The engine control module (ECM) provides ignition voltage to the coil side of the fuel pump relay whenever the engine is cranking or running. The control module enables the fuel pump relay as long as the engine is cranking or running, and ignition system reference pulses are received. If no ignition system reference pulses are received, the control module turns OFF the fuel pump. The fuel pump relay control circuit is equipped with a feedback circuit that is pulled up to 2.5 volts within the ECM. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

P0627

The ECM detects the fuel pump relay control circuit is open.

P0628

The ECM detects the fuel pump relay control circuit is shorted to ground.

P0629

The ECM detects the fuel pump relay control circuit control circuit is shorted to voltage.

DTCs P0627, P0628 and P0629 are Type B DTCs.

DTCs P0627, P0628 and P0629 are Type B DTCs.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, command the Fuel Pump Relay ON and OFF with a scan tool. You should hear and feel an audible click.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the fuel pump relay.
2. Connect a test lamp between the relay coil control circuit terminal 86 and ground.
3. Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

4. Ignition OFF, connect a test lamp between the relay coil control circuit terminal 86 and the ground circuit terminal 85.
5. Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always OFF, repair the ground circuit for an open/high resistance.

6. If all circuits test normal, test or replace the fuel pump relay.

1. Ignition OFF, disconnect the fuel pump relay.
2. Test for 70-110 ohms of resistance between terminals 85 and 86.

⇒	If not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not within the specified range, replace the relay.

4. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87.

⇒	If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.