DI/APC
Main relayDiagnostic procedure
1 Check the power supply
- Ignition switch in ON position.
- Check the power supply in connector 123/H4-10, pin 4 (grey/red), or pin 10 in the ignition discharge module.
Is battery voltage present?
YES Continue with point 2.
NO Continue with point 3.
2 Checking the voltage
- Run the starter motor.
- Check the power supply in connector 123/H4-10, pin 4, or in the ignition discharge module, pin 10.
A reading of at least 10 V should be obtained.
Is the correct voltage obtained?
YES The relay and leads are OK.
NO Continue with point 3. The fault is probably due to burnt contacts in the relay.
3 Check the power supply
Check the power supplied to:
- Distribution block 75.
- Distribution terminal 230. Check that the screw is tightened down hard.
Is battery voltage present?
YES Continue with point 4.
NO Check the leads and repair or replace them as necessary.
4 Check the power supply
- Check the power supplied to relay pins 30 and 86.
Is battery voltage present?
YES Continue with point 5.
NO Rectify the fault.
5 Check the power supply
- Check the power supplied to relay pin 30 when the starter motor is cranking the engine.
- Check the power supplied to pin 87b.
Is the voltage lower on pin 87b?
YES Change the relay. Its contacts are probably burnt.
NO Continue with point 6.
6 Check the power supply
- Ignition switch in the OFF position.
- Check the power supplied to relay pin 85.
Is battery voltage present?
YES Continue with point 7.
NO Change the relay.
7 Check the power supplied to the relay
- Ignition switch in ON position.
- Check the power supplied to relay pin 85. It should be about 1 V.
Is battery voltage present?
YES Continue with point 8.
NO Continue fault diagnosis of the LH system. LH System Diagnostics
8 Check the power supplied connectors
- Check the power supplied to the following connectors:
- Connector 98, pin 2, or connector H10-7, pin 2 (grey/red).
- Connector 123/H4-1 0, pin 4 (grey/red), or the ignition discharge module, pin 10.
Is the correct voltage obtained?
YES OK.
NO Check and if necessary repair or replace the leads between the various points. Inspect crimped connection J76 (from M92, inclusive) for an open circuit. Check and if necessary rectify the fixing of the pins and sockets. They should be fixed so that slid-out does not occur when the connectors are plugged in.