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HOMESERVICE MANUALSFORD2004MUSTANG BASE, 2D COUPE, 3.9 6, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 2546 (ENGINE CONTROLS - PINPOINT TEST JB: SECONDARY IGNITION (COP) THROUGH PINPOINT TEST KF: FAN CONTROL (FC) RELAYS - (EXCEPT DIESEL & HYBRID))PINPOINT TEST KB: FUEL PUMP DRIVER MODULE (FPDM)TEST PROCEDURES
2004 Ford Mustang Base, 2D Coupe, 3.9 6, Automatic

Test Procedures

2004 Ford Mustang Base, 2D Coupe, 3.9 6, AutomaticSECTION Test Procedures
WARNING: This page does not describe the selected car, but rather 28 other vehicles, including the 2011 Mercury Milan, 2011 Mercury Mariner, 2011 Mercury Grand Marquis, 2011 Lincoln Town Car, and 2011 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.
  1. KB1 CHECK FOR DIAGNOSTIC TROUBLE CODES (DTCS) 

    Are DTCs P1233, P1235, or P1237 present? 

    Yes No
    For DTC P1233, GO to  KB2.
    For DTC P1235, GO to  KB16.
    For DTC P1237, GO to  KB22.    		 For all others, GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .
  2. KB2 DTC P1233: IS DTC P1233 PRESENT IN THE KOEO SELF-TEST? 
    • Carry out the PCM self-test.

    Is DTC P1233 present? 

    Yes No
    GO to  KB3. For a no start (engine cranks), DISREGARD the DTC at this time. RETURN to Symptom Charts and continue as directed. After repairing the no start, DIAGNOSE the intermittent causes of P1233,
    GO to  KB15.
    For all others, GO to  KB15.
  3. KB3 DOES THE ENGINE START? 

    Does the engine start? 

    Yes No
    GO to  KB11. VERIFY the IFS switch is set (button pressed). If OK,
    GO to  KB4.
  4. KB4 CHECK THE VOLTAGE AND GROUND CIRCUITS TO THE FPDM 
    • FPDM connector disconnected.
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      VOLTAGE REFERENCE CHART

      (+) FPDM Connector, Harness Side (-) FPDM Connector, Harness Side
      VPWR Fuel - Pin 5 PWRGND - Pin 3

    Is the voltage grater than 10 ohms? 

    Yes No
    GO to  KB11. GO to  KB5.
  5. KB5 CHECK THE VOLTAGE TO THE FPDM 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      VOLTAGE REFERENCE CHART

      (+) FPDM Connector, Harness Side (-)
      VPWR Fuel - Pin 5 Ground

    Is the voltage greater than 10 V? 

    Yes No
    REPAIR the open circuit. The FPDM ground circuit is open.
    Clear the PCM DTCs. REPEAT the self-test.    		 GO to  KB6.
  6. KB6 CHECK THE B+ VOLTAGE TO THE FPDM POWER SUPPLY RELAY 
    • Ignition OFF.
    • FPDM PWR Relay connector disconnected.
    • Measure the voltage between:
      VOLTAGE REFERENCE CHART

      (+) FPDM PWR Relay Connector, Harness Side (-)
      B+ Ground

    Is the voltage greater than 10 V? 

    Yes No
    GO to  KB7. A B+ circuit concern is present. CHECK the condition of the related fuse/fuse links. If OK, REPAIR the open circuit. If the fuse/fuse link is damaged, CHECK the circuit for a short to ground before installing a new fuse/fuse link.
    Clear the PCM DTCs. REPEAT the self-test.
  7. KB7 CHECK THE VPWR VOLTAGE TO THE FPDM POWER SUPPLY RELAY 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      VOLTAGE REFERENCE CHART

      (+) FPDM PWR Relay Connector, Harness Side (-)
      VPWR Ground

    Is the voltage greater than 10 ohms? 

    Yes No
    GO to  KB8. REPAIR the open circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  8. KB8 CHECK FOR GROUND TO THE FPDM POWER SUPPLY RELAY 
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) FPDM PWR Relay Connector, Harness Side (-)
      GND Ground

    Is the resistance less than 5 ohms? 

    Yes No
    GO to  KB9. REPAIR the open circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  9. KB9 CHECK THE VPWR FUEL CIRCUIT FOR AN OPEN CIRCUIT IN THE HARNESS 
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) FPDM Connector, Harness Side (-) FPDM PWR Relay Connector, Harness Side
      VPWR Fuel - Pin 5 VPWR Fuel

    Is the resistance less than 5 ohms? 

    Yes No
    INSTALL a new FPDM relay. Clear the PCM DTCs. REPEAT the self-test. GO to  KB10.
  10. KB10 ISOLATE THE OPEN IN THE FPDM CIRCUIT 
    • IFS Switch connector disconnected.
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) FPDM Connector, Harness Side (-) IFS Switch Connector, Harness Side
      VPWR Fuel - Pin 5 VPWR Fuel - B - Pin 1
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) FPDM PWR Relay Connector, Harness Side (-) IFS Switch Connector, Harness Side
      VPWR Fuel VPWR Fuel - A - Pin 2

    Is the resistance less than 5 ohms? 

    Yes No
    INSTALL a new IFS switch. REFER to the appropriate Fuel Tank and Lines article. VERIFY the IFS switch is set (button pressed).
    Clear the PCM DTCs. REPEAT the self-test.    		 REPAIR the open circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  11. KB11 CHECK THE FPM CIRCUIT FOR AN OPEN CIRCUIT IN THE HARNESS 
    • FPDM connector disconnected.
    • PCM connector disconnected.
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) FPDM Connector, Harness Side (-) PCM Connector, Harness Side
      FPM - Pin 1 FPM - Pin B21

    Is the resistance less than 5 ohms? 

    Yes No
    GO to  KB12. REPAIR the open circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  12. KB12 CHECK THE FPM CIRCUIT FOR A SHORT TO POWER IN THE HARNESS 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      VOLTAGE REFERENCE CHART

      (+) FPDM Connector, Harness Side (-)
      FPM - Pin 1 Ground

    Is the voltage less than 1 V? 

    Yes No
    GO to  KB13. REPAIR the short circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  13. KB13 CHECK THE FPM CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS 
    • Ignition OFF.
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) FPDM Connector, Harness Side (-)
      FPM - Pin 1 Ground

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  KB14. REPAIR the short circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  14. KB14 CHECK FOR FPM OUTPUT FROM THE FPDM 
    NOTE: It is OK for the voltage to cycle below this range and then return within range.
    • FPDM connector connected.
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      VOLTAGE REFERENCE CHART

      (+) PCM Connector, Harness Side (-)
      FPM - Pin B21 Ground

    Is the voltage between 0.02-1 V? 

    Yes No
    GO to  KB34. INSTALL a new FPDM.
    REFER to the appropriate Fuel Charging and Controls article.
    Clear the PCM DTCs. REPEAT the self-test.
  15. KB15 CHECK THE CIRCUITS THAT MAY CAUSE AN INTERMITTENT LOSS OF VOLTAGE TO THE FPDM 
    NOTE: Be aware that P1233 could be set if the IFS switch is tripped then reset.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.