The engine control module (ECM) provides a ground to the coil side of the fuel pump relay. When the ignition switch is first turned On, the ECM energizes the fuel pump relay, which applies power to the fuel pump. The ECM enables the fuel pump relay as long as the engine is cranking or running, and crankshaft reference pulses are received. If no crankshaft reference pulses are received, the ECM de-energizes the fuel pump relay after about 3 seconds.

P0628

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

P0629

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

DTC P0628 and P0629 are Type C DTCs.

DTC P0628 and P0629 are Type C DTCs.

The following table illustrates the fuel pump relay terminal location in the underhood fuse block:

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 with a scan tool. You should hear an audible click for about 3-5 seconds.
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 harness connector at the fuel pump relay.
2. Ignition ON, command the fuel pump relay ON with a scan tool. Test for battery voltage between the relay coil ignition 1 voltage circuit terminal 86 and ground.

⇒	If less than B+, repair the relay switch ignition 1 voltage circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect a test lamp between the relay switch control circuit terminal 85 and the ignition 1 voltage circuit terminal 86.
4. Ignition ON, command the fuel pump relay ON with a scan tool. The test lamp should turn ON for about 3-5 seconds and then turn OFF.

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

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

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

1. Ignition OFF, disconnect the harness connector at 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 fuel pump relay.

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified value, replace the fuel pump relay.

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

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.