Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 26 other vehicles, including the 1999 Mercury Tracer, 1999 Mercury Sable, 1999 Mercury Mystique, 1999 Mercury Mountaineer, and 1999 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.
Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:
- Fuel pump relay.
- Inertia Fuel Shutoff (IFS) switch.
- Wiring harness circuits (B+, FP, FPM, GND, FP PWR and VPWR).
- Powertrain Control Module (PCM).
- 1) KOEO & KOER DTC P0230
This DTC indicates a fuel pump primary circuit failure. Possible causes are:- Open or shorted circuit.
- Faulty fuel pump relay.
- Faulty PCM.
Disconnect fuel pump relay connector. Relay is located in engine compartment power distribution box or fuse/relay box. Turn ignition on. Measure voltage between VPWR terminal at fuel pump relay connector and chassis ground. See Fig 1-Fig 4 . If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in VPWR circuit between PCM power relay and fuel pump relay.
Courtesy of FORD MOTOR CO.
Fig 2: Identifying Fuel System Circuits & Connector Terminals (Explorer, Mountaineer, Ranger, Sable, Taurus, Town Car & Windstar)Courtesy of FORD MOTOR CO.
Fig 3: Identifying Fuel System Circuits (Crown Victoria, Econoline, Expedition, Grand Marquis, Navigator & Pickup - F150 Except Lightning & F250 Light Duty)Courtesy of FORD MOTOR CO.
Courtesy of FORD MOTOR CO.
- 2) Check Fuel Pump Relay
Turn ignition off. On fuel pump relays that terminals are numbered 1-5, measure resistance between relay terminal No. 1 and all other relay terminals. Resistance should be 40-120 ohms between terminals No. 1 and 2 and more than 10,000 ohms between terminal No.1 and other relay terminals. On fuel pump relays that terminals are numbered 30, 85, 86, 87 and 87A, measure resistance between relay terminal No. 85 and all other relay terminals. Resistance should be 40-120 ohms between terminals No. 85 and 86 and more than 10,000 ohms between terminal No.85 and other relay terminals. On both relays, if resistance is not as specified replace relay. If resistance is as specified, go to next step. - 3) Check Fuel Pump Circuit
Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Turn ignition on. Measure voltage between PCM connector pin No. 80 (No. 54 on Contour 2.5L, Cougar 2.5L and Mystique 2.5L) and chassis 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. - 4) Check FP Circuit For Short To Ground
Turn ignition off. Disconnect scan tool from Data Link Connector (DLC). Measure resistance between PCM connector pin No. 80 (No. 54 on Contour 2.5L, Cougar 2.5L and Mystique 2.5L) and chassis ground. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground in FP circuit. - 5) Check For Open FP Circuit
Measure resistance of FP circuit between FP terminal at fuel pump relay wiring harness connector and PCM connector pin No. 80 (No. 54 on Contour 2.5L, Cougar 2.5L and Mystique 2.5L). If resistance is less than 5 ohms and DTC P0231 or P0232 is also present with DTC P0230, go to next step. If resistance is less than 5 ohms and DTC P0231 or P0232 is not present with DTC P0230, replace PCM. If resistance is 5 ohms or more, repair open in FP circuit. - 6) Check Fuel Pump Circuit Inside PCM
Reconnect PCM connector and fuel pump relay. Connect scan tool to DLC. Turn ignition on. Using scan tool, select FPF PID. If PID value indicates YES, a fault exists inside of PCM. Replace PCM. If PID value indicates NO, go to next step. - 7) Check PCM Fuel Pump Primary Circuit
Ensure battery is fully charged. To perform this step, ensure scan tool is connected to a power source that is powered with key in START position. While cranking engine, observe FPF PID value. If PID value indicates YES during cranking, replace PCM. If PID value indicates NO during cranking, fuel pump primary circuit is okay. If DTC P0231 is present, go to step 20). If DTC P0232 is present, go to step 10).NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 7) to step 10). No test procedures have been omitted. - 10) KOEO & KOER DTC P0232
This DTC indicates that PCM detected high FPM circuit voltage when fuel pump was commanded off. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step 65) (Pickup - F150 Lightning) or go to step 15) (all other models). - 11) Verify Fuel Pump
Turn ignition on and wait 5 seconds. Listen for operational noise from fuel pump. If fuel pump can be heard, go to next step. If fuel pump cannot be heard, go to step 13). - 12) Check Fuel Pump Relay
Turn ignition off. Disconnect fuel pump relay. Turn ignition on. Listen for operational noise from fuel pump. If fuel pump operates, repair short to power in FP PWR or FPM circuit. If fuel pump still does not operate, replace fuel pump relay. - 13) Check For Open FPM Circuit
Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between PCM connector pin No. 40 and FP PWR terminal at fuel pump relay wiring harness connector. See Fig 1-Fig 4 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in FPM circuit. - 14) Check PCM Fuel Pump Circuit
Reconnect PCM connector and fuel pump relay. Turn ignition on. Using scan tool, select FPM PID. If PID value indicates ON, replace PCM. If PID value indicates ON, fuel pump primary circuit is okay. On Pickup F150 - Lightning and "F" Super-Duty models, go to step 55). On all other models, no problem is indicated at this time. Testing is complete. Disregard DTC P0232 at this time. Repeat QUICK TEST . - 15) Check IFS Switch
