P0628
DTC P0627-P0629 (LUW)
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 Relay Control Circuit Open
DTC P0628
- Fuel Pump Relay Control Circuit Low Voltage
DTC P0629
- Fuel Pump Relay Control Circuit High Voltage
Diagnostic Fault Information
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 and P0629
* The ignition voltage is between 11-32 V.
* The ECM has commanded the fuel pump OFF.
* The above conditions are met for greater than 1 s.
* The DTCs run continuously when the above conditions are met.
P0628
* The ignition voltage is between 11-32 V.
* The ECM has commanded the fuel pump ON.
* The above conditions are met for greater than 1 s.
* The DTC runs continuously when the above conditions are met.
Conditions for Setting the DTC
P0627
The ECM detects the fuel pump relay control circuit is open.
P0628
The ECM detects the fuel pump relay control circuit is shorted to ground.
P0629
The ECM detects the fuel pump relay control circuit is shorted to voltage.
Action Taken When the DTC Sets
DTCs P0627, P0628, and P0629 are Type C DTCs.
Conditions for Clearing the DTC
DTCs P0627, P0628, and P0629 are Type C DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics (LUW) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Sunshade - Left (D6I)
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
Note: If you were sent here from engine cranks but does not run proceed to Circuit/System Testing.
1. Ignition ON, command the Fuel Pump Relay ON and OFF with a scan tool. You should hear and feel an audible click with the KR23A Fuel Pump Relay.
2. Ignition ON, view the DTC information with a scan tool. DTC P0627, P0628, or P06290 should not be set.
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, remove the KR23A Fuel Pump Relay, from the underhood fuse block.
2. Test for less than 5 ohm between the ground circuit terminal 86 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal 85 and ground.
4. 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.
• 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.
• 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.
5. If all circuits test normal, test or replace the KR23A Fuel Pump Relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the KR23A Fuel Pump Relay.
2. Measure for 70-110 ohmbetween terminals 85 and 86 of the KR23A Fuel Pump Relay.
• If the resistance is not within the specified range, replace the KR23A Fuel Pump Relay.
3. Measure for infinite resistance between following terminals of the KR23A Fuel Pump Relay:
* Terminals 30 and 86
* Terminals 30 and 87
* Terminals 30 and 85
* Terminals 85 and 87
• If continuity is detected, replace the KR23A Fuel Pump Relay.
4. Connect a 20 A fused jumper wire from the positive terminal of the battery to KR23A Fuel Pump Relay terminal 85. Connect a jumper wire from the negative terminal of the battery to KR23A Fuel Pump Relay terminal 86. Measure for less than 5 ohm between KR23A Fuel Pump Relay terminal 30 and KR23A Fuel Pump Relay socket terminal 87.
• If the resistance measures more than 5 ohm, replace the KR23A Fuel Pump Relay.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)
* Control Module References Control Module References for ECM replacement, programming and setup