P0629

P0629-HIGH VOLTAGE DETECTED AT THE FUEL LIFT PUMP





For complete wiring diagrams refer to Diagrams/Electrical.


- When Monitored:

While the key is on.

- Set Condition:

The commanded signal to the fuel lift pump relay does not match the feedback signal from the fuel lift pump relay .







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test


1. LIFT PUMP DRIVER CIRCUIT SHORTED TO GROUND





Disconnect the ECM and TIPM connectors.


NOTE: Check connectors - Clean/repair as necessary.

Using an ohmmeter, measure the resistance of the lift pump driver wire between the ECM connector and ground.

Is the resistance less than 10 Ohms?

Yes

- Fix or repair the wire harness.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 2

2. ECM





Turn Ignition off.

Connect the ECM and TIPM connectors.

Turn the ignition on, engine off.

Using a back probing tool 6801, back probe the lift pump logic pin in from TIPM connector.

Toggle the lift pump actuator with the Electronic Service Tool.

Using a 12 volt test light connected to battery negative, check the lift pump circuit at the TIPM connector.


NOTE: The test light must illuminate brightly.

Compare the brightness to that of a direct connection to the battery.

Does the test light cycle on and off and illuminate brightly?

Yes

- Go To 3

No

- Replace the ECM.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

3. TIPM





Using a back probing tool 6801, back probe the lift pump power pin in from TIPM connector.

Toggle the lift pump actuator with the Electronic Service Tool.

Using a 12 volt test light connected to battery negative, check the lift pump circuit at the TIPM connector.


NOTE: The test light must illuminate brightly.

Compare the brightness to that of a direct connection to the battery.

Does the test light cycle on and off and illuminate brightly?

Yes

- Test complete.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Replace the TIPM
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test