P0628

P0628-LOW 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 circuit in the TIPM does not match the feedback signal from the fuel lift pump circuit.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test


1. POWER AT TIPM

Using a voltmeter, measure the voltage on the Battery Supply wire to the TIPM.

Turn the ignition on, engine off.

Does the voltmeter show battery voltage?

No

- Fix or replace the open circuit in the Battery Supply Circuit.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

Yes

- Go To 2

2. DAMAGED WIRING HARNESS

Turn Ignition off.

Disconnect the ECM and TIPM connectors. Inspect the connectors for signs of damage or corrosion.


NOTE: Check connectors - Clean/repair as necessary.

Are any pins damaged?

Yes

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

No

- Go To 5

3. FUEL LIFT PUMP CONTROL CIRCUIT OPEN





Using an ohmmeter, measure the resistance of the lift pump control circuit between the ECM connector and the TIPM connector.

Is the resistance less than 10 Ohms?

Yes

- Go To 4

No

- Repair the open ground circuit.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. FUEL LIFT PUMP CONTROL CIRCUIT SHORTED TO EXTERNAL VOLTAGE





Using a voltmeter, measure the voltage between battery negative and the lift pump control circuit at the TIPM connector.

Is the voltage greater than 1 volt?

No

- Go To 5

Yes

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

5. FUEL LIFT PUMP CONTROL CIRCUIT SHORTED TO OTHER CIRCUITS





Using an ohmmeter, measure the resistance between the lift pump control circuit in the ECM connector and all other circuits in the ECM connectors.

Is the resistance less than 10 Ohms?

Yes

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

No

- Go To 6

6. FUEL LIFT PUMP CONTROL CIRCUIT SHORTED TO EXTERNAL VOLTAGE





Connect the ECM and TIPM connectors.

Using a back probing tool 6801, back probe the lift pump control circuit 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?

No

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

Yes

- Go To 7

7. FUEL LIFT PUMP DRIVER CIRCUIT SHORTED TO OTHER CIRCUITS

Using a back probing tool, back probe the lift pump control circuit in the TIPM connector.

Toggle the lift pump actuator with the scan Tool.

Using a 12 volt test light connected to battery negative, check the lift pump control 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