P0627
DTC P0627, P0628, or P0629
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0627
- Fuel Pump Enable Circuit
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 flow control module (FPCM) whenever the engine is cranking or running. The control module enables the FPCM as long as the engine is cranking or running, and ignition system reference pulses are received. While this enable voltage is being received, the FPCM 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 engine speed is greater than 0 RPM.
* The ignition voltage is 10-18 volts.
* The ECM has enabled the fuel pump control module (FPCM) at least once during the ignition cycle.
* The DTCs runs continuously once the above conditions are met for greater than 1 second.
Conditions for Setting the DTC
P0627
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 seconds.
P0628
The ECM detects the fuel pump relay control circuit voltage is less than 2.21 volts when the control circuit is commanded ON. The condition exists for greater than 5 seconds.
P0629
The ECM detects the fuel pump relay control circuit voltage is greater than 2.21 volts when the control circuit is commanded OFF. The condition exists for greater than 4 seconds.
Action Taken When the DTC Sets
DTCs P0627, P0628 and P0629 are Type C DTCs.
Conditions for Clearing the DTC
DTCs P0627, P0628 and P0629 are Type C DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition OFF, open the hood to disable the Auto-Stop function.
2. Ignition ON, verify the scan tool hood position parameter displays Open.
• If the hood position does not display Open, refer to DTC P254F (P254F).
3. Attempt to start the engine. Observe the DTC information with a scan tool. DTC P0627, P0628, or P0629 should not 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, open the hood to disable the Auto-Stop function.
2. Ignition ON, verify the scan tool hood position parameter displays Open.
• If the hood position does not display Open, refer to DTC P254F (P254F).
3. Ignition OFF, disconnect the fuel pump control module (FPCM) harness connector.
4. Ignition ON, test for 2-3 V between the enable circuit terminal 13 and ground.
• If less than the specified range, test the enable circuit for a short to ground, or an open/high resistance. If the circuit/connections test normal, replace the ECM.
• If greater than the specified range, test the enable circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
5. Command the fuel pump ON and OFF with a scan tool. The DMM should transition from 2-3 V when OFF, to greater than 10 V when commanded ON.
• If the circuit voltage does not correspond to the specified values, replace the ECM
6. If all circuits test normal, replace the FPCM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Fuel Pump Flow Control Module Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for engine control module replacement, setup, and programming