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Home >> Ford >> 2000 >> Excursion 7.3 F, 4WD >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - EEC-V - CNG, Flex-Fuel & Gasoline >> System Tests >> Test Kb: Fuel Pump Driver Module >> Diagnostic Aids

Diagnostic Aids

NOTE: After each service or repair procedure has been completed, reconnect all components. Clear DTCs and repeat QUICK TEST  procedures to ensure all EEC-V systems are working properly and DTCs are no longer present.
NOTE: Fuel pump relay may also be referred to as FPDM power supply relay.

Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:

Fig 1: Identifying Fuel Pump Driver Module Circuits & Connector Terminals (Continental)
G99H02639Courtesy of FORD MOTOR CO.
Fig 2: Identifying Fuel Pump Driver Module Circuits & Connector Terminals (Contour, Cougar, Focus, Mystique, Sable & Taurus)
G00013296Courtesy of FORD MOTOR CO.
Fig 3: Identifying Fuel Pump Driver Module Circuits & Connector Terminals (Escort)
G99J02640Courtesy of FORD MOTOR CO.
Fig 4: Identifying Fuel Pump Driver Module Circuits & Connector Terminals (LS)
G00013297Courtesy of FORD MOTOR CO.
Fig 5: Identifying Fuel Pump Driver Module Circuits & Connector Terminals (Mustang)
G99B02641Courtesy of FORD MOTOR CO.
    NOTE: DTC P1233 and P1234 are identical, except DTC P1234 will not illuminate Malfunction Indicator Lamp (MIL). On LS models, these DTCs indicate PCM is not receiving fuel level information on Standard Corporate Protocol (SCP) network from Rear Electronics Module (REM). See MODULE COMMUNICATIONS NETWORK - LS article in ACCESSORIES & EQUIPMENT for complete DTC listing and test procedures.

  1. 1) DTC P1233 Or P1234
    These DTCs indicate PCM has stopped receiving duty cycle signal from Fuel Pump Driver Module (FPDM), also referred to as fuel tank unit. Possible causes are:
    • Inertia Fuel Shutoff (IFS) Switch Needs To Be Reset
    • Open FPDM Ground Circuit
    • Open Or Shorted FPM Circuit
    • Faulty IFS Switch
    • Faulty FPDM
    • Faulty PCM
    • Open VPWR Circuit To FPDM (Continental)
    • Open FPDM PWR Circuit; Or Open B+ Circuit To Constant Control Relay Module (CCRM) (Escort & Mustang)
    • Faulty CCRM (Escort & Mustang)
    • Open Ground Circuit To CCRM (Mustang)

    If DTC P1233 or P1234 is present in KOEO ON-DEMAND SELF-TEST, go to next step. If DTC P1233 or P1234 is not present in KOEO ON-DEMAND SELF-TEST, PCM is now receiving a signal from FPDM. Fault code may have been set due to Inertia Fuel Shutoff (IFS) switch being tripped, then reset. If engine starts, go to step  25). If engine is a no-start, disregard DTCs P1233 and P1234 at this time and repeat QUICK TEST . If any other DTCs are present, perform appropriate system test and repair as necessary. After repairing the engine no-start condition, go to step  25) to diagnose intermittent causes of DTC P1233 or P1234.

  2. 2) Check If Engine Starts

    Attempt to start engine. If engine starts, go to step  15). If engine does not start, verify IFS switch is set (button depressed) and go to next step.

  3. 3) Check Power & Ground Circuits To FPDM

    Turn ignition switch to OFF position. Disconnect FPDM connector. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Using a DVOM, measure voltage between FPDM harness connector FPDM PWR circuit terminal (VPWR circuit terminal on Continental) and ground circuit terminal. See Fig 1-Fig 3, and Fig 5 . FPDM PWR or VPWR is the power circuit coming from the IFS switch to the FPDM. If voltage is more than 10.5 volts, replace FPDM. If voltage is 10.5 volts or less, go to next step.

  4. 4) Check Power To FPDM

    Turn ignition switch to ON position. Using a DVOM, measure voltage between ground and FPDM harness connector FPDM PWR circuit terminal (VPWR terminal on Continental). FPDM may also referred to as fuel tank unit. If voltage is more than 10.5 volts, repair open ground circuit to FPDM. If voltage is 10.5 volts or less, go to next step (Escort and Mustang), go to step  14) (Continental), or go to step  8) (all others).

  5. 5) Check B+ Voltage To CCRM (Escort & Mustang)

    Turn ignition switch to OFF position. Disconnect CCRM connector. On Mustang, CCRM is mounted on a bracket behind engine coolant reservoir. On Escort, CCRM is located in left front of engine compartment. On all models, measure voltage between terminal No. 11 at CCRM harness connector and ground. See Fig 3 or Fig 5 and Fig 6 . If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, check condition of related fuse. If fuse is blown, check for short to ground in B+ or FPDM PWR circuit. FPDM may also referred to as fuel tank unit. See WIRING DIAGRAMS article. Repair as necessary. If fuse is okay, repair open in B+ circuit.
    Fig 6: Identifying Constant Control Relay Module Connector Terminals
    G99D02642Courtesy of FORD MOTOR CO.

