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DTC P0627-P0629

DTC P0627-P0629

Diagnostic Instructions


• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• 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 Short to Ground Open/High Resistance Short to Voltage Signal Performance
Fuel Pump Enable P0628, P069E P0627, P069E P0629 -


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 (3.0L (LF1)) Engine Controls Schematics (2.8L (LAU))

Connector End View Reference

Component Connector End Views

Electrical Information Reference


• Circuit Testing

• Connector Repairs

• Testing for Intermittent Conditions and Poor Connections

• Wiring Repairs


DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification


1. Attempt to start the engine. Note the DTC information with a diagnostic tool. DTCs 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 20 of the fuel pump control module.

3. 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.

4. Ignition ON, command the Fuel Pump Enable ON with a scan tool. Test for B+ on the enable circuit terminal 20 of the fuel pump control module.

5. 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.

6. Ignition ON, test for 2-3 V on the enable circuit terminal 20 of the fuel pump control module.

7. If not within the specified range, replace the K20 ECM.

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


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM or fuel pump control module replacement, setup, and programming