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 TESTSJ - FUEL PUMP CIRCUITJ95 - CHECK EEC-IV HARNESS
1994 Ford F 150 2WD Pickup L6-300 4.9L
J95 - Check EEC-IV Harness
1994 Ford F 150 2WD Pickup L6-300 4.9LSECTION J95 - Check EEC-IV Harness
A Continuous Memory Diagnostic Trouble Code (DTC) 556 indicates that a fuel pump primary circuit failure has occurred during vehicle operation.
Possible causes are:
- Open in VPWR circuit between the Electronic Engine Controls (EEC) power relay and the fuel pump relay.
- Open coil in fuel pump relay.
- Open in fuel pump circuit (Pin 22).
- Start engine.
- Check for engine stall/stumble while performing the following (also, if possible, listen for fuel pump turning off):
- Shake, wiggle, bend the VPWR circuit between the EEC power relay and the fuel pump relay. For vehicles with the Inertia Fuel Shutoff (IFS) switch in the VPWR circuit (refer to schematic), lightly tap the Inertia Fuel Shutoff (IFS) switch to simulate road shock.
- Shake, wiggle, bend the Powertrain Control Module (PCM) vehicle harness fuel pump circuit (Pin 22) between the PCM and the fuel pump relay.
- Lightly tap the fuel pump relay to simulate road shock.
- Key "OFF".
- Inspect the PCM connector and the fuel pump relay connectors for corrosion, damaged pins, etc.
- Is fault indicated/found?
Yes -- Isolate fault and service as necessary. Clear continuous memory. Clearing Diagnostic Trouble Codes
Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)
No -- For further diagnosis using an Electronic Engine Controls (EEC)-IV monitor box or Scan Tool, go to Normal Scan Data Values. If an EEC-IV monitor box or Scan Tool is not available, go to J99. J99 - Road Test
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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.