J20 - Does Engine Start

Diagnostic Trouble Code (DTC) 543 indicates a fuel pump secondary circuit failure between the B(+) supply and the Fuel Pump Monitor (FPM) connection to the power-to-pump circuit.

Possible causes:

No Start:

- Open circuit between the B(+) supply and the FPM connection to the power-to-pump circuit.

- Fuel pump relay contacts always open.

Engine Starts:

- Heated Oxygen Sensor (HO2S) short to power (dual HO2S applications).

- Damaged Powertrain Control Module (PCM).

- Does the engine start?

Yes -- Replace PCM. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)

No -- Go to J21. J21 - Check For B(+) to Fuel Pump Relay