DTC P0231: Fuel Pump Relay: Condition

Fuel pump primary circuit has been indicated. Possible causes are as follows:

KOEO & KOER DTC P0231

If engine starts, replace PCM and repeat quick test. See QUICK TEST in TESTS W/CODES - INTRODUCTION article. If engine does not start, go to next step.

Check B+ To Fuel Pump Relay

Turn ignition off. Disconnect fuel pump relay wiring harness connector. Turn ignition on. Measure voltage between chassis ground and IGN START/RUN terminal at fuel pump relay wiring harness connector. Measure voltage between chassis ground and B+ terminal at fuel pump relay wiring harness connector. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, check circuit fuse. If fuse is okay, repair open in B+ circuit and repeat quick test. See QUICK TEST in TESTS W/CODES - INTRODUCTION article.

Check POWER-TO-PUMP Circuit Resistance

Leave ignition off and fuel pump relay disconnected. Measure resistance between negative battery terminal and POWER-TO-PUMP terminal at fuel pump relay wiring harness connector. If resistance is less than 10 ohms, replace fuel pump relay and repeat quick test. See QUICK TEST in TESTS W/CODES - INTRODUCTION article. If resistance is 10 ohms or more, repair open in POWER-TO-PUMP circuit and repeat quick test.

Continuous Memory DTC P0231

Turn ignition off. Disconnect PCM wiring harness connector. Inspect pins for damage and repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Connect jumper wire between test pins No. 77 (PWR GND) and 80 (FP). Connect DVOM between test pins No. 40 (FPM) and 51 (GND). Voltage should be 10 volts or more. Observe DVOM for indication of fault while wiggling and bending B+ circuit to fuel pump relay. Fault will be indicated by sudden change in DVOM voltage. Wiggle and bend POWER-TO-PUMP circuit between fuel pump relay and FPM circuit splice. Lightly tap on fuel pump relay. Check connectors for clean tight connection. If any faults are found, isolate and repair as necessary. If no faults are found, fault cannot be duplicated at this time. Go to DIAGNOSTIC TEST Z (INTERMITTENT) .