  6. 6) Check Fuel Pump Relay Ground Circuit To CCRM

    Using a DVOM, measure resistance of ground circuit between ground and CCRM harness connector terminal No. 15 (Escort) or No. 18 (Mustang). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ground circuit.

  7. 7) Check For Open FPDM PWR Circuit

    Using a DVOM, measure resistance of FPDM PWR circuit between CCRM harness connector terminal No. 5 and FPDM harness connector terminal No. 2 (Escort) or No. 9 (Mustang). FPDM may also referred to as fuel tank unit. If resistance is less than 5 ohms, replace CCRM. If resistance is 5 ohms or more, FPDM PWR circuit is open. Go to step  13) to isolate fault.

  8. 8) Check For B+ Voltage To Fuel Pump Relay (Contour, Cougar, Focus & Mystique)

    Disconnect fuel pump relay. Using a DVOM, measure voltage of B+ circuit between ground and fuel pump relay cavity No. 3. See Fig 2 and Fig 7 . If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, check for blown 15-amp B+ circuit fuse No. 9 (Contour, Cougar & Mystique), or No. 12 (Focus) located in battery junction box in engine compartment. If fuse is okay, repair open B+ circuit. If fuse is blown, check B+ or FPDM PWR circuit for short to ground. FPDM may also referred to as fuel tank unit.
    Fig 7: Identifying ISO Micro Relay Cavity Terminals
    G98B00332Courtesy of FORD MOTOR CO.

  9. 9) Check For Ground To FPDM Power Supply Relay

    Turn ignition switch to OFF position. Disconnect scan tool from DLC. Using a DVOM, measure resistance of ground circuit between fuel pump relay cavity No. 2 in battery junction box and negative battery terminal. See Fig 2 and Fig 7 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ground circuit.

  10. 10) Check For Open FPDM PWR Circuit

    Using a DVOM, measure resistance of FPDM power circuit between fuel pump relay cavity No. 5 and FPDM harness connector terminal No. 9. See Fig 7 and Fig 8 . FPDM may also referred to as fuel tank unit. If resistance is less than 5 ohms, reconnect FPDM and go to next step. If resistance is 5 ohms or more, FPDM circuit is open. Go to step  13) to isolate fault.
    Fig 8: Identifying Fuel Pump Driver Module Connector Terminals
    G96E30274Courtesy of FORD MOTOR CO.

  11. 11) Check VPWR Circuit Voltage To Fuel Pump Relay

    Turn ignition switch to ON position. Using a DVOM, measure VPWR circuit voltage between ground and fuel pump relay cavity No. 1. See Fig 7. If voltage is more than 10.5 volts, replace fuel pump relay. If voltage is 10.5 volts or less, repair open in VPWR circuit. See WIRING DIAGRAMS article.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 11) to step 13). No test procedures have been omitted.

  12. 13) Isolate Open In FPDM PWR Circuit

    Disconnect Inertia Fuel Shutoff (IFS) switch connector. On Escort and Mustang, measure resistance of FPDM PWR circuit between IFS switch harness connector and CCRM harness connector terminal No. 5. FPDM may also referred to as fuel tank unit. On Contour, Cougar, Focus and Mystique, measure resistance of FPDM PWR circuit between IFS switch harness connector and fuel pump relay cavity No. 5. See Fig 6 or Fig 7 . On all models, measure resistance of FPDM PWR circuit between FPDM harness connector terminal No. 9 and IFS switch harness connector. See Fig 8. If both resistance measurements are less than 5 ohms, verify IFS switch is set (button depressed). If IFS switch is set, replace IFS switch. If either resistance measurement is 5 ohms or more, repair open in appropriate FPDM PWR circuit.
    13. NOTE: PCM power relay is also referred to as EEC-V power relay.

  13. 14) Isolate Open In VPWR Circuit To FPDM (Continental)
    Turn ignition switch to OFF position. Disconnect PCM power relay. Disconnect Inertia Fuel Shutoff (IFS) switch. Using a DVOM, measure resistance of VPWR circuit between PCM power relay cavity No. 87 and IFS switch harness connector. See Figure. Measure resistance of VPWR circuit between FPDM harness connector terminal No. 9 and IFS switch harness connector. FPDM may also referred to as fuel tank unit. See Fig 8. If both resistance measurements are less than 5 ohms, verify IFS switch is set (button depressed). If IFS switch is set, replace IFS switch. If either resistance measurement is more than 5 ohms, repair open in appropriate VPWR circuit.

