P0629
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 flow control module 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 engine speed is greater than 0 RPM.
* The ignition voltage is between 11-18 V.
* The DTCs run continuously when the conditions above are met.
Conditions for Setting the DTC
* The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match.
* The above condition is met for a minimum of 2.5 s.
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 A/C Compressor Clutch
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
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:
* 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. 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 minutes for all vehicle systems to power down. Test for 0 V on the enable circuit terminal 13 of the fuel pump control module.
• 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. Ignition ON, command the Fuel Pump Enable ON with a scan tool. Test for B+ on the enable circuit terminal 13 of the fuel pump control module.
• 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.
4. If all circuits/connections test normal, replace the K27 fuel pump control module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Control Module References Control Module References for ECM or fuel pump control module replacement, setup, and programming