P0629
DTC P0627-P0629 (LUW)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P0627
- Fuel Pump Enable Circuit Open
DTC P0628
- Fuel Pump Enable Circuit Low Voltage
DTC P0629
- Fuel Pump Enable Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The engine control module (ECM) provides ignition voltage to the fuel pump control module (FPCM) whenever the engine is cranking or running. The control module 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 in-tank fuel pump module in order to maintain the desired fuel line pressure.
Conditions for Running the DTC
* The ignition voltage is between 11-32 V.
* The engine speed is greater than 0 RPM.
* The DTCs run continuously when the above conditions are met for greater than 2 s.
Conditions for Setting the DTC
P0627
The ECM detects the fuel pump enable circuit is open.
P0628
The ECM detects the fuel pump enable circuit is shorted to ground.
P0629
The ECM detects the fuel pump enable circuit is shorted to voltage.
Action Taken When the DTC Sets
DTCs P0627, P0628, and P0629 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P0627, P0628, and P0629 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Fuel System Description Fuel System Description
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
Note: If you were sent here from engine cranks but does not run proceed to Circuit/System Testing.
1. Attempt to start the engine. Observe the DTC information with a scan tool. DTC P0627, P0628, or P0629 should not set.
2. Ignition ON, command the Fuel Pump Enable ON and OFF with a scan tool while observing the following control circuit status parameters. Each parameter should display OK or Not Run.
* Fuel Pump Enable Circuit Low Voltage Test Status
* Fuel Pump Enable Circuit Open Test Status
* Fuel Pump Enable Circuit High Voltage test Status
3. Ignition ON, view the DTC information with a scan tool. DTC P0627, P0628, or P0629 should not be set.
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.
Circuit/System Testing
1. Ignition OFF, disconnect the K27 Fuel Pump Control Module harness connector.
2. Ignition OFF, and all vehicle systems OFF. It may take up to 2 min for all vehicle systems to power down. Test for less than 5 ohms between the ground circuit terminal 25 and ground.
• If greater than the specified range, test the ground circuit for an open/High resistance.
3. Ignition OFF, Test for 0 V between the enable circuit terminal 20 and ground.
• If greater than the specified value, test the enable circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.
4. Ignition ON, command the Fuel Pump Enable ON with a scan tool. Test for B+ between the enable circuit terminal 20 and ground.
• If less than the specified range, test the enable circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.
5. If all circuits test normal, replace the K27 Fuel Pump Control Module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
Control Module References Control Module References for FPCM or ECM replacement, programming and setup.