Powertrain Controls - ECM/PCM

DTC 54 Fuel Pump Relay Diagnosis - Voltage Low:

Fuel Pump Relay Circuit:

CIRCUIT DESCRIPTION
The status of the fuel pump CKT 120 is monitored by the Powertrain Control Module (PCM) at terminal "B12" and is used to compensate fuel delivery based on system voltage. This signal is also used to store a Diagnostic Trouble Code (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 CKT 120 for at least 2 seconds after the ignition is turned "ON," or any time reference pulses are being received by the PCM.

DTC 54 WILL SET WHEN
The voltage at terminal "B12" is less than 2 volts for 1.5 seconds since the last reference pulse was received. This DTC is designed to detect a faulty relay, causing extended crank time, and the DTC will help the diagnosis of an engine that "Cranks But Will Not Run."

ACTION TAKEN (PCM WILL DEFAULT TO)
The PCM will enable the Malfunction Indicator Lamp (MIL).

DTC 54 WILL CLEAR WHEN
Conditions for fault are no longer present and Tech 1 scan tool clear DTCs function is used or 50 ignition switch keycycles have passed with no further faults or ignition switch is turned "OFF" and ECM "B" fuse is removed for 10 seconds.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart:

1. This step will determine if DTC 54 is the result of a hard failure or an intermittent condition.

2. This procedure applies direct voltage to run the fuel pump. If the pump runs, it may be a fuel pump relay circuit problem which the following step will locate.

3. This step checks voltage from the battery and the ground circuit to the relay.

4. This test determines if there is voltage from the PCM terminal, "F6" to the relay connector.

5. This step completes the fuel pump relay circuit but if this diagnosis was used because the engine would not run then the oil pressure switch should also be diagnosed.

DIAGNOSTIC AIDS
Refer to Intermittents. - Intermittent Malfunctions