Powertrain Controls - ECM/PCM

Diagnostic Trouble Code 54:

Fuel Pump Control Wiring:

CIRCUIT DESCRIPTION
When the ignition switch is turned "ON," the Engine Control Module (ECM) will activate the fuel pump relay and run the in-tank fuel pump. The fuel pump will operate as long as the engine is cranking or running, and the ECM is receiving ignition reference pulses.

If there are no reference pulses, the ECM will shut "OFF" the fuel pump within 2 seconds after ignition "ON," or engine stops.

Should the fuel pump relay, or the 12 volts relay drive from the ECM fail, the fuel pump will be run through an oil pressure switch back-up circuit.

Diagnostic Trouble Code (DTC) 54 will set if the ECM detects less than 2 volts on CKT 120 during cranking or while the engine is running.

DIAGNOSTIC AIDS
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold or engine oil pressure is low. The extended crank period is caused by the time necessary for oil pressure to build enough to close the oil pressure switch and turn "ON" the fuel pump.