P0231

DTC P0231 Fuel Pump Feedback Circuit Low Voltage

Circuit Description

The status of the lift pump is monitored by the PCM. This signal is also used in order 10 store a DTC if the fuel pump relay is defective or if the fuel pump voltage is lost while the engine is running. There should be about 12 volts on circuit 120 during the glow plug cycle.

Conditions for Running the DTC

The fuel lift pump is commanded ON.

Conditions for Setting the DTC

^ The difference between the ignition voltage and the fuel pump voltage is greater than 4 volts.
^ All diagnostic set conditions met for 2 seconds.

Action Taken When the DTC Sets

^ The PCM illuminates Malfunction Indicator Lamp (MIL) on the second consecutive drive trip the diagnostic mns and fails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame records the operating conditions at the time of failure and updates the Failure Records.

Conditions for Clearing the MIL/DTC

^ The PCM will turn the MIL off after three consecutive trips without a fault condition.
^ A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from start up coolant temperature and the engine coolant temperature exceeds 71 °C (1 600 F) of that same ignition cycle).
^ Use of a scan tool will clear the DTC codes.

Diagnostic Aids

This DTC will not check the fuel pump for operation.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

3. This step checks the fuel lift pump circuit.