  14. 15) Check For Open FPM Circuit

    Turn ignition switch to OFF position. Disconnect FPDM connector. FPDM may also referred to as fuel tank unit. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of FPM circuit between PCM harness connector terminal No. 40 and FPDM harness connector terminal No. 4 (Escort), or No. 7 (all others). See Figure and Fig 8 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in FPM circuit.

  15. 16) Check FPM Circuit For Short To Power In Harness

    Turn ignition switch to ON position. Measure voltage between PCM connector terminal No. 40 and ground. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in FPM circuit.

  16. 17) Check FPM Circuit For Short To Ground In Harness

    Turn ignition switch to OFF position. Disconnect scan tool. Measure resistance between PCM connector terminal No. 40 and ground. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in FPM circuit.
    17. NOTE: In the following test step, it is normal for voltage to cycle less than .02 volt and return to .02-1.0 volt.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 18) to step 25). No test procedures have been omitted.

  17. 18) Check For FPM Output From FPDM
    Reconnect FPDM connector. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Measure voltage between PCM connector terminals No. 40 and 51. If voltage is .02-1.0 volt, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE . If voltage is not .02-1.0 volt, replace FPDM.
    18. NOTE: With no fault detected, FPDM will send a 50 percent duty cycle signal on FPM circuit to PCM. FPM PID value should display 50 percent. Depending on scan tool being used, some scan tools will display a random value between 85-115 percent.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 30). No test procedures have been omitted.

  18. 25) Check VPWR Circuit For Loss Of Power, & FPM Circuit To FPDM For Intermittent Short Or Open
    Turn ignition switch to ON position. Using scan tool, select FPM PID from PID/DATA MONITOR & RECORD menu. Observe FPM PID value for indication of fault while performing the following. Fault will be indicated if FPM PID value changes from 50 percent, or value stops fluctuating:
    • Wiggle and bend all FPDM system related wiring harnesses and connectors. FPDM may also referred to as fuel tank unit.
    • On Escort and Mustang, wiggle and bend B+ circuit to terminal No. 11 at CCRM.
    • On Mustang, wiggle and bend ground circuit to terminal No. 18 at CCRM.
    • On Focus, Contour, Cougar, Mystique, Taurus and Sable wiggle and bend B+ and ground circuits to FPDM power supply relay.
    • On all models, wiggle and bend FPM circuit between PCM and FPDM.
    • Lightly tap on IFS switch, CCRM, FPDM and FPDM power supply relay to simulate road shock.

    If any faults are found, isolate fault and repair as necessary. If no faults are found, problem cannot be duplicated at this time. Go to TEST Z .

    19. NOTE: DTC P1235 and P1236 are identical, except DTC P1236 will not illuminate Malfunction Indicator Lamp (MIL). On LS models, FPDM functions are incorporated in Rear Electronics Module (REM). In the following steps, if directed to perform an FPDM action, complete the action using REM. See Fig 1-Fig 5 .

  19. 30) DTC P1235 Or P1236: Check For These DTC To Be Present In KOEO Or KOER On-Demand Self-Tests
    These DTCs indicate that FPDM, also referred to as fuel tank unit has detected an invalid or missing FP circuit signal from PCM. FPDM will send a message to PCM through FPM circuit, indicating failure has been detected. PCM will set the DTC when message has been received. Possible causes are:
    • Open Or Shorted FP Circuit
    • Faulty FPDM
    • Faulty PCM

    If DTC P1235 or P1236 is present in KOEO ON-DEMAND SELF-TEST or KOER ON-DEMAND SELF-TEST, DTC is a hard fault. Go to next step. If DTC P1235 or P1236 is not present in KOEO ON-DEMAND SELF-TEST or KOER ON-DEMAND SELF-TEST, fault is intermittent. On LS, go to step  42). On all other models, go to step  45).

  20. 31) Check For Open FP Circuit Between FPDM & PCM

    Turn ignition switch to OFF position. Disconnect FPDM connector. FPDM may also referred to as fuel tank unit. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance of FP circuit between PCM connector and FPDM harness connector. See Fig 1-Fig 5 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in FP circuit.

  21. 32) Check FP Circuit For Short To Power In Harness

    Turn ignition switch to ON position. Measure voltage between PCM connector FP terminal and ground. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in FP circuit.

  22. 33) Check For Short To Ground In Harness

    Turn ignition switch to OFF position. Disconnect scan tool from DLC. Measure resistance between PCM connector FP terminal and ground. If resistance is more than 10 k/ohms, go to step  36) (LS), or go to next step (all other models). If resistance is 10 k/ohms or less, repair short to ground in FP circuit.

  23. 34) Check FP Circuit In FPDM

    Reconnect FPDM. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Using a DVOM, measure voltage between PCM harness connector terminals No. 51 (PWR GND) and No. 80 (FP). If voltage is 4.5-5.5 volts, replace PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE . If voltage is not 4.5-5.5 volts, replace FPDM.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 34) to step 36). No test procedures have been omitted.

