erasable Programmabl e Read Only Memory . A type of read only memory (ROM) that
can be electrically programm ed, erased and reprogrammed using TECH 2. Also referred to as
Flash Memory
EMI or Electrical
Noise An unwanted signal interfering with a required signal. A common example is the effect of high
voltage power lines on an AM radi o.
Engine Braking A condition where the engi ne is used to slow the vehicle on closed throttle or low gear.
EPROM Erasable Programmable Read Only Memory. A type of Read Only Memory (ROM) that can be
erased with ultraviolet light and then reprogrammed.
ESD Electrostatic Discharge. The discharge of static electricity which has built up on an insulated
material
Engine Management GEN IV V8 – General Information Page 6C4-1–42
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Abbreviation Description
EVAP Evaporative emission control system. Used to prevent fuel vapours from the fuel tank from
entering into the atmosphere. The vapours are stored in a canister that contains an activated
charcoal element. The fuel vapours are purged from the canister into the manifold to be burned in
the engine.
GM LAN General Motors Local Area Network – A type of serial data for communication b etween electronic
devices.
Fuse A thin metal strip which melts when excessive current flo ws through it, creating an open circuit
and protecting a circuit from damage.
HC Hydrocarbon. Result of unburned fuel produced by incomplete combustion.
Heated O2 Sensor Heated Oxygen Sensor. A device located in the exhaust system that provides a variable voltage to
the ECM based on the oxygen content of exhaust gas
Heavy Throttle Approximately 3/4 of accelera tor pedal travel (75% throttle position)
IAT Sensor Intake Air Temperature senso r . A device that provides a variable voltage to the ECM based on the
temperature of air entering the intake system.
Ideal Mixture The air / fuel ratio which provides the best performance, while maintaining maximum conversion of
exhaust emissions, typically 14.7 to 1 on spa rk ignition engines
IGN Ignition
Inputs Information from sensors (MAF, TP, etc.) and switches (A/ C request, etc.) used by the ECM to
determine how to control its outputs.
Intermittent An electrical signal that occurs no w and then; not continuously. In electrical circuits, refers to
occasional open, short, or ground in a circuit
Light Throttle Approximately 1/4 of accelerator peda l travel (25% throttle position)
Low A voltage less than a specific threshold. Operates the same as a ground and may, or may not, be
connected to chassis ground.
MAF Sensor Mass Air Flow Sensor. A device that provides a variable voltage to the ECM based on the amount
of air flow entering in the intake system.
MIL Malfunction Indicator Lamp, located in the instrument cluster, will illuminate if the engine starts
operating outside the pre-programmed emission parameters
Medium Throttle Approximately 1/2 of accelerator pedal travel (50% throttle position)
N.C Normally Closed. Switch contacts that are closed when they are in the n ormal operating position
N.O Normally Open. Switch contacts that are normally open when in the normal operating position
NOx Nitrogen Oxide. One of the pollutants found in spark ig nition engine exhaust that is formed from
normal combustion and increases in severity with combustion temperature.
O2 Sensor Oxygen Sensor. A device loc ated in th e exhaust system that provides a variable voltage to the
ECM based on the oxygen content of exhaust gas.
May also include a heating circuit to provide faster initial warm-up (Heated O2 sensor).
OBD On Board Diagnostic
Open Loop ECM control of the fuel control system without the use of the oxygen sensor signal.
Output Functions that are controlled by the ECM, typically these can include solenoids and relays, etc.
PCV Positive Crankcase Ventilation. Method of re burning crankcase fumes rather than passing them
directly into the atmosphere
PIM Powertrain Interface Module – The PIM acts as a communication trans lator between the ECM and
other on-board controllers tha t use a different serial data protocol.
PM Permanent Magnet
PWM Pulse Width Modulated. A digital signal turned on and off for a percentage of availabl e cycle time.
A signal that is 30% on and 70% off would be termed a 30% on PWM signal.
Quad Driver A transistor in the ECM capable of operating four separate o utputs. Outputs can be either on-off or
pulse width modulated.
RAM Random Access Memory. A microprocessor c an write into or read from this memory as needed.
This memory is volatile and needs a constant power supply to be retained. If the power is lost or
removed, RAM data is lost.
RPM Revolutions Per Minute
Serial Data Serial data is a series of rapidly changing voltage signals pul s ed from high to low. These signals
are typically 5 volts (UART), 7 volts (Class II), and 12 or 0 volts (high or low) and are transmitted
through a wire often referred to as the Serial Data Circuit.
Engine Management GEN IV V8 – General Information Page 6C4-1–43
Page 6C4-1–43
Abbreviation Description
SFI Sequential Fuel Injection. Method of injecting fuel into the engine one cylinder at a time in relation
to the engine’s firing order.
Solenoid An electromagnetic coil which creates a magnetic field when current is applied, causing a plu ng er
or ball to move.
Switch Device to opens and close a circuit, thereby controlling current flow.
TECH 2 TECH 2 is a peripheral device that aids in th e diagnosis and repair of electronic systems such as
powertrain management, ABS, etc. TECH 2 connects to the vehicle’s Data Link Connector (DLC).
TP Sensor Throttle Position sensor. A device that provides a variable voltage to the ECM based on the
position of the throttle plate.
Vacuum – manifold Vacuum sourced downstream of the throttle plate.
Vacuum – ported Vacuum sourced upstream of the throttle plate.
VSS Vehicle Speed Sensor. A permanent magnet type device that provides a digital voltage to the
ECM.
UART Universal Asynchronous Receive and Transmit. A type of serial data for communication between
electronic devices.
WOT Wide Open Throttle – Full travel of the accelerator pedal (100% throttle position).