Checking Cabling and Connections

Important Information About SRS Cabling

WARNING: These instructions should be followed carefully for the SRS system. If there is a diagnostic trouble code (DTC) posted follow procedures in C. If there are fault symptoms but no diagnostic trouble code (DTC) follow procedures for: Symptom Related Diagnostic Procedures

CAUTION: SRS cabling must not be repaired or spliced and individual cables may not be replaced. If there is a fault in the cabling the SRS ignition cable and/or cable harness must be replaced.

General
Many faults in the electrical system are due to defective cabling and poor connections.
These faults most often occur because of interference from other electrical systems and mechanical or chemical damage.

Check Terminals Visually
Whenever connectors are disconnected for readings or checks to be made, terminals should be checked visually.

Checks:




- Look for oxidation which could affect contact in the connectors.
- Ensure that terminal pins are undamaged and that copper conductor is properly connected to the pin.

Open Circuit




An open-circuit is indicated by the loss of a function. Worn cabling and loose terminals are common causes of faults.

Checks:
- Disconnect the connectors at both ends of the cabling.
- Measure the resistance between the ends of the cabling using an ohmmeter.
The ohmmeter should read 0 Ohms in cabling without an open-circuit.

Checking for intermittent open-circuits:
- Check cabling visually in accordance with DC1.
- Gently shake the cabling and pull the connectors to find out where the cabling is damaged.

Short-circuit To Ground
Short-circuits between live cabling and ground generally blow the fuse when a current passes through the cable or are indicated by the loss of a function.

Checks:








- Activate all switches and sensors in the circuit and check to see if the fuse blows.
- Disconnect circuit component connectors so that these do not affect readings.
- Measure the resistance between the cable and ground using an ohmmeter.
The ohmmeter should read infinite resistance when no components are connected.

Checking intermittent short-circuits to ground:
- Check cabling visually in accordance with DC1.
- Gently shake the cabling and pull the connectors to find out where the cabling is damaged.

Short-circuit To Supply Voltage




Short-circuits between live cabling and supply voltage generally blow the fuse when a current passes through the cable or are indicated by the loss of a function.

Checks:




- Use a voltmeter to take readings at different points of the circuit while activating switches and sensors.
The voltmeter reading depends on the circuit and the status of switches and sensors. Use the wiring diagram to find the correct voltage in the circuit.

- Use an ohmmeter to take readings between suspected cables to locate short-circuits.
The ohmmeter should read infinite resistance between cables which are not connected to each other in the circuit.

Checking intermiffent short-circuit to supply voltage:
- Check cabling visually in accordance with DC1.
- Gently shake the cabling and pull the connectors to find out where the cabling is damaged.

Loose Contact (In Connectors)




Loose contact in connectors is caused by the oxidation of pins and contacts or by poorly connected cabling.
Loose contacts give the same faults as intermittent open-circuits in cabling.

Checks:




- Check connectors visually in accordance with DC1.
- Gently shake the cabling and pull the connectors to find out where the cabling is damaged.

- Always check the control module and control module box connector for bent or damaged pins or sockets.

CAUTION: When checking the control module do not remove it from the car before the main relay is no longer live. This can take up to 90 seconds after the ignition has been switched off.

Contact Resistance And Oxidation
The resistance of contacts, cabling and terminals should strictly speaking be 0 Ohms. However there will always be some resistance due to the oxidation of terminals.
If resistance becomes too great, functions will be interrupted. The point at which this resistance will cause interference varies with the load on the circuit.
A guideline is a few ohm.

Checks:




- Check connectors visually in accordance with DC1.

CAUTION: When checking the control module do not remove it from the car before the main relay is no longer live. This can take up to 90 seconds after the ignition has been switched off.

Cleaning Pins And Sockets

CAUTION: Do not use rust solvent spray or grease on SRS ignition cable or SRS sensor module connectors. Do not use rust solvent spray or grease on heated oxygen sensor (HO2S) or combination instrument connectors.




- Ignition off.
- Disconnect the battery negative terminal.
- Spray rust solvent spray, P/N 116 1422-9, on the disconnected connector.
- Blow clean using compressed air.

Greasing Female Contacts

CAUTION: Do not fill the protective sleeve with grease.








- Press grease 116 1417-9 into female contacts direct from the tube.
- Check that cavities are filled in all female sockets.
- 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.