  24. 36) Check FPF PID

    Turn ignition switch to ON position. Using scan tool, select FPF PID from PID/DATA MONITOR & RECORD menu. Observe FPF PID for 20 seconds. If FPF PID indicated YES during 20 second time period, go to step  40). If FPF PID did not indicated YES during 20 second time period, go to next step.

  25. 37) Check FP PID

    Select FP PID from PID/DATA MONITOR & RECORD menu. If FP PID indicates 70-80 percent, go to next step. If FP PID does not indicate 70-80 percent, cycle ignition switch to OFF, then to ON position. Repeat step  36). If result is YES, go to step  40). If result is NO, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE .
    26. NOTE: PWM_DC1 PID indicates signal sent to REM from PCM on FP circuit.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 38) to step 40). No test procedures have been omitted.

  26. 38) Access REM PIDs & Check PWM_DC1 PID
    Select PWM_DC1 PID from REM menu. If PWM_DC1 PID indicates 70-80 percent, turn ignition switch to OFF position. No fault is indicated, disregard DTC P1235 or P1236 at this time and diagnose problem by symptom. See SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V (GASOLINE) article. If PWM_DC1 PID does not indicate 70-80 percent, replace REM.

  27. 40) Check REM Harness Voltage On FP Circuit At PCM

    Turn ignition switch to OFF position. Disconnect PCM connector "A". See Figure. Turn ignition switch to ON position. Measure voltage between PCM connector terminal A58 and ground. If voltage is more than 8 volts, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE . If voltage is 8 volts or less, replace REM. See MODULE COMMUNICATIONS NETWORK - LS article in ACCESSORIES & EQUIPMENT.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 40) to step 42). No test procedures have been omitted.
    28. NOTE: PWM_DC1 PID indicates signal sent to REM from PCM on FP circuit.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 42) to step 45). No test procedures have been omitted.

  28. 42) Check FP Circuit For Intermittent Problems
    Turn ignition switch to ON position. Using scan tool, select PWM_DC1 PID from REM menu. Observe PWM_DC1 PID value for indication of fault while wiggling and bending FP circuit between REM and PCM. Fault will be indicated if PWM_DC1 PID value changes. If any faults are found, isolate fault and repair as necessary. If no faults are found, problem cannot be duplicated at this time. Go to TEST Z .

  29. 45) Check FP Circuit For Intermittent Open Or Shorted Circuit

    Turn ignition switch to ON position. Using scan tool, select FPM PID from PID/DATA MONITOR & RECORD menu. Observe FPM PID value for indication of fault while wiggling and bending FP circuit between FPDM and PCM. FPDM may also referred to as fuel tank unit. Lightly tap on FPDM to simulate road shock. Fault will be indicated if FPM PID value changes from 50 percent, or value stops fluctuating. If any faults are found, isolate fault and repair as necessary. If no faults are found, problem cannot be duplicated at this time. Go to TEST Z .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 45) to step 47). No test procedures have been omitted.

  30. 47) DTC P1237, P1238 Or P1641

    These DTCs indicate FPDM, also referred to as Fuel Tank Unit has detected a fuel pump secondary circuit fault. This is due to an intermittent or hard fault. If DTC P1237, P1238 or P1641 is present in KOEO ON-DEMAND SELF-TEST or KOER ON-DEMAND SELF-TEST, DTC is a hard fault. Go to next step. If DTC P1237, P1238 or P1641 is not present in KOEO ON-DEMAND SELF-TEST or KOER ON-DEMAND SELF-TEST, fault is intermittent. On LS, go to step  67). On all other models, go to step  56).

  31. 48) Check If Engine Starts

    Attempt to start engine. If engine starts, go to step  80) (LS), or go to step  60) (all other models). If engine does not start, go to step  61) (LS), or go to next step (all other models) to diagnose fuel pump secondary circuits.
    32. NOTE: If directed here from step  61), FPDM functions are incorporated in Rear Electronics Module (REM). FPDM may also referred to as fuel tank unit. If directed to perform an FPDM action, complete the action using REM. See Fig 4 for module terminal assignments.

  32. 49) Check FP PWR, FP RTN & Internal Fuel Pump Circuit Resistance
    Turn ignition switch to OFF position. Disconnect scan tool from DLC. Disconnect FPDM connector. FPDM may also referred to as fuel tank unit. Measure resistance between FP PWR terminal and FP RTN terminal at FPDM harness connector. See Fig 1-Fig 5 . If resistance is 10 ohms or more, an open in secondary circuit exists. Go to step  54). If resistance is less than 10 ohms, go to next step.

  33. 50) Check FP RTN Circuit For Short To Power In Harness

    Turn ignition switch to ON position. Using a DVOM, measure voltage of FP RTN circuit between FPDM harness connector and ground. FPDM may also referred to as fuel tank unit. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to VPWR.

