P0231

Diagnostic Chart:

Wiring Diagram:

Circuit Description

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

Conditions for Setting the DTC

^ The PCM performs this DTC diagnostic continuously.

^ The fuel lift pump is commanded ON.

^ The difference between ignition voltage and fuel pump voltage is greater than 4 volts.

^ All diagnostic conditions met for 2 seconds.

Action Taken When the DTC Sets

^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails.

^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records will 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 when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.

^ Use of a Scan Tool

Diagnostic Aids

This DTC will not check the fuel pump 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.