+15/+30 Supply to Fuel Pump Relay

Fault diagnosis, +15/+30 supply to fuel pump relay

Fault symptom
Fuel pump relay not working


Important : In 4-cyl cars, the fuel pump relay is supplied with +15, and in 6-cyl cars, the fuel pump relay is supplied with +30.


Action
1 Check the fuel pump relay voltage supply
Unplug the fuel pump relay.
Connect the test lamp between the relay holder, pin 86 and a safe grounding point.
The alarm should be disarmed.
Ignition at "ON" (+15).
The test lamp should light.
If the test lamp lights, continue fault diagnosis in "Engine control", Trionic (4-cyl cars) or Motronic (6-cyl cars). Testing and Inspection
If the test lamp does not light, proceed to point 2.
2 Check +15/+30 supply to the control module
Remove the theft alarm control module.
Connect the test lamp between pin 21 in the control module connector and a safe grounding point
Ignition at "ON" (+15).
The test lamp should light.
If the lamp lights, proceed to point 4.
If not, proceed to point 3.
3 Check the cable assembly
Conduct a continuity test and remedy the cable assembly between the control module connector, pin 21 and:
- main relay, pin 87 (6-cyl)
- fuse 13 (4-cyl)
The resistance should be <1 Ohm.







4 Chock the function of the electronic control module
Connect jumper between pin 21 and pin 9 in the control module connector.
Unplug the fuel pump relay.
Connect the test lamp to connector pin 86 and a safe grounding point
Ignition at "ON" (+15).
The test lamp should light.
If the lamp lights, proceed to point 6.
If not, proceed to point 5.
5 Chock the cable assembly
Conduct a continuity test and remedy the cable assembly between the control module connector, pin 9 and the fuel pump relay, pin 86.
The resistance should be <1 Ohm.
6 Final test
Start the car and check to see if the fault symptom remains.
If the problem remains, proceed to "Before Changing the Electronic Control Module". Before Changing the Electronic Control Module