P0231

Diagnostic Chart:

Schematic:

The PCM controls the fuel pump motor by supplying the fuel pump relay coil ignition voltage. The fuel pump runs continuously whenever the engine is running or runs for 2 seconds if the ignition is turned On and the engine is not cranked. The PCM controls an internal driver which supplies the fuel pump relay coil direct ignition voltage whenever the fuel pump relay is commanded On. The relay coil circuit is monitored for low and high voltage faults. DTC P0231 sets when the fuel pump relay is being commanded On and the feedback voltage at the PCM is low.

DTC PARAMETERS
DTC P0231 will set if fuel pump relay voltage is less than 2.5 volts when fuel pump relay is commanded On.

DTC P0231 diagnostic runs continuously with ignition On and fuel pump relay commanded On.

DTC P0231 is a type D DTC.

DIAGNOSTIC AIDS
To locate an intermittent problem, use Scan tool to command FUEL PUMP RELAY On, while monitoring the FUEL PUMP REL. - LOW VOLT test. When a fault (short to ground or shorted solenoid) exists, the Scan tool will display TEST FAIL.

The test will fail only when the device is being commanded On and the voltage at the PCM is low. The test updates every 100 ms whenever the ignition is turned On and the device is being commanded On via the Scan tool or PCM.

Fuel pump relay coil resistance: 75-105 ohms