Powertrain Controls - ECM/PCM

Code 54 Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION:

The status of the fuel pump CKT 458 is monitored for voltage by the ECM and is used to compensate fuel delivery based on system voltage. This signal is also used to store a code 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 CKT 458 for at least 2 seconds after the ignition is turned, or any time reference pulses are being received by the ECM.

Code 54 will set if the voltage on circuit 458 is less than 2 volts for 1.5 seconds since the last reference pulse was received. This code is designed to detect a faulty relay, causing extended crank time, and the code will help the diagnosis of an engine that "Cranks But Will Not Run."

If a fault is detected during start-up, the "SERVICE ENGINE SOON" light will stay "ON" until the ignition is cycled "OFF". However, if the voltage is detected below 2 volts with the engine running, the light will only remain "ON" while the condition exist.

The fuel pump test connector is located in the engine compartment, under the master cylinder near the vehicle battery.

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.