  34. 51) Check FP PWR Circuit For Short To Ground In Harness

    Turn ignition switch to OFF position. Disconnect fuel pump connector. Using a DVOM, measure resistance of FP PWR circuit between FPDM harness connector and ground. FPDM may also referred to as fuel tank unit. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in FP PWR circuit.
    35. NOTE: To perform step  52) without scan tool, fuel pump can be commanded on for one second by cycling ignition switch from OFF to ON position and repeating as necessary.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 52) to step 54). No test procedures have been omitted.

  35. 52) Check For Power To Fuel Pump
    Reconnect FPDM and scan tool. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Connect DVOM between fuel pump harness connector FP PWR and FP RTN terminals. Using scan tool, access OUTPUT TEST MODE. See OUTPUT TEST MODE  under ADDITIONAL SYSTEM FUNCTIONS. Command OUTPUTS ON. Fuel pump should turn on for about 5 seconds. With fuel pump commanded ON, if voltage is more than 10 volts, replace fuel pump. If voltage is 10 volts or less, verify battery is full charged. Ensure fuel pump command ON time did not time-out before voltage check was made. If battery is okay and command ON time did not time-out, replace FPDM.

  36. 54) Isolate Open Circuit

    Turn ignition switch to OFF position. Disconnect fuel pump. Measure resistance of FP PWR and FP RTN circuits between fuel pump harness connector and FPDM harness connector. FPDM may also referred to as fuel tank unit. See Fig 1-Fig 5 . Measure internal resistance of fuel pump. If all resistance readings are less than 10 ohms, no fault is indicated at this time. Verify results of previous steps. If any resistance reading is 10 ohms or more, repair open in appropriate circuit or replace fuel pump.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 54) to step 56). No test procedures have been omitted.

  37. 56) Check For Intermittent DTC P1237 Or P1238

    Turn ignition switch to ON position. Using scan tool, select FPM PID. If FPM PID value is 75 percent or varies within a range of 250-400 percent, a hard fault is present, go to step  48). If FPM PID value is not 75 percent or varies within a range of 250-400 percent, DTC is intermittent, go to next step.
    38. NOTE: With no fault detected, FPDM will send a 50 percent duty cycle signal on FPM circuit to PCM. FPM PID value should display 50 percent. Depending on scan tool being used, some scan tools will display a random value between 85-115 percent.

  38. 57) Check Fuel Pump Secondary Circuits For Intermittent Open Or Short
    Turn ignition switch to ON position. Using scan tool, select FPM PID from PID/DATA MONITOR & RECORD menu. Observe FPM PID value for indication of fault while wiggling and bending FP PWR and FP RTN circuits between FPDM and fuel pump. FPDM may also referred to as fuel tank unit. Lightly tap on FPDM to simulate road shock. Fault will be indicated if FPM PID value changes from 50 percent, or varies within a range of 85-115 percent. If any faults are found, isolate fault and repair as necessary. If no faults are found, go to next step.

  39. 58) Check FP PWR Circuit For Short To Ground

    Turn ignition switch to OFF position. Disconnect FPDM. FPDM may also referred to as fuel tank unit. Connect a test light between FP PWR terminal and FPDM PWR terminal at FPDM harness connector. Turn ignition switch to ON position. Observe test light for indication of fault while wiggling and bending FP PWR circuit between FPDM and fuel pump. If a fault is indicated, test light will turn on. If any faults are found, isolate fault and repair as necessary. If no faults are found, unable to duplicate or identify fault at this time. Go to TEST Z .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 58) to step 60). No test procedures have been omitted.

  40. 60) Check FP RTN Circuit For Short To Ground

    Ensure ignition switch is turned to ON position. Using a DVOM, measure voltage between FPDM harness connector FPDM PWR circuit and FP RTN circuit terminals. FPDM may also referred to as fuel tank unit. If voltage is less than one volt, replace FPDM. If voltage is one volt or more, repair short to ground in FP RTN circuit.

  41. 61) Check REM/FP PWR & Ground Circuit To REM Harness Connector J1 (LS)

    Ensure Inertia Fuel Shutoff (IFS) switch is not tripped. Disconnect REM connector J1. See Fig 4. Turn ignition switch to ON position. Using a DVOM, measure voltage between REM harness connector J1 terminals No. 1 (FP PWR) and No. 2 (GND). If voltage is 10.5 volts or less, go to next step. If voltage is more than 10.5 volts, go to step  49).

  42. 62) Check REM/FP PWR Circuit Voltage To REM

    Ensure ignition switch is turned to ON position. Using a DVOM, measure voltage between ground and REM harness connector J1 terminal No. 1 (FP PWR). If voltage is more than 10.5 volts, repair open ground circuit from REM harness connector J1 terminal No. 2. If voltage is 10.5 volts or less, go to next step.

