DTC 542
Fuel pump secondary circuit failure.
KOEO Hard Code Go to X80
See: Diagnostic Charts (Pinpoint Tests)\X - Constant Control Relay Module\X80 - Does Engine Start
KOEO Memory Code Go to X105
See: Diagnostic Charts (Pinpoint Tests)\X - Constant Control Relay Module\X105 - Continuous Code 542: Check EEC-IV Harness
X80 - Does Engine Start
Diagnostic Trouble Code (DTC) 542 indicates that one of the following has occurred:
No Start:
Inertia Fuel Shutoff (IFS) switch not reset or electrically open (if in secondary circuit).
Open circuit between the fuel pump and Fuel Pump Monitor (FPM) circuit connection to power-to-pump circuit.
Poor fuel pump ground.
Fuel pump electrically open.
Engine Starts:
Fuel pump secondary circuit short to power.
Fuel pump relay contacts always closed.
Open in FPM circuit between Powertrain Control Module (PCM) and connection to power-to-pump circuit.
Left/Front Heated Oxygen Sensor (HO2S) short to power (dual HO2S applications).
Damaged PCM.
Does the engine start?
Yes -- Go to X81. See: X81 - Verify Fuel Pump Is Off
No -- Go to X85. See: X85 - Check Inertia Fuel Shutoff Switch
OR
X105 - Continuous Code 542: Check EEC-IV Harness
A Continuous Memory Diagnostic Trouble Code (DTC) 542 indicates that one of the following intermittent conditions has occurred:
Fuel pump circuit activated when Powertrain Control Module (PCM) expected circuit to be off (i.e. fuel system test or prime procedure).
Inertia Fuel Shutoff switch was tripped, then reset.
Open circuit in or between the fuel pump and Fuel Pump Monitor (FPM) circuit at the PCM (refer to schematic). See: Testing Schematic
Poor fuel pump ground.
FPM or power-to-pump circuit short to power.
Fuel pump relay contacts stuck closed.
Left/Front Heated Oxygen Sensor (HO2S) circuit short to power (w/dual HO2S).
Engine stall due to excessive load.
Start engine.
Check for engine stall/stumble while performing the following (also, if possible, listen for fuel pump turning off):
Shake, wiggle, bend the Power-To-Pump circuit between the Constant Control Relay Module (CCRM) Pin 5 and the fuel pump.
Shake, wiggle, bend the fuel pump ground circuit from the fuel pump to ground.
Lightly tap the fuel pump to simulate road shock.
Lightly tap Inertia Fuel Shutoff switch to simulate road shock.
Key "OFF".
Inspect the fuel pump vehicle harness connector and the fuel pump ground for corrosion, damaged pins, etc.
Is fault indicated/found?
Yes -- Isolate fault and service as necessary. Clear continuous memory DTC. See: Quick Test (Extracting and Clearing Codes)\Clearing Codes
Rerun quick test. See: Quick Test (Extracting and Clearing Codes)\Key On Engine Off (KOEO) Self Test
No -- Go to X106. See: X106 - Check FPM Circuit
