DTC P0627 or P0628 - LNP or LNQ
Diagnostic Instructions
DTC Descriptors
DTC P0627 00: Fuel Pump Relay Control Circuit High Voltage
DTC P0628 00: Fuel Pump Relay Control Circuit Low Voltage
Diagnostic Fault Information
Circuit
| Short to Ground
| Open/High Resistance
| Short to Voltage
| Signal Performance
|
Relay Coil Control
| P0628 00
| P0627 00
| P0627 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 power stage is not active. |
• | The DTCs run continuously once 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 once 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.
Action Taken When the DTC Sets
DTC P0627 00, and P0628 00 are Type A DTCs.
Conditions for Clearing the DTC
DTC P0627 00, and P0628 00 are Type A DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, command the Fuel Pump Relay ON and OFF with a scan tool. You should hear and feel an audible click.
- 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
- Ignition OFF, disconnect the KR23A Fuel Pump Relay.
- Test for less than 5 Ω between the ground circuit terminal 86 and ground.
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
- Connect a test lamp between the control circuit terminal 85 and ground.
- 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. |
- If all circuits test normal, test or replace the KR23A Fuel Pump Relay.
Component Testing
Relay Test
- Ignition OFF, disconnect the fuel pump relay.
- Test for 70-110 Ω of resistance between terminals 85 and 86.
⇒ | If not within the specified range, replace the KR23A Fuel Pump Relay. |
- Test for infinite resistance between the following terminals:
⇒ | If not the specified value, replace the KR23A Fuel Pump Relay. |
- 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 of resistance between terminals 30 and 87.
⇒ | If greater than the specified range, replace the KR23A Fuel Pump Relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
© Copyright Chevrolet. All rights reserved |
© Copyright Chevrolet. All rights reserved |