  43. 63) Check For B+ Voltage To Fuel Pump Relay

    Turn ignition switch to OFF position. Remove fuel pump relay from battery junction box in engine compartment. Using a DVOM, measure voltage between ground and fuel pump relay cavity No. 3. See Fig 4. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, check for blown fuse No. 417 (15-amp) located in battery junction box. If fuse is blown, check for short to ground in B+ circuit or short to voltage in FP RTN circuit before replacing fuse. If fuse is okay, repair open in Red/Blue wire between fuse No. 417 and fuel pump relay cavity No. 3.

  44. 64) Check For IGN START/RUN Voltage (Through IFS Switch) To Fuel Pump Relay

    Turn ignition switch to OFF position. Disconnect REM connector J3. Turn ignition switch to ON position. Using a DVOM, measure voltage of IGN START/RUN circuit between ground and REM harness connector J3 terminal No. 8 (Green/White wire). If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, check for blown fuse No. 204 (5-amp) in central junction box located behind right kick panel. If fuse is blown, check for short to ground in IGN START/RUN circuit before replacing fuse. If fuse is okay, go to step  69) to isolate open circuit.

  45. 65) Check Ground Circuit To Fuel Pump Relay

    Turn ignition switch to OFF position. Using a DVOM, measure resistance of ground circuit between fuel pump relay cavity No. 1 and ground. See Fig 4. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ground circuit.

  46. 66) Check REM/FP PWR Circuit Continuity

    Using a DVOM, measure resistance of REM/FP PWR circuit between fuel pump relay cavity No. 5 and REM harness connector terminal No. 1. See Fig 4. If resistance is less than 5 ohms, replace fuel pump relay. If resistance is 5 ohms or more, repair open in REM/FP PWR circuit.

  47. 67) Check REM/FP PWR, REM GND & Related Fuel Pump Relay Circuits For Intermittents

    Turn ignition switch to OFF position. Disconnect REM connector J1 if not previously disconnected. See Fig 4. Connect test light between REM connector J1 terminals No. 1 (REM/FP PWR) and No. 2 (GND). Turn ignition switch to ON position. Observe test light for indication of fault while wiggling and bending REM/FP PWR circuit and GND circuits to REM. Shake, wiggle and bend GND, IGN START/RUN and B+ circuits to fuel pump relay. Lightly tap on fuel pump relay and IFS switch to simulate road shock. If a fault is indicated, test light will turn off. If any faults are found, isolate fault and repair as necessary. If no faults are found, go to next step.

  48. 68) Check FP PWR & FP RTN Circuits For Intermittent Problems

    Turn ignition switch to OFF position. Using a DVOM, measure resistance between REM connector J1 terminals No. 11 (FP PWR) and No. 12 (FP RTN). Observe DVOM for indication of fault while wiggling and bending FP PWR and FP RTN circuits between REM and fuel pump. Perform same procedure with DVOM connected between REM connector J1 terminal No. 12 (FP RTN) and ground. A fault is indicated when resistance changes suddenly. If any faults are found, isolate fault and repair as necessary. If no faults are found, problem cannot be identified at this time. Turn ignition switch to OFF position. Remove DVOM, reconnect REM and go to TEST Z .

  49. 69) Locating Open in IGN START/RUN Circuit

    Disconnect IFS switch. Using a DVOM, measure resistance between IFS switch terminals. Record resistance reading. Also, measure resistance of IGN START/RUN circuit between fuel pump relay cavity No. 2 and IFS. If both resistance measurements are less than 5 ohms, repair open in IGN START/RUN circuit between fuse No. 204 (5-amp) in central junction box and IFS switch. If resistance is 5 ohms or more in either measurement, replace IFS switch or repair open in IGN START/RUN circuit between fuel pump relay cavity No. 2 and IFS. Ensure fuel pump motor diode is okay. See WIRING DIAGRAMS article.
    50. NOTE: Diagnostic steps  70)- 76) are performed when directed here from TEST HC, step  2).

  50. 70) Check Battery Voltage With Outputs Commanded On
    Turn ignition switch to OFF position. Disconnect fuel pump connector. Connect scan tool to DLC. Turn ignition switch to ON position. Connect a DVOM between battery terminals. Using scan tool, access OUTPUT TEST MODE. See OUTPUT TEST MODE  under ADDITIONAL SYSTEM FUNCTIONS. While monitoring battery voltage, command OUTPUTS ON. Record voltage measurement within 5 seconds. If battery voltage is more than 11 volts, command OUTPUTS OFF and go to next step. If battery voltage is 11 volts or less, battery voltage is low. Service battery/charging system as necessary. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.

  51. 71) Check Ground Circuit To Fuel Pump

    Turn ignition switch to OFF position. Connect DVOM between fuel pump harness connector FP PWR circuit terminal and negative battery terminal. See Fig 1-Fig 5 . Turn ignition switch to ON position. Using scan tool, command OUTPUTS ON. Record voltage measurement within 5 seconds. If voltage is 10.5 volts or less, ground circuit to fuel pump is okay. Go to next step. If voltage is more than 10.5 volts, locate and repair high resistance in ground circuit to fuel pump. Check all wiring and connectors for fuel pump and FPDM (REM on LS) for corrosion or damage. FPDM may also referred to as fuel tank unit. Check FPDM (REM on LS) ground connection to chassis ground. Repair as necessary.

  52. 72) Check Voltage To FPDM

    Turn ignition switch to OFF position. Disconnect FPDM connector. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Measure voltage between negative battery terminal and FPDM PWR terminal (VPWR terminal on Continental) at FPDM harness connector. See Fig 1-Fig 5 . If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts, or less, go to step .

    Turn ignition switch to OFF position and proceed as follows:

    • Continental

      Disconnect FPDM connector. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Using a DVOM, measure voltage of VPWR circuit between negative battery terminal and FPDM harness connector terminal No. 9. See Fig 1 and Fig 8 . If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts, or less, insufficient voltage is being supplied to FPDM. Go to step  75).

    • LS

      Disconnect REM connector. Turn ignition switch to ON position. Using a DVOM, measure voltage of REM/FP PWR circuit between negative battery terminal and REM harness connector J1 terminal No. 1. See Fig 4. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts, or less, insufficient voltage is being supplied to REM. Go to step  75).

    • Except Continental & LS

      Disconnect FPDM connector. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Using a DVOM, measure voltage of FPDM PWR circuit between negative battery terminal and FPDM harness connector. See Fig 2, Fig 3 or Fig 5 . If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts, or less, insufficient voltage is being supplied to FPDM. Go to step  75).

  53. 73) Check FP PWR Circuit

    Turn ignition switch to OFF position and proceed as follows:

    • Continental

      Connect a jumper wire between FPDM harness connector VPWR circuit and FP PWR circuit terminals. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and fuel pump harness connector FP PWR terminal. If voltage is more than 10.5 volts, and is within .5 volt of voltage measured in step  72), turn ignition switch to OFF position and remove jumper. Ensure all previous test step results are correct. If results are correct, replace FPDM. If voltage is not as specified, isolate high resistance in FP PWR circuit and repair as necessary.

    • Contour, Cougar, Focus & Mystique

      Connect a jumper wire between FPDM harness connector FPDM PWR circuit and FP PWR circuit terminals. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and fuel pump harness connector FP PWR terminal. If voltage is more than 10.5 volts and is within .5 volt of voltage measured in step  72), turn ignition switch to OFF position and remove jumper. Ensure all previous test step results are correct. If results are correct, replace FPDM. If voltage is not as specified, isolate high resistance in FP PWR circuit and repair as necessary.

    • Escort & Mustang

      Connect a jumper wire between FPDM harness connector FPDM PWR circuit and FP PWR circuit terminals. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and fuel pump harness connector FP PWR terminal. If voltage is more than 10.5 volts, and is within .5 volt of voltage measured in step  72), turn ignition switch to OFF position and remove jumper. Ensure all previous test step results are correct. If results are correct, replace FPDM. If voltage is not as specified, isolate high resistance in FP PWR circuit and repair as necessary.

    • LS

      Connect a jumper wire between FPDM harness connector REM/FP PWR circuit and FP PWR circuit terminals. FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and fuel pump harness connector FP PWR terminal. If voltage is more than 10.5 volts and is within .5 volt of voltage measured in step  72), turn ignition switch to OFF position and remove jumper. Ensure all previous test step results are correct. If results are correct, replace REM. If voltage is not as specified, isolate high resistance in FP PWR circuit and repair as necessary.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 73) to step 75). No test procedures have been omitted.

  54. 75) Check For B+ Voltage To PCM Power Relay, CCRM, Or Fuel Pump Relay

    Turn ignition switch to OFF position and proceed as follows:

    • Continental

      Remove PCM power relay. Relay is located in battery junction box in engine compartment, above left wheelwell. Turn ignition switch to ON position. Using a DVOM, measure voltage of B+ circuit between negative battery terminal and PCM power relay cavity No. 30. See Figure. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, insufficient voltage is being supplied to PCM power relay. Check all related wiring and connectors to PCM power relay for corrosion or damage. Repair as necessary.

    • Contour, Cougar, Focus & Mystique

      Remove fuel pump relay. Relay is located in battery junction box in left rear corner of engine compartment. Turn ignition switch to ON position. Using a DVOM, measure voltage of B+ circuit between negative battery terminal and fuel pump relay cavity No. 3. See Fig 7. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, insufficient voltage is being supplied to fuel pump relay. Check all related wiring and connectors on B+ circuit to fuel pump relay for corrosion or damage. Repair as necessary.

