X88 - Check B+ to Low Speed Fuel Pump Relay

NOTE: If Key On Engine Off Diagnostic Trouble Code (DTC) 543 is also present, go to X90. X90 - Does Engine Start

DTC 524 indicates a Low Speed Fuel Pump (LFP) secondary circuit failure.

Possible causes (without DTC 543):
- Open B(+) circuit to LFP relay.
- Open power-to-pump circuit between LFP relay and splice to "common" power-to-pump circuit.
- Damaged fuel pump dropping resistor.
- Damaged LFP relay.

- Key "OFF".

- Disconnect LFP relay.

- Measure voltage between B(+) circuit at the LFP relay vehicle harness connector and the battery negative post.

- Is voltage greater than 10.5 volts?

Yes -- Go to X89. X89 - Check Power to Pump Circuit Continuity

No -- Verify condition of related fuses. If OK, service open in B(+) circuit to LFP relay. Reconnect LFP relay. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)