Cruze

DTC P0628 or P0629

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 ECM 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 ECM turns OFF the fuel pump. The fuel pump relay control circuit is equipped with a feedback circuit that is pulled up to 2.5 V 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 00

The ECM detects the voltage on the fuel pump relay control circuit is within a predetermined range when the control circuit is commanded OFF. The condition exists for greater than 4 s, or a cumulative of 30 s.

P0628 00

The ECM detects the fuel pump relay control circuit voltage is less than 2.21 V when the control circuit is commanded ON. The condition exists for greater than 4 s, or a cumulative of 30 s.

P0629 00

The ECM detects the fuel pump relay control circuit voltage is greater than 2.21 V when the control circuit is commanded OFF. The condition exists for greater than 4 s, or a cumulative of 30 s.

DTCs P0628 00 and P0629 00 are Type B DTCs.

DTCs P0628 00 and P0629 00 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

Special Tools

EL-43244 Relay Puller Pliers

For equivalent regional tools, refer to Special Tools .

1. Ignition ON, select the output control Fuel Pump Relay with a scan tool. You should hear an audible click.
2. Attempt to start the engine. Observe the DTC information with a scan tool. DTC P0628 00, or P0629 00 should not set.
3. 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, remove the KR23A Fuel Pump Relay with the EL-43244 Relay Puller Pliers.
2. Connect a test lamp between the KR23A Fuel Pump Relay control circuit terminal 86 and ground.
3. Ignition ON, select the output control Fuel Pump Relay with a scan tool. The test lamp should turn ON and OFF as commanded.

⇒	If the test lamp remains OFF all the time, test for a short to ground or an open/high resistance on the control circuit. If circuit/connections test normal, replace the K20 Engine Control Module.

⇒	If the test lamp remains ON all the time, test for a short to voltage on the KR23A Fuel Pump Relay control circuit. If circuit/connections test normal, replace the K20 Engine Control Module.

4. Ignition OFF, connect a test lamp between the KR23A Fuel Pump Relay control circuit terminal 86 and the ground circuit terminal 85 of the KR23A Fuel Pump Relay.
5. Ignition ON, select the output control Fuel Pump Relay with a scan tool. The test lamp should turn ON and OFF as commanded.

⇒	If the test lamp does not turn ON when commanded, repair the open/high resistance in ground circuit terminal 86 of the KR23A Fuel Pump Relay.

6. If all circuits/connections test normal, test or replace the KR23A Fuel Pump Relay.

Static Test

1. Test for 70-110 Ω between terminals 85 and 86 of the KR23A Fuel Pump Relay.

⇒	If not within the specified range, replace the KR23A Fuel Pump Relay.

2. Test for infinite resistance between the following terminals of the KR23A Fuel Pump Relay:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If continuity is detected, replace the KR23A Fuel Pump Relay.

3. Connect a 20 A fused jumper wire from the positive terminal of the battery to KR23A Fuel Pump Relay terminal 85. Connect a jumper wire from the negative terminal of the battery to KR23A Fuel Pump Relay terminal 86. Test for less than 2 Ω between terminals 30 and 87 of the KR23A Fuel Pump Relay.

⇒	If greater than the specified range, replace the KR23A Fuel Pump Relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.