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Home >> Mercury >> 2009 >> Mariner Base, 2.5 7, AWD >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Powertrain DTC Charts & Descriptions (Except Diesel & Hybrid) >> DTC Diagnosis >> DTC P1237: - Fuel Pump Secondary Circuit

DTC P1237: - Fuel Pump Secondary Circuit

DTC P1237: - FUEL PUMP SECONDARY CIRCUIT

Description:  This DTC indicates 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 short FP PWR circuit
  • Open FP RTN circuit to FPDM
  • Open or short circuit in the fuel pump
  • Locked fuel pump rotor
  • Damaged FPDM
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 Pinpoint Test KB .
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