Turn ignition off. Disconnect Inertia Fuel Shutoff (IFS) switch connector. Ensure IFS switch is reset. Measure resistance between IFS switch terminals "C" and NC (power circuit to fuel pump). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, replace IFS switch. - 16) Check For Open FP PWR Circuit
Disconnect fuel pump relay. Measure resistance of FP PWR circuit between fuel pump relay wiring harness connector and IFS switch wiring harness connector. If resistance is less than 5 ohms, reconnect fuel pump relay and go to next step. If resistance is 5 ohms or more, repair open in FP PWR circuit. - 17) Check For Open Fuel Pump Ground Circuit
Disconnect fuel pump connector. Measure resistance between fuel pump ground circuit at fuel pump wiring harness connector and chassis ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in fuel pump ground circuit. - 18) Check For Open FP PWR Circuit
Measure resistance of FP PWR circuit between fuel pump wiring harness connector and IFS switch wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in FP PWR circuit. - 19) Check Fuel Pump Resistance
Measure resistance between FP PWR terminal and ground terminal at fuel pump. If resistance is 10 ohms or more, replace fuel pump. If resistance is less than 10 ohms, fuel pump circuits are okay. Testing is complete. Disregard DTC P0232 at this time. Repeat QUICK TEST . - 20) KOEO & KOER DTC P0231
This DTC indicates a fuel pump secondary circuit failure. Attempt to start engine. If engine starts, replace PCM. If engine does not start, go to next step. - 21) Check B+ To Fuel Pump Relay
Turn ignition off. Disconnect fuel pump relay. Measure voltage between chassis ground and B+ terminal at fuel pump relay wiring harness connector. If voltage is more than 10.5 volts, go to step 23) (Pickup - F150 Lightning) or go to next step (all other models). If voltage is 10.5 volts or less, check condition of related fuses/fuse links. If fuse/fuse links are blown, check for short to ground. Repair as necessary. If fuse/fuse links are okay, repair open in B+ circuit. - 22) Check FP PWR Circuit Resistance
Measure resistance between FP PWR terminal at fuel pump relay wiring harness connector and negative battery terminal. If resistance is less than 10 ohms, replace fuel pump relay. If resistance is 10 ohms or more, repair open in FP PWR circuit. - 23) Check For Open VPWR Circuit (Pickup - F150 Lightning)
Disconnect IFS switch relay. Turn ignition on. Measure voltage between VPWR terminal and IFS terminal at IFS switch relay wiring harness connector. If voltage is more than 10.5 volts, go to step 28). If voltage is 10.5 volts or less, go to next step. - 24) Check For Power To IFS Switch Relay
Measure voltage between VPWR terminal at IFS switch relay wiring harness connector and chassis ground. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open VPWR circuit between power relay and IFS switch relay. - 25) Check Ground Circuit To IFS Switch
Disconnect Inertia Fuel Shutoff (IFS) switch connector. Ensure IFS switch is reset. Measure resistance of ground circuit between IFS switch wiring harness connector and chassis ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ground circuit. - 26) Check IFS Switch
Measure resistance between IFS switch terminals "C" and NC (ground circuit to IFS switch relay). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, replace IFS switch. - 27) Check For Open In IFS Circuit
Measure resistance of IFS circuit between IFS switch wiring harness connector and IFS switch relay wiring harness connector. If resistance is 5 ohms or more, repair open in IFS circuit. If resistance is less than 5 ohms, no fault is indicated. Disregard DTC P0232 at this time. Repeat QUICK TEST . - 28) Check FP PWR Circuit Resistance
Measure resistance of FP PWR circuit between fuel pump relay wiring harness connector and IFS switch relay wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in FP PWR circuit. - 29) Check Relays
Connect a jumper wire between positive battery terminal and terminal No. 86 at IFS switch relay. Connect another jumper wire between negative battery terminal and terminal No. 85 at IFS switch relay. With relay energized, measure resistance between terminals No. 30 and 87 at IFS switch relay. Resistance should be less than 5 ohms. Repeat test for fuel pump relay. Replace relay(s) as necessary. If relays are okay, repair open in FP PWR circuit between FPM splice and IFS switch relay. See Fig 4. - 30) Continuous Memory DTC P0232
If DTC P0230 is also present, go to step 40). If DTC P0232 is only DTC present, turn ignition on. Using scan tool, select FPM PID. Observe PID value for indication of fault while wiggling and bending FP PWR circuit between fuel pump relay and fuel pump. Fault will be indicated by FPM PID value changing to ON (indicating a short to power). Wiggle and bend FPM circuit between PCM and FP PWR circuit splice. Wiggle and bend fuel pump ground circuit. Lightly tap on fuel pump, IFS switch and fuel pump relay to simulate road shock. Check connectors for clean tight connection. If no faults are found, fault cannot be duplicated at this time. Go to TEST Z . If any fault is found, proceed as follows:- On all models except Pickup - F150 Lightning and Pickup Super-Duty models, isolate fault and repair as necessary.
