Fuel Pump/Injection System Relay
Function:
With the ignition on, both parts of the relay are actuated by the Motronic M 1.5.4. While the injection system relay remains actuated and thus guarantees the control unit functions for, e.g. the self-diagnosis, the fuel pump relay switches off after approx. 2 seconds. The fuel pump relay is only actuated to allow the fuel pump to run when the Motronic control unit receives engine speed signals from the crankshaft pulse pick-up.
· Service
If the fuel pump relay or the actuation lead between the fuel pump relay and the control unit is defective, the engine control indicator illuminates and a trouble code is stored in the control unit.
The injection system relay cannot be monitored by the Motronic M 1.5.4 as a defective injection system relay is evaluated by the Motronic M 1.5.4 as meaning "ignition off". A defect can be detected when the ignition is on and the self-diagnosis does not function.