X111 - Check EEC-IV Harness

A Continuous Memory Diagnostic Trouble Code (DTC) 524/543, without the presence of a Continuous Memory DTC 556/557, indicates that during vehicle operation, one of the following has occurred:

- Open in the B(+) circuit between B(+) and the fuel pump relay.

- Fuel pump relay contacts opened.

- Open in the power-to-pump circuit from the Constant Control Relay Module (CCRM) / LFP relay to the Fuel Pump Monitor (FPM) splice.

- Left/Front Heated Oxygen Sensor (HO2S) circuit short to power (w/dual HO2S).

NOTE: DTC 524 refers to the low speed fuel pump circuit and DTC 543 refers to the high speed fuel pump circuit. Also, the Low Speed Fuel Pump (LFP) relay is external to the CCRM

- Start engine.

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

- Shake, wiggle, bend the fuel pump relay B(+) circuit to the CCRM/LFP relay.

- Lightly tap the CCRM/LFP relay (to simulate road shock).

- Shake, wiggle, bend the power-to-pump circuit from the CCRM/LFP relay to the FPM splice.

- Key "OFF".

- Inspect the CCRM/LFP relay connector and B(+) connector terminal 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 -- Under certain conditions, a Continuous Memory DTC 524/543 may have been set without a Continuous Memory DTC 556/557, even though a fault has occurred in the fuel pump primary circuit. Go to X115 to check the fuel pump primary circuit. X115 - Continuous Code 556/557: Check EEC-IV Harness