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 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 1-2 Shift Solenoid (SS) Valve (M30)

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

Special Tools

J 43244 - Relay Puller Pliers

Circuit/System Verification

1. Ignition ON.

2. 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.

• If a click is not heard or felt
Refer to Circuit/System Testing.

• If a click is heard or felt

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.

• If DTC resets
Refer to Circuit/System Testing.

• If DTC does not reset

4. All OK.

Circuit/System Testing

1. Ignition OFF.

2. Verify that the fuel pump is not running.

• If fuel pump is running
Test the component control circuit for a short to voltage. If the circuit tests normal, replace the KR107 Fuel Pump Relay.

• If fuel pump is not running

3. Remove the fuel pump relay from the electrical center with the J 43244 - Relay Puller Pliers.

4. Test for less than 5 ohms between the ground circuit terminal 85 and ground.

• If greater than 5 ohms
Repair the open/high resistance in the ground circuit.

• If less than 5 ohms

5. Connect a test lamp between the relay control circuit terminal 86 and ground.

6. Ignition ON.

7. 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.

• If the test lamp turns ON and OFF

8. Replace the KR107 Fuel Pump Relay.

Component Testing

1. Ignition OFF.

2. Remove the KR107 Fuel Pump Relay from the electrical center with the J 43244 - Relay Puller Pliers.

3. Test for 70 to110 ohms between terminals 85 and 86 of the KR107 fuel pump relay.

• If not within 70 to 110 ohms
Replace the KR107 Fuel Pump Relay.

• If within 70 to 110 ohms

4. Test for infinite resistance between the following relay terminals:

* 30 and 86

* 30 and 87

* 30 and 85

* 85 and 87

• If there is not infinite resistance
Replace the KR107 Fuel Pump Relay.

• If there is infinite resistance

5. Install a 20 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground.

6. Test for less than 2 ohms between relay terminals 30 and 87.

• If greater than 2 ohms
Replace the KR107 Fuel Pump Relay.

• If less than 2 ohms

7. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

Refer to Control Module References Control Module References for ECM replacement, programming, and setup