• | 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 | * | ** | -- | -- |
Ignition 1 Voltage - Relay Coil | P1230 | P1230 | P0563 | -- |
Fuel Pump Supply Voltage | * | ** | *** | -- |
Fuel Pump Relay Control | P1230 | P1230 | P1231 | -- |
Fuel Pump Ground | -- | ** | -- | -- |
* The fuel pump fuse opens and the engine cranks but does not run. ** The engine cranks but does not run. *** The fuel pump operates continuously and the battery will discharge. |
The engine control module (ECM) provides a ground to the coil side of the fuel pump relay. When the ignition switch is first turned ON, the ECM energizes the fuel pump relay, which applies power to the fuel pump. The ECM enables the fuel pump relay as long as the engine is cranking or running, and crankshaft reference pulses are received. If no crankshaft reference pulses are received, the ECM de-energizes the fuel pump relay after about 3 seconds.
• | The ignition is ON or the engine is running. |
• | The DTCs runs continuously once the above conditions are met. |
The ECM detects the fuel pump relay control circuit is open or shorted to ground.
The ECM detects the fuel pump relay control circuit control circuit is shorted to voltage.
DTCs P1230 and P1231 are Type C DTCs.
DTCs P1230 and P1231 are Type C DTCs.
The following table illustrates the fuel pump relay terminal location in the underhood fuse block:
ENGINE Relay Terminal Identification | |
---|---|
B+ - Switch | FP Relay Control |
Ignition 1 Voltage - Coil | FP Motor |
Front of Vehicle |
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
• | J 35616 GM-Approved Terminal Test Kit |
• | J 43244 Relay Puller Pliers |
⇒ | If the test lamp does not illuminate, repair the relay coil supply circuit for a short to ground or an open/high resistance. |
⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If circuit tests normal, replace the ECM. |
⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal, replace the ECM. |
⇒ | If not within the specified range, replace the fuel pump relay. |
• | 30 and 86 |
• | 30 and 87 |
• | 30 and 85 |
• | 85 and 87 |
⇒ | If not the specified value, replace the fuel pump relay. |
⇒ | If greater than the specified range, replace the fuel pump relay. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |