P0231: Fuel Pump Secondary Circuit Low

WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2004 Mercury Sable, 2004 Mercury Mountaineer, 2004 Mercury Monterey, 2004 Mercury Marauder, and 2004 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.

P0231 - FUEL PUMP SECONDARY CIRCUIT LOW

Description:	NOTE: For natural gas applications, the following description applies to the fuel shutoff valve monitor (FSVM) and the fuel shutoff valve power (FSV PWR) circuits. The PCM monitors the fuel pump monitor (FPM) circuit. The test fails if the PCM commands the fuel pump ON and B+ voltage is not detected on the FPM circuit.
Possible Causes:	Open B+ circuit to the fuel pump relay. Open FP PWR circuit between the fuel pump relay and its connection to the FPM circuit. Damaged fuel pump relay. Damaged PCM (engine does start). For 5.4L SC Lightning, damaged IFS switch, IFS switch relay, or concern with related circuits.
Diagnostic Aids:	During the KOEO self-test, the PCM commands the fuel pump on so this test can be performed.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
Dedicated NGV	GO to PINPOINT TEST KC: FUEL SHUTOFF VALVE RELAY Step 18.	GO to PINPOINT TEST KC: FUEL SHUTOFF VALVE RELAY Step 18.	GO to PINPOINT TEST KC: FUEL SHUTOFF VALVE RELAY Step 24.
F-Super Duty, Excursion, Expedition, Navigator	GO to PINPOINT TEST KA: FUEL PUMP RELAY Step 80.	GO to PINPOINT TEST KA: FUEL PUMP RELAY Step 80.	GO to PINPOINT TEST KA: FUEL PUMP RELAY Step 85.
All others	GO to PINPOINT TEST KA: FUEL PUMP RELAY Step 23.	GO to PINPOINT TEST KA: FUEL PUMP RELAY Step 23.	GO to PINPOINT TEST KA: FUEL PUMP RELAY Step 39.