X115 - Continuous Code 556/557: Check EEC-IV Harness

A Continuous Memory Diagnostic Trouble Code (DTC) 556/557 indicates a fuel pump primary circuit failure has occurred during vehicle operation.

Possible causes are:
- Open VPWR in the Constant Control Relay Module (CCRM).
- Open coil in fuel pump relay.
- Open in fuel pump circuit (Powertrain Control Module (PCM) Pin 22 or 41)
- Start engine.

- Check for engine stall/stumble while performing the following (also, if possible, listen for fuel pump turning off):

- Shake, wiggle, bend the EEC-IV vehicle harness fuel pump circuit (Pin 22) between the PCM and the CCRM.

- Lightly tap the CCRM 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 dual Heated Oxygen Sensor (HO2S) applications with a DTC 524/543 only: Go to X116. X116 - Check Left Front HO2S Circuit For Short to Power

ALL others: For further diagnosis using the 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 X120. X120 - Road Test