Checking Wiring and Terminals
Checking Wiring and Terminals, Permanent Faults
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.
To repair wiring and cable terminals.
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.
- To repair wiring and cable terminals.
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 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.
To repair wiring and cable terminals.
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.
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.
To repair wiring and cable terminals.
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
To repair wiring and cable terminals.
In theory, the resistance across contacts, leads and terminals should be "0". 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 heated oxygen sensor (HO2S) or combined instrument panel 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: 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.
Checking Wiring and Terminals, Intermittent Faults
Inspect 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.
To repair wiring and cable terminals.
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
- Using a loose male connector, test to see if the female connector provides a good contact and that the pin remains in place when the male connector is pulled lightly
- Shake the cable lightly and pull on connectors during measurement to locate damage.
Open circuit, intermittent faults
An open-circuit in a cable will be indicated by the loss of a function (or functions).
Chafed and broken leads are common causes of faults.
To repair wiring and cable terminals.
Checks:
- Disconnect the connectors at both ends of the cable.
- Check the cables visually according to Inspect terminals visually
- Connect an ohmmeter between the ends of the cable.
- The ohmmeter should read approximately 0" if there is no open circuit in the cable.
- Shake the cable lightly and pull on connectors during measurement to locate the damage.
- If the reading is not correct. Replace the cable and/or continue according to Contact resistance and oxidation.
- Always check the control module and control module box connectors to ensure that their pins and sockets are not bent or damaged, this may cause faults.
- Check pins and terminals particularly carefully.
Short circuit to ground, intermittent 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.
To repair wiring and cable terminals.
Checks:
- Check the cables visually according to Inspect terminals visually.
- 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.
- Connect an ohmmeter between cable and ground.
- The ohmmeter should read infinite resistance if no components are connected.
- Shake the cable lightly and pull on connectors during measurement to locate the damage.
- If the value is not correct, try a new cable and/or continue according to Contact resistance and oxidation
Short circuit to supply voltage, intermittent faults
A short-circuit between a cable and supply voltage is often indicated by the loss of a function or a fuse blowing when a current is passed through the cable.
To repair wiring and cable terminals.
Checks:
- Check the cables visually according to Inspect terminals visually.
- Use a voltmeter to take readings at various points in the circuit while operating switches and sensors.
- The voltmeter reading depends on the circuit being tested and the positions 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.
- Shake the cable lightly and pull on connectors during measurement to locate the damage.
- If the reading is not correct. Replace the cable and / or continue according to Contact resistance and oxidation.
Loose connections (terminals)
To repair wiring and cable terminals.
Loose connections in terminals may be caused by oxidation of the pins and sockets, or by a faulty connection of a cable to its cable terminal.
Loose connections produce the same faults as an intermittent open circuit in a cable.
Checks:
- Inspect terminals visually according to Inspect terminals visually.
- Continue according to Contact resistance and oxidation.
Contact resistance and oxidation
In theory, the resistance across contacts, leads and terminals should be "0". However, there is always some resistance due to terminal oxidation.
If resistance is too great there will be function problems. The magnitude of the resistance before it causes a malfunction depends on the circuit load. A guideline would be a few ohms.
Cleaning female socket terminals and male pin terminals
NOTE: Do not apply rust solvent spray or grease to the heated oxygen sensor (HO2S) or combined instrument panel 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: Do not fill the protective cover with grease.
- Press grease, P/N 1161417-9, into the terminals directly from the tube
- Check that all the cavities in the connectors are filled
- Use a loose male pin to ensure that contact in sockets is good. The pin should remain in position when pulled gently.