Volt

DTC P0628 or P0629

The engine control module (ECM) provides ignition voltage to the fuel pump flow control module whenever the engine is cranking or running. The ECM enables the fuel pump flow control module as long as the engine is cranking or running, and ignition system reference pulses are received. While this enable voltage is being received, the fuel pump flow control module supplies a varying voltage to the fuel tank fuel pump module in order to maintain the desired fuel line pressure.

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 2.5 s.

DTCs P0628 and P0629 are Type B DTCs.

DTCs P0628 and P0629 are Type B DTCs.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Hybrid Modes of Operation Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Attempt to start the engine. Observe the DTC information with a scan tool. DTC P0628 or P0629 should not set.
2. Vehicle in Service Mode, command the Fuel Pump Enable ON and OFF with a scan tool while observing the control circuit status parameters listed below:

•	Fuel Pump Enable Circuit Low Voltage Test Status

•	Fuel Pump Enable Circuit Open Test Status

•	Fuel Pump Enable Circuit High Voltage Test Status

Each parameter should toggle between OK and Not Run or Not Run and OK.

3. Engine running, command the Fuel Pump Enable ON and OFF with a scan tool while observing the control circuit status parameters listed below:

•	Fuel Pump Enable Circuit Low Voltage Test Status

•	Fuel Pump Enable Circuit Open Test Status

•	Fuel Pump Enable Circuit High Voltage Test Status

Each parameter should toggle between OK and Not Run or Not Run and OK.

4. 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. Vehicle OFF, disconnect the K27 fuel pump control module harness connector.
2. Vehicle OFF, all systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for 0 V on the enable circuit terminal 20.

⇒	If greater than the specified value, test for a short to voltage on the enable circuit. If the circuit/connections test normal, replace the K20 ECM.

3. Vehicle in Service Mode, command the Fuel Pump Enable ON with a scan tool.
4. Test for B+ on the enable circuit terminal 20.

⇒	If less than the specified range, test for a short to ground or an open/high resistance on the enable circuit. If the circuit/connections test normal, replace the K20 ECM.

5. If all circuits/connections test normal, replace the K27 fuel pump control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.