• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Battery Voltage - Relay Switch Side | ¹ | ² | -- | -- |
Fuel Pump Supply Voltage | ¹ | ² | ³ | -- |
Fuel Pump Relay Control | P0628 | P0627 | P0629 | -- |
Fuel Pump Relay Ground | -- | P0627 | -- | -- |
Fuel Pump Ground | -- | ² | -- | -- |
¹ Open fuel pump fuse, cranks, no start ² Cranks, no start ³ Fuel pump operates continuously, discharges battery |
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 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.
• | The engine speed is greater than 80 RPM. |
• | The ignition voltage is between 10-18.1 volts. |
• | The ECM has commanded the fuel pump relay OFF. |
• | The above conditions are met for greater than 1 second. |
• | The DTCs run continuously once the above conditions are met. |
• | The engine speed is greater than 80 RPM. |
• | The ignition voltage is between 10-18.1 volts. |
• | The ECM has commanded the fuel pump relay ON. |
• | The above conditions are met for greater than 1 second. |
• | The DTC runs continuously once the above conditions are met. |
The ECM detects the fuel pump relay control circuit is open.
The ECM detects the fuel pump relay control circuit is shorted to ground.
The ECM detects the fuel pump relay control circuit is shorted to voltage.
The DTCs set when the above conditions are met for more than 4 seconds or a cumulative of 50 seconds.
DTCs P0627, P0628, and P0629 are Type B DTCs.
DTCs P0627, P0628, and P0629 are Type B DTCs.
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
J 43244 Relay Puller Pliers
Important: An open or a short to voltage in the control circuit will cause both the Ckt. Open Test Status and the Ckt. Short Volts Test Status parameters to display Fault.
• | Fuel pump relay Ckt. Short Gnd Test Status |
• | Fuel pump relay Ckt. Open Test Status |
• | Fuel pump relay Ckt. Short Volts Test Status |
⇒ | If the test lamp does not illuminate, test the ground circuit for a short to voltage or an open/high resistance. |
⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
⇒ | If not the specified value, test the fuel pump relay control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
⇒ | If not the specified value, test the fuel pump relay control circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
⇒ | If the fuel pump does not activate, test the supply voltage circuit of the fuel pump for a short to ground or an open/high resistance. If the circuit tests normal, replace the fuel pump module. |
⇒ | If the fuel pump does not activate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and it's fuse is open, test or replace the relay. |
⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
⇒ | If the resistance is not within the specified range, replace the relay. |
• | 30 and 86 |
• | 30 and 87 |
• | 30 and 85 |
• | 85 and 87 |
⇒ | If not the specified value, replace the relay. |
⇒ | If greater than the specified range, replace the relay. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |