2005 Mercury Mariner 3.0 1, FWDFACTORY OEM SERVICE PROCEDURE

DTC P1234: Fuel Pump Driver Module Disabled or Off Line

P1234 - FUEL PUMP DRIVER MODULE DISABLED OR OFF LINE

Description:  The powertrain control module (PCM) monitors the fuel pump monitor 2 (FPM2) circuit from the fuel pump driver module 2 (FPDM2). With the key on, the FPDM2 continuously sends a duty cycle signal to the PCM through the FPM2 circuit. The test fails if the PCM stops receiving the duty cycle signal.
Possible Causes: 
  • Inertia fuel shutoff (IFS) switch needs to be reset
  • Open FPDM2 ground circuit
  • Open circuit to FPDM2 PWR RLY
  • Open FPDM2 PWR circuit
  • Open or shorted FPM2 circuit (engine should start)
  • Damaged IFS switch
  • Damaged FPDM2 PWR RLY
  • Damaged FPDM2
Diagnostic Aids:  The PCM expects to see one of the following duty cycle signals from the FPDM2 on the FPM2 circuit: 1) 50% (500 ms on, 500 ms off), all OK. 2) 25% (250 ms on, 750 ms off), the FPDM2 did not receive a fuel pump (FP) duty cycle command from the PCM, or the duty cycle that was received was invalid. 3) 75% (750 ms on, 250 off), the FPDM2 has detected a concern in the circuits between the FPDM2 and the fuel pump.
Application  Key On Engine Off  Key On Engine Running  Continuous Memory 
All GO to KB: Fuel Pump Driver Module STEP KB55.
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