J1 - Check For VPWR to Fuel Pump Relay

Diagnostic Trouble Code (DTC) 556 indicates a fuel pump primary circuit failure.

Possible causes:

- Inertia Fuel Shutoff (IFS) switch not reset or electrically open (if in primary circuit).

- Open or shorted circuit.

- Damaged fuel pump relay.

- Damaged Powertrain Control Module (PCM).

- Disconnect fuel pump relay.

- Key "ON", engine "OFF".

- Measure voltage between VPWR circuit at the fuel pump relay vehicle harness connector and chassis ground.

- Is voltage greater than 10.5 volts?

Yes -- Go to J2. J2 - Check Fuel Pump Relay

No -- Verify integrity of IFS switch. If OK, service open in VPWR circuit between the Electronic Engine Controls (EEC) power relay and the fuel pump relay. Reconnect fuel pump relay. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)