P0231

CIRCUIT DESCRIPTION

The fuel pump receives power from CKT 120 through the fuel pump relay. The PCM energizes the fuel pump relay for 2 seconds at key ON to provide fuel pressure for starting. After the 2 second fuel pump prime, the PCM will not power the fuel pump relay until 4X reference pulses are received indicating that the engine is turning (crank or run). The PCM monitors voltage on the fuel pump power CKT 120 to detect fuel pump voltage supply faults. DTC P0231 is set when the PCM sees the fuel pump not energized (2 volts or less on the feedback) with the engine cranking or running.

CONDITIONS FOR SETTING THE DTC

Test Condition

Engine speed 24 RPM or greater.

Failure Condition

Fuel pump feedback 2 volts or less for 1.3 seconds.

ACTION TAKEN WHEN THE DTC SETS

^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The PCM will command a message to be displayed.
^ The PCM may record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records.

CONDITIONS FOR CLEARING THE MESSAGE/DTC

^ The PCM will turn the message OFF after one run and pass of the diagnostic test.
^ A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.
^ A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
^ PCM battery voltage is interrupted.
^ Using a Scan tool.

DIAGNOSTIC AIDS

If this DTC set without a driveability complaint look for an open between splice and PCM or poor PCM terminal contact. If a complaint did exist look for poor relay contact, relay ground, etc.