P1501

P1501
Fuel Pump Relay Circuit - Short to Ground
End-stage Fuel Pump Relay - below lower limit.

P1502
Fuel Pump Relay Circuit - Short to B +
End-stage Fuel Pump Relay - upper limit exceeded

P1541
Fuel Pump Relay Circuit - Open
End-stage Fuel Pump Relay - interruption

Function
To prevent the fuel pump from running with ignition on and engine not running, a safety switch is integrated in the ECM. Beginning with engine speed of 25 1/min, the ECM supplies a ground connection to the ECM relay.

Diagnostic conditions
Short circuit to B+: A fault is recognized and stored in memory when the engine speed is higher than 80 1/min and the battery voltage is between 7.5 Volt and 17 Volt.

Short circuit to ground and interruption: A fault is recognized and stored in memory only in the after-run of the ECM program, meaning, when the ignition is switched off after the engine has run.

NOTE: The signal wiring for the ECM relay is monitored via terminal 85.





Wiring Diagram.

Diagnostic procedure.




DTC P1501.




DTC P1502.




DTC P1541.

Check ECM relay.
1. Remove ECM relay.
2. Connect ohmmeter to terminal 85 (minus) and terminal 86 (plus).

- Specified value: approximately 1200 kohms.

NOTE: A diode is connected in series with the coil, therefore watch polarity.

Check wiring from ECM to ECM relay for short circuit to ground
1. Remove ECM relay.
2. Remove connector X 4/1.
3. Connect ohmmeter to ECM relay connector, pin 6 and to ground.

- Specified value: infinite resistance
- If meter reads 0 - 5 ohms, check wiring harness for chafing and pinching damage.

4. Remove ECM connector.
5. Connect ohmmeter to connector X 4/1, pin 4 on pin side and ground.

- Specified value: infinite resistance
- If meter reads 0 - 5 ohms, check wiring harness for chafing and pinching damage.

Check wiring from ECM to ECM relay for short circuit to B+.
1. Remove ECM relay.
2. Remove connector X 4/1.
3. Switch ignition on.
4. Connect voltmeter to ECM relay connector on relay panel, pin 6 and ground.

- Specified value: 0 Volt
- If meter reads battery voltage, check wiring harness for chafing and pinching damage.

5. Remove ECM connector.
6. Connect ohmmeter to connector X 4/1, pin 4 on pin side and ground.

- Specified value: 0 Volt
- If meter reads battery voltage, check wiring harness for chafing and pinching damage.

Check wiring from ECM to ECM relay for continuity.
1. Remove ECM relay.
2. Remove ECM connector.
3. Connect ohmmeter to connector for ECM relay on relay panel, pin 6 and ECM connector, pin 27.

- Specified value: 0 - 5 ohms
- If meter reads infinite resistance, check connector X 4/1, pin 4.