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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 00

Fuel Pump Relay Control Circuit Open

DTC P0628 00

Fuel Pump Relay Control Circuit Low Voltage

DTC P0629 00

Fuel Pump Relay Control Circuit High Voltage

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Relay Coil Control

P0628 00

P0627 00

P0629 00

-

Relay Coil Ground

-

-

-

-



Circuit/System Description

The engine control module (ECM) provides ignition voltage to the coil side of the fuel pump relay whenever the engine is cranking or running. The ECM enables the fuel pump relay as long as the engine is cranking or running, and ignition system reference pulses are received. If no ignition system reference pulses are received, the ECM turns OFF the fuel pump. The fuel pump relay control circuit is equipped with a feedback circuit that is pulled up to voltage within the ECM. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

Conditions for Running the DTC


P0627 00 and P0628 00

• The ignition is ON.

• The power stage is not active.

• The DTCs run continuously when the above conditions are met.



P0629 00

• The ignition is ON or the engine is running.

• The power stage is active.

• The DTCs run continuously when the above conditions are met.


Conditions for Setting the DTC

P0627 00

The ECM detects the fuel pump relay control circuit is open for greater than 1 s.

P0628 00

The ECM detects the fuel pump relay control circuit is shorted to ground for greater than 1 s.

P0629 00

The ECM detects the fuel pump relay control circuit is shorted to battery for greater than 1 s.

Action Taken When the DTC Sets

DTC P0627, P0628 and P0629 are Type A DTCs.

Conditions for Clearing the DTC

DTC P0627, P0628 and P0629 are Type A DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

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

Circuit/System Verification


1. Ignition ON, command the Fuel Pump Relay ON and OFF with a scan tool. You should hear and feel an audible click.

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, disconnect the KR23A Fuel Pump Relay.

2. Test for less than 5 Ω between the ground circuit terminal 85 and ground.

3. If greater than the specified range, test the ground circuit for an open/high resistance.

4. Connect a test lamp between the 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 when changing between the commanded states.

6. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.

7. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

8. If all circuits test normal, test or replace the KR23A Fuel Pump Relay.


Component Testing


Relay Test

1. Ignition OFF, disconnect the fuel pump relay.

2. Test for 70-110 Ω between terminals 85 and 86.

3. If not within the specified range, replace the KR23A Fuel Pump Relay.

4. Test for infinite resistance between the following terminals:

• 30 and 86

• 30 and 87

• 30 and 85

• 85 and 87

5. If not the specified value, replace the KR23A Fuel Pump Relay.

6. Install a 20 A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.

7. If greater than the specified range, replace the KR23A Fuel Pump Relay.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Relay Replacement (Attached to Wire Harness) Relay Replacement (Within an Electrical Center)

• Control Module References