P0627
DTC P0627-P0629
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
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 relay control circuit whenever the engine is cranking or running. The ECM enables the fuel pump relay as long as the engine is cranking or running, and crank sensor reference pulses are received. The ECM monitors the voltage on the control circuit and sets a DTC if a fault is detected.
Conditions for Running the DTC
* The engine speed is greater than 80 RPM.
* The ignition 1 signal parameter is 10-18 V.
* The ECM has commanded the fuel pump enable circuit ON and OFF at least once during the ignition cycle.
* The DTCs run continuously when the conditions above are met.
Conditions for Setting the DTC
P0627
* The ECM detects the fuel pump control circuit voltage is less than 2.74 V when the control circuit is commanded OFF.
* The above condition exists for greater than 4 seconds, or a cumulative of 30 seconds.
P0628
* The ECM detects the fuel pump control circuit voltage is less than 2.21 V when the control circuit is commanded ON.
* The above condition exists for greater than 4 seconds, or a cumulative of 30 seconds.
P0629
* The ECM detects the fuel pump control circuit voltage is greater than 2.21 V when the control circuit is commanded OFF.
* The above condition exists for greater than 4 seconds, or a cumulative of 30 seconds.
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 (Connector End Views By Name)
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 (Programming and Relearning)for scan tool information
Special Tools
J 43244 Relay Puller Pliers
Circuit/System Verification
1. Ignition ON, command the fuel pump relay ON and OFF with a scan tool. You should hear and feel a click when you command the fuel pump relay ON and OFF.
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.
Circuit/System Testing
1. Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. The fuel pump should not be running.
• If the fuel pump runs continuously, test the component control circuit for a short to voltage. If the circuit tests normal, replace the KR107 fuel pump relay.
2. Remove the fuel pump relay from the electrical center with the J 43244 .
3. Test for less than 5 ohm between the ground circuit terminal 85 and ground.
• If greater than the specified range, repair the open/high resistance in the ground circuit.
4. Connect a test lamp between the relay control circuit terminal 86 and ground.
5. Ignition ON, command the fuel pump relay ON and OFF with a scan tool. The test lamp should turn ON and OFF with each command.
• If the test lamp is always ON, test the relay control circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
• If the test lamp is always OFF, test the relay control circuit for a short to ground or an open/high resistance. If circuit tests normal, replace the K20 engine control module.
6. If all circuits test normal, replace the KR107 fuel pump relay.
Component Testing
1. Ignition OFF, remove the KR107 fuel pump relay from the electrical center with the J 43244 .
2. Test for 70-110 ohm between terminals 85 and 86 of the KR107 fuel pump relay.
• If not within the specified range, replace the KR107 fuel pump relay.
3. Test for infinite resistance between the following relay terminals:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
• If not the specified value, replace the KR107 fuel pump relay.
4. Install a 20 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohm between relay terminals 30 and 87.
• If greater than the specified range, replace the KR107 fuel pump relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Refer to Control Module References (Programming and Relearning) for ECM replacement, programming, and setup.