DTC P0627, P0628, or P0629 W/LY7
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 Relay Control CircuitDTC P0628: Fuel Pump Relay Control Circuit Low Voltage
DTC P0629: Fuel Pump Relay Control Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Battery Voltage - Relay Switch | 1 | 2 | -- | -- |
Fuel Pump Supply Voltage | 1 | 2 | 3 | -- |
Fuel Pump Relay Control | P0628 | P0627 | P0629 | -- |
Fuel Pump Ground | -- | P0627 | -- | -- |
| ||||
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 control module 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 control module turns OFF the fuel pump. The fuel pump relay control circuit is equipped with a feedback circuit that is pulled up to 2.5 volts 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
| • | The engine speed is greater than 80 RPM. |
| • | The ignition voltage is 10-18 volts. |
| • | The ECM has commanded the fuel pump relay ON and OFF at least once during the ignition cycle. |
| • | The above conditions are met for less than 1 second. |
| • | The DTCs runs continuously once the above conditions are met. |
Conditions for Setting the DTC
P0627
The ECM detects the voltage on the fuel pump relay control circuit is within a predetermined range when the control circuit is commanded OFF. The condition exists for greater than 4 seconds, or a cumulative time of 30 seconds.
P0628
The ECM detects the fuel pump relay control circuit voltage is less than 2.21 volts when the control circuit is commanded ON. The condition exists for greater than 4 seconds, or a cumulative time of 30 seconds.
P0629
The ECM detects the fuel pump relay control circuit voltage is greater than 2.21 volts when the control circuit is commanded OFF. The condition exists for greater than 4 seconds, or a cumulative time 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
Connector End View Reference
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 an audible click.
- Attempt to start the engine. Observe the DTC information with a scan tool. DTC P0627, P0628, or P0629 should not set.
- 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 fuel pump relay.
- Connect a test lamp between the control circuit terminal 86 of the fuel pump relay and ground.
- Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF as commanded.
- Ignition OFF, connect a test lamp between the fuel pump relay control circuit terminal 86 and the ground circuit terminal 85 of the fuel pump relay.
- Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF as commanded.
- If all circuits/connections test normal, test or replace the fuel pump relay.
| ⇒ | If the test lamp remains OFF all the time, test for a short to ground or an open/high resistance on the control circuit. If circuit/connections test normal, replace the ECM. |
| ⇒ | If the test lamp remains ON all the time, test for a short to voltage on the control circuit. If circuit/connections test normal, replace the ECM. |
| ⇒ | If the test lamp does not turn ON when commanded, repair the open/high resistance in ground circuit of the fuel pump relay. |
Component Testing
- Test for 135-185 Ω between terminals 85 and 86 of the fuel pump relay.
- Test for infinite resistance between the following terminals of the fuel pump relay:
- Connect a 20 A fused jumper wire from the positive terminal of the battery to relay terminal 85. Connect a jumper wire from the negative terminal of the battery to relay terminal 86. Test for less than 2 Ω between terminals 30 and 87 of the relay.
| ⇒ | If not within the specified range, replace the fuel pump relay. |
| • | 30 and 86 |
| • | 30 and 87 |
| • | 30 and 85 |
| • | 85 and 87 |
| ⇒ | If continuity is detected, replace the fuel pump relay. |
| ⇒ | If greater than the specified range, replace the fuel pump relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
DTC P0627, P0628, or P0629 w/LLT
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 Control CircuitDTC P0628: Fuel Pump Control Circuit Low Voltage
DTC P0629: Fuel Pump Control Circuit High Voltage
Circuit/System Description
The engine control module (ECM) supplies voltage to the fuel pump flow control module (FPCM) when the ECM detects that the ignition is on. The voltage from the ECM to the FPCM remains active for 2 seconds, unless the engine is in crank or run. While this voltage is being received, the FPCM supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel rail pressure.
Conditions for Running the DTC
| • | The engine speed is greater than 80 RPM. |
| • | The ignition voltage is 10-18 volts. |
| • | The ECM has commanded the fuel pump relay ON and OFF at least once during the ignition cycle. |
| • | The above conditions are met for less than 1 second. |
| • | The DTCs runs continuously once the above conditions are met. |
Conditions for Setting the DTC
P0627
The ECM detects the voltage on the fuel pump control enable circuit is within a predetermined range when the control circuit is commanded OFF. The condition exists for greater than 4 seconds, or a cumulative time of 30 seconds.
P0628
The ECM detects the fuel pump control enable circuit voltage is less than 2.21 volts when the control circuit is commanded ON. The condition exists for greater than 4 seconds, or a cumulative time of 30 seconds.
P0629
The ECM detects the fuel pump control enable circuit voltage is greater than 2.21 volts when the control circuit is commanded OFF. The condition exists for greater than 4 seconds, or a cumulative time 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.
Diagnostic Aids
Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
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, observe the DTC information with a scan tool. DTC P069E should not be set.
| ⇒ | If the DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis of FPCM DTCs. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
