
CHECKING TERMINAL CONTACT
Before replacing a suspect faulty component, it is important to check terminal contact between a connector and the
component, or between in-line mating connectors.
Frequently, a diagnostic chart leads to a step that reads for example ‘Check for poor connection’. Mating terminals
must be inspected to ensure good terminal contact. A poor connection between the male and female terminals at a
connector may be the result of contamination or deformation.
Contamination is caused by the connector bodies being improperly connected, a missing or damaged connector
seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in the
engine compartment or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently
open circuit.
Deformation is caused by probing the mating side of a connector terminal without the proper adaptor, improperly
joining the connector bodies or repeatedly separating and reconnecting the connector bodies together. Deformation,
usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently
open circuit.
To check terminal contact:
1. Separate the connector bodies or connector for a component.
2. Inspect the connector bodies or component for contamination. Contamination will result in a white or green
build-up within the connector body or between the terminals, causing high resistance, intermittent contact, or
an open circuit. An engine compartment or underbody connector that shows signs of contamination should
either be replaced if it is serviced (refer to VT Parts information for connectors that are serviced) or replace the
relevant wiring harness.
3. Using an equivalent male terminal, check the retention force of the female terminal in question by inserting and
removing the male terminal to the female terminal in the connector body. Good terminal contact will require a
certain amount of force to separate the terminals.
4. Using a known good condition equivalent female terminal, compare the retention force of this terminal to the
female terminal in question by inserting and removing the male terminal. If the retention force is significantly
different between the two female terminals, replace the female terminal in question.
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a
DMM connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the
problem may be in that circuit.
METER CONNECTIONS
The procedure for detecting intermittents was based on the digital multimeter set to read voltage. Whether using
current, voltage or resistance settings to detect intermittents, it will be necessary to connect the meter into the
circuit.
The following are examples of various methods of connecting the meter into a circuit to be checked.
1. Backprobe both ends of the connector and either hold meter leads in place while manipulating the connector
or, tape leads to the harness for continuous monitoring while performing other operations or while test driving.
IMPORTANT:
DO NOT BACKPROBE 'WEATHER PACK' TYPE CONNECTORS AS DAMAGE TO THE CABLE SEALS WILL
RESULT.
2. Disconnect the harness at both ends of a suspect circuit where it connects either to a component or to other
harnesses.
Use connector test adaptor kit, Tool No. J35616-A or KM-609 to connect meter onto the circuit.
Additional Information
NOTE:
Turn off power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or
damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests
that work well for detecting intermittent shorts to earth can be performed by setting the meter to ohms when
pressing the PEAK MIN MAX button. An audible tone will be heard whenever the meter detects continuity for at
least 1 millisecond.
Quite often the instruction manual accompanying the multimeter is a good source of information and should be read
thoroughly before using the meter as well as kept on hand for reference during new procedures.