Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD1994F 150 2WD PICKUP L6-300 4.9LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSTESTING AND INSPECTIONPINPOINT TESTSX - CONSTANT CONTROL RELAY MODULE (CCRM)X80 - CODE 542: DOES ENGINE START
1994 Ford F 150 2WD Pickup L6-300 4.9L
X80 - Code 542: Does Engine Start
1994 Ford F 150 2WD Pickup L6-300 4.9LSECTION X80 - Code 542: 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. X81 - Verify Fuel Pump Is Off
No -- Go to X85. X85 - Check Inertia Fuel Shutoff Switch
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.