DTC P1237: Fuel Pump Secondary Circuit Malfunction

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2005 Mercury Sable, 2005 Mercury Mountaineer, 2005 Mercury Monterey, 2005 Mercury Montego, and 2005 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.

P1237 - FUEL PUMP SECONDARY CIRCUIT MALFUNCTION

Description:	NOTE: For LS and Thunderbird, the FPDM functions are incorporated in the rear electronics module (REM). Also, the REM does not use an FPM circuit. Diagnostic information is sent on the communication link. This DTC indicates that the fuel pump driver module (FPDM) detected a fuel pump secondary circuit concern. The FPDM sends a message to the powertrain control module (PCM) through the fuel pump monitor (FPM) circuit indicating this concern was detected. The PCM sets the DTC when the message is received.
Possible Causes:	Open or shorted FP PWR circuit Open FP RTN circuit to FPDM Open or shorted circuit in the fuel pump Locked fuel pump rotor Damaged FPDM For LS and Thunderbird, circuits associated with the fuel pump relay
Diagnostic Aids:	The FPDM sends a 75% duty cycle (750 ms on, 250 ms off) through the FPM circuit to the PCM while the concern is being detected by the FPDM. If the concern is no longer detected, the PCM returns to sending an all OK (50% duty cycle) message to the PCM. The FPDM controls pump speed by supplying a variable ground on the FP RTN circuit.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
All	GO to KB: Fuel Pump Driver Module STEP KB31.