    • Escort & Mustang

      Disconnect Constant Control Relay Module (CCRM). On Mustang, CCRM is mounted on a bracket behind engine coolant reservoir. On Escort, CCRM is located in left front of engine compartment. On all models, turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and CCRM harness connector terminal No. 11 (B+). See Fig 6. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, insufficient voltage is being supplied to CCRM. Check all related wiring and connectors to CCRM for corrosion or damage. Repair as necessary.

    • LS

      Remove fuel pump relay. Relay is located in battery junction box on left side of luggage compartment. Turn ignition switch to ON position. Using a DVOM, measure voltage of B+ circuit between negative battery terminal and fuel pump relay cavity No. 3. See Fig 7. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, insufficient voltage is being supplied to fuel pump relay. Check all related wiring and connectors on B+ circuit to fuel pump relay for corrosion or damage. Repair as necessary.

  55. 76) Check FPDM PWR Circuit

    Turn ignition switch to OFF position and proceed as follows:

    • Continental

      Connect a jumper wire between PCM power relay cavities No. 30 (B+) and No. 87 (VPWR). Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and FPDM harness connector terminal No. 9. FPDM may also referred to as fuel tank unit. If voltage is more than 10.5 volts, ensure all previous test step results are correct. If results are correct, replace FPDM. If voltage is 10.5 volts or less, check for high resistance in VPWR circuit from PCM power relay to IFS switch, and/or from IFS switch to FPDM. If circuits are okay, check IFS switch for proper function. Repair as necessary.

    • Contour, Cougar, Focus & Mystique

      Connect a jumper wire between fuel pump relay cavities No. 3 (B+) and No. 5 (FPDM PWR). FPDM may also referred to as fuel tank unit. Using a DVOM, measure voltage of FPDM PWR circuit between negative battery terminal and FPDM harness connector. If voltage is more than 10.5 volts, ensure all previous test step results are correct. If results are correct, replace FPDM. If voltage is 10.5 volts or less, isolate high resistance in system circuits and repair as necessary.

    • Escort & Mustang

      Connect a jumper wire between CCRM harness connector terminals No. 11 (B+) and No. 5 (FPDM PWR). FPDM may also referred to as fuel tank unit. Turn ignition switch to ON position. Using a DVOM, measure voltage of FPDM PWR circuit between negative battery terminal and FPDM harness connector. If voltage is more than 10.5 volts, ensure all previous test step results are correct. If results are correct, replace FPDM. If voltage is 10.5 volts or less, isolate high resistance in system circuits and repair as necessary.

    • LS

      Connect a jumper wire between fuel pump relay cavities No. 3 (B+) and No. 5 (REM/FP PWR). Using a DVOM, measure voltage of REM FP PWR circuit between negative battery terminal and REM harness connector terminal No. 1. If voltage is more than 10.5 volts, ensure all previous test step results are correct. If results are correct, replace REM. If voltage is 10.5 volts or less, isolate high resistance in system circuits and repair as necessary.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 76) to step 80). No test procedures have been omitted.

  56. 80) Check FP RTN Circuit For Short To Ground

    Turn ignition switch to OFF position. Disconnect REM connector J1. See Fig 4. Turn ignition switch to ON position. Measure voltage between REM harness connector J1 terminals No. 1 (FP PWR) and No. 12 (FP RTN). If voltage is less than one volt, go to step  67). If voltage in one volt or more, repair short to ground.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 80) to step 85). No test procedures have been omitted.
    57. NOTE: Diagnostic steps  85)- 86) are performed when directed here from SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V (GASOLINE) article.

  57. 85) Perform REM Self-Test To Verify IFS Switch Input To REM
    Using scan tool, perform Self-Test on Rear Electronics Module (REM). If DTC B2172 is present, go to next step. If DTC B2172 is not present, go to TEST A, step  1).

  58. 86) B2172: Check IFS Switch Input Circuit To REM

    Turn ignition switch to OFF position. Disconnect REM connector J3. See Fig 4. Turn ignition switch to ON position. Using a DVOM, measure voltage of IFS INPUT circuit between ground and REM harness connector J3 terminal No. 8. If voltage is 10.5 volts or less, turn ignition switch to OFF position and ensure IFS switch is not open. If IFS switch is okay, repair open circuit between IFS switch and REM harness connector. If voltage is more than 10.5 volts, perform the following:
    • If engine is a no-start and REM DTC B2172 was received in On-Demand Self-Test mode, replace REM. See MODULE COMMUNICATIONS NETWORK - LS article in ACCESSORIES & EQUIPMENT.
    • If engine will start or REM DTC B2172 is a Continuous Memory DTC, DTC is intermittent. If engine is a no-start, return to SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V (GASOLINE) article to continue diagnosis. If engine will start, go to TEST Z .
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