- On Pickup - F150 Lightning and "F" Super-Duty models, disconnect low speed fuel pump relay and note FPM PID value. If FPM PID consistently indicates ON, check fuel pump relay ground circuit resistor. See Fig 4 or Fig 5 . Replace resistor as necessary. If resistor is okay, repair open circuit between low speed fuel pump relay and wiring harness splice. If FPM PID indicates OFF, isolate fault found performing wiggle test and repair as necessary.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 30) to step 35). No test procedures have been omitted. - 35) Continuous Memory DTC P0231
This DTC indicates that sometime during vehicle operation when fuel pump was commanded on, FPM circuit voltage was low. Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Connect a jumper wire between PCM connector pin No. 80 (No. 54 on Contour 2.5L, Cougar 2.5L and Mystique 2.5L). Turn ignition on. Connect DVOM between PCM connector pin No. 40 and chassis ground. Voltage should be more than 10 volts. Observe DVOM for indication of fault while wiggling and bending B+ circuit to fuel pump relay. Fault will be indicated by sudden change in DVOM voltage. Wiggle and bend B+ circuit to fuel pump relay. Wiggle and bend FP PWR circuit between fuel pump relay and FPM circuit splice. Lightly tap on fuel pump relay to simulate road shock. Check connectors for clean tight connection. If any faults are found, isolate fault and repair as necessary. If no faults are found, fault 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 35) to step 40). No test procedures have been omitted. - 40) Continuous Memory DTC P0230
This DTC indicates a fuel pump primary circuit fault. Turn ignition on and wait 5 seconds. Using scan tool, select FPF PID. PID value should indicate NO. Observe PID value for indication of fault while wiggling and bending FUEL PUMP (FP) circuit between fuel pump relay and PCM. Fault will be indicated by FPF PID indicating YES. Wiggle and bend VPWR circuit between fuel pump relay and PCM power relay. Lightly tap on fuel pump relay to simulate road shock. Check connectors for clean tight connection. If any faults are found, isolate and repair as necessary. If no faults are found, fault 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 40) to step 45). No test procedures have been omitted. - 45) KOEO Or KOER DTC P1232: Check Voltage To Low Speed Fuel Pump Relay
This DTC indicates a low speed fuel pump primary circuit fault. Turn ignition off. Disconnect low speed fuel pump relay. Turn ignition on. Measure voltage between VPWR terminal at low speed fuel pump relay wiring harness and ground. See Fig 4 or Fig 5 . If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in VPWR circuit between PCM power relay and low speed fuel pump relay. - 46) Check Low Speed Fuel Pump Relay
Turn ignition off. Measure resistance between terminal No. 85 and all other relay terminals. Resistance between relay terminals No.85 and 86 should be 40-85 ohms. Resistance between relay terminal No. 85 and all other terminals should be more than 10,000 ohms. If resistance is not as specified, replace low speed fuel pump relay. If resistance is as specified, go to next step. - 47) Check Low Fuel Pump (LFP) Circuit
Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Turn ignition on. Measure voltage between LFP terminal at low speed fuel pump wiring harness connector and chassis ground. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in LFP circuit. - 48) Check LFP Circuit For Short To Ground
Turn ignition off. Disconnect scan tool from Data Link Connector (DLC). Measure resistance between LFP terminal at low speed fuel pump wiring harness connector and chassis ground. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground in LFP circuit. - 49) Check For Open LFP Circuit
Measure resistance between PCM connector pin No. 19 and LFP terminal at low speed fuel pump wiring harness connector. If resistance is less than 5 ohms, replace PCM. If resistance is 5 ohms or more, repair open in LFP circuit.NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 49) to step 55). No test procedures have been omitted. - 55) Check For Open Fuel Pump Ground Circuit
