Omega B
Function:
On ignition "ON", both relays 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 telltale illuminates and a trouble code is stored in the control unit:
- Trouble code 53: fuel pump relay voltage too low. - Trouble code 54: fuel pump relay voltage too high.
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.
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