1 Check fuel pump relay.
1. Remove fuel pump relay.
2. Connect ohmmeter to terminals 85 and 86.
Display: approx. 75 ohms
2 Check wiring from DME control module, pin IV/10, to fuel pump relay for short circuit to ground.
1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Remove fuel pump relay.
3. Connect ohmmeter to special tool 9637, pin IV/10, and ground.
Display: infinity ohms
If 0 - 5 ohms is displayed, check wiring harness for chafing and pinching damage.
3 Perform adaptation.
1. Switch on the ignition.
2. Wait one minute.
Do not press the accelerator.
3. Switch off the ignition for at least 10 seconds.
4. Read out the fault memory.
4 Check wiring from DME control module, pin IV/10, to fuel pump relay for short circuit to B+.
1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Remove fuel pump relay.
3. Connect voltmeter to special tool 9637, pin IV/10, and ground.
Ignition on.
Display: 0 V
5 Check wiring from DME control module, pin IV/10, to fuel pump relay for continuity.
1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Remove fuel pump relay.
3. Connect ohmmeter to special tool 9637, pin IV/10, and fuel pump relay slot, pin 6 (terminal 85).
Display: 0 - 5 ohms
If infinity ohms is displayed, check connector X 2/3, pin 23, and check wiring harness for chafing and pinching damage.
Fuel Pump Relay Output Stage - Below Limit
P1124
Fuel Pump Relay Output Stage - Below Limit
Function
A protective circuit is integrated in the DME control module to prevent the fuel pump from running when the engine is off and the ignition is on. The
DME control module transmits a ground signal to the fuel pump relay from an engine speed of 25 rpm.