WWA. Checking Cables and Terminals. Permanent Faults

WWA1. Visual Inspection Of Connections







NOTE: When checking the Motronic 4.3 control module, do not remove it from the car until the main relay has cut the voltage supply. This may take up to 150 seconds after the ignition has been switched off.


If connectors are opened for measurements and checks the terminals should always be inspected visually. Look for oxidation which may cause poor contact in terminals

Check that pins and terminals are undamaged, that they are properly inserted into the connector and that the conductor is properly connected to the pin/terminal. In particular check pins and terminals for the relevant fault.

Test with a spare male pin that the female socket is making a good connection. Also check that they are securely fastened by pulling on the terminal pins.


WWA2. Open-circuit






An open-circuit in a cable will be indicated by the loss of one or more functions. Chafed or broken cables or terminals that have come loose are all common causes of faults in electrical systems.





Disconnect connectors at both ends of the cable. Connect an ohmmeter between the ends of the cable. The ohmmeter should read approx. 0 Ohms if the cable is intact.

Always check control module and control module box connectors to ensure that their pins and sockets are not bent or damaged, this may cause faults. In particular check pins and terminals for the relevant fault, according to WWA1.



WWA3. Short-circuit to ground





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.





Activate all switches and sensors in the circuit and check to see if the fuse blows. Disconnect connectors in the circuit to ensure that they do not affect readings.

Use ohmmeter to measure resistance between lead and ground. The ohmmeter should read infinite resistance if no components are connected. In particular check pins and terminals for the relevant fault, according to WWA1.



WWA4. Short-Circuit To Supply Voltage





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.






Use a voltmeter to take readings at various points of the circuit while operating switches and sensors. Voltmeter readings will depend on the circuit and status of switches and sensors. Use the wiring diagram to determine the correct voltage in the circuit.

Use an ohmmeter between suspect cables to detect short-circuits between them. The ohmmeter should read infinite resistance between leads not connected to each other in the circuit. In particular check pins and terminals for the relevant fault, according to WWA1.


WWA5 Contact resistance and oxidation






The resistance in contacts, cables and terminals should be 0 Ohms. However, a certain degree of resistance will be present due to oxidation of the connections.

If this resistance becomes too great the result will be a malfunction. The magnitude of resistance before it causes a malfunction depends on circuit load.




Check cables visually in accordance with WWA1.


NOTE: Do not use spray or grease on heated oxygen sensor (HO2S) or combined instrument panel connectors.


Cleaning female socket terminals and male pin terminals
Ignition off
Disconnect battery negative lead
Use compressed air to clean the disconnected connector.
Spray rust solvent spray 1161422 on the disconnected connectors.


Greasing terminals





NOTE: Do not fill the protective cover with grease.

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