Fuel Pump Relay

TEST PROCEDURE
Function Check
The Fuel Pump Relay (EKP) switches on as soon as the Digital Motor Electronic (DME) control unit outputs a ground signal at Pin 1 with overlaid engine speed signal (once per crankshaft revolution). In addition, at ignition "ON", the EKP relay is briefly activated by the DME in order to build up the necessary fuel pressure before starting.

Possible Causes For Incorrect Response:
- Wire to DME control unit Pin 1 defective
- Relay 1 or voltage supply not OK
- Voltage supply for DME control unit not OK
- No signal from engine crankshaft sensor (speed/position pulse generator)
- The control unit is defective if ground potential is not output at Digital Motor Electronic (DME) control unit Pin 1 during start and engine operation although the above points are OK.