Checking Wiring and Terminals. Permanent Fault

Checking wiring and terminals. Permanent fault

Check terminals visually





Note! When checking the engine control module (ECM), do not remove the control module from the car before the main relay has interrupted the power supply. This may take up to 4 minutes after the ignition has been switched off and the engine cooling fan (FC) has stopped running.

Inspect the terminals visually when checking, or taking readings from, opened connectors.
For repair of wiring and terminals, reference the relevant wiring diagram(s).

Checks:
- Check for oxidation. This can cause poor connections in the terminals
- Check for damage to pins and terminals. Check that they are properly inserted into the connector. Check that the cable is properly connected to the pin or terminal. Check pins and terminals particularly carefully
- Use a separate male terminal to check the female terminal. Check that they are secure: Pull on the pin.

Open-circuit, permanent faults




An open-circuit in a cable is indicated by a loss of one or more functions.
Chafed and broken cables or terminals that have come loose are common causes of faults in electrical systems.
For repair of wiring and terminals, reference the relevant wiring diagram(s).

Checks:
- Disconnect the connectors at both ends of the cable.
Connect an ohmmeter between the ends of the cable.
The ohmmeter should read approximately 0 ohms if there is no open-circuit in the cable.




Always check the control module and control module box connectors to ensure that their pins and sockets are not bent or damaged, as this can cause faults.
Check pins and terminals particularly for this fault. See Check terminals visually.

Short-circuit to ground, permanent faults




A short-circuit between a live cable and ground is often indicated by the loss of a function or a fuse blowing when a current is passed through the cable.
For repair of wiring and terminals, reference the relevant wiring diagram(s).

Checks:
- Activate all switches and sensors in the circuit. Check whether the fuse blows
- Disconnect the connectors in the circuit to ensure that they do not affect readings.
Use an ohmmeter to take a resistance reading between the cable and ground.
The ohmmeter should read infinite resistance if no components are connected.
Check pins and terminals particularly for this fault. See Check terminals visually.

Short-circuit to supply voltage. Permanent faults




A short-circuit between a cable and supply voltage is often indicated by the loss of a function or a fuse blowing when voltage is passed through the cable.
For repair of wiring and terminals, reference the relevant wiring diagram(s).

Checks:
- Use a voltmeter to take readings at various points in the circuit while operating switches and sensors.
Voltmeter readings will depend on which circuit is tested and the status of switches and sensors. Use the wiring diagram to determine the correct voltage in the circuit.
Use an ohmmeter between the suspect cables to detect short-circuits between them.
The ohmmeter should read infinite resistance between cables not connected to each other in the circuit.
Check pins and terminals particularly for this fault. See Check terminals visually.

Contact resistance and oxidation




For repair of wiring and terminals, reference the relevant wiring diagram(s).
In theory, the resistance across contacts, leads and terminals should be 0 ohms. However, there is always some resistance due to terminal oxidation.
If this resistance becomes too great the result will be a malfunction. The magnitude of the resistance before it causes a malfunction depends on the circuit load.

Checks:
- Check the cables visually according to Check terminals visually.

Cleaning female socket terminals and male pin terminals





Note! Do not apply rust solvent spray or grease to the catalyst monitor sensor or instrument cluster connectors.

- Ignition off
- Disconnect the battery negative terminal
- Use compressed air to clean the disconnected connector
- Apply rust solvent spray 1161422 to the disconnected connectors
- Blow clean using compressed air.

Greasing female terminals





Note! Note! Do not fill the protective cover with grease.

- Press grease, P/N 1161417-9, into the female sockets directly from tube
- Check that all the terminal cavities are filled
- Use a loose male pin to ensure that the connection in the sockets is good. The pin should remain in position when pulled gently.