Turn ignition off. Disconnect low speed fuel pump relay. Turn ignition on. Using scan tool, select FPM PID. If PID value indicates OFF, no fault is indicated at this time. Disregard DTC P1232 at this time. Repeat QUICK TEST . If PID value indicates ON, check fuel pump relay ground circuit resistor. See Fig 4 or Fig 5 . Replace resistor as necessary. If resistor is okay, repair open circuit between low speed fuel pump relay and wiring harness splice.NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 55) to step 60). No test procedures have been omitted. - 60) Continuous Memory DTC P1232
This DTC indicates a low speed fuel pump primary circuit fault. Turn ignition on and wait 5 seconds. Using scan tool, select LFPF PID. PID value should indicate NO. Observe PID value for indication of fault while wiggling and bending LPF circuit between low speed fuel pump relay and terminal No. 19 at PCM. Fault will be indicated by LFPF PID indicating YES. Wiggle and bend VPWR circuit between low speed fuel pump relay and PCM power relay. Lightly tap on low speed fuel pump relay to simulate road shock. Check connectors for clean tight connection. If any faults are found, isolate fault and repair as necessary. If no faults are found, fault 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 60) to step 65). No test procedures have been omitted. - 65) Check Fuel Pump Ground Circuit Resistance (Pickup - F150 Lightning)
Turn ignition off. Disconnect low speed fuel pump relay. Measure resistance between ground terminal at low speed fuel pump relay wiring harness connector and chassis ground. See Fig 4. If resistance is less than 7 ohms, go to next step. If resistance is 7 ohms or more, check fuel pump relay ground circuit resistor. Replace resistor as necessary. If resistor is okay, repair open in ground circuit. - 66) Check For Open In Ground Circuit
Disconnect fuel pump connectors. Measure resistance of ground circuit between low speed fuel pump relay wiring harness connector and fuel pump wiring harness connector. Repeat resistance check for ground circuit in other fuel pump wiring harness. If both resistance readings are less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, repair open in ground circuit. - 67) Check Fuel Pump Resistance
Measure resistance between fuel pump terminals. Resistance should be less than 10 ohms. Repeat resistance check for other fuel pump. Replace fuel pump(s) as necessary. If both fuel pumps are okay, go to next step. - 68) Check For Open In FP PWR Circuit
Disconnect Inertia Fuel Shutoff (IFS) switch relay connector. Measure resistance of FP PWR circuit between IFS switch relay wiring harness connector and fuel pump wiring harness connector. Repeat resistance check for other fuel pump. If both resistance readings are less than 5 ohms, no fault is indicated. Disregard DTC P0232 at this time. Repeat QUICK TEST . If any resistance reading is 5 ohms or more, repair open in FP PWR circuit.NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 68) to step 70). No test procedures have been omitted. - 70) Hard Start/Lacks Power
Turn ignition off. Disconnect low speed fuel pump relay connector. Measure resistance of ground circuit between low speed fuel pump relay wiring harness connector and chassis ground. See Fig 4 or Fig 5 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ground circuit. - 71) Check Ground Circuit Through Resistor
Measure resistance of fuel pump ground circuit (through resistor) between low speed fuel pump relay wiring harness connector and chassis ground. See Fig 6. If resistance is less than 7 ohms, go to next step. If resistance is 7 ohms or more, repair open circuit between low speed fuel pump relay and ground. Ensure ground circuit resistor is okay. Repair as necessary. - 72) Check Fuel Pump Relay
Measure resistance between relay terminals No. 30 and 87A. Terminal numbers are molded on relay. If resistance is less than ohms, no problem is indicated at this time. If symptom still exists, go to TROUBLE SHOOTING - NO CODES - EEC-V article. If resistance is 5 ohms or more, replace relay.NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 72) to step 75). No test procedures have been omitted. - 75) Check PID Values
Turn ignition on and check for fuel pump noise. If fuel pump operational noise can be heard within one second of turning ignition on, go to TEST A and continue testing. If fuel pump noise is not heard, turn ignition off. Using scan tool, select FPF and FPM PIDs from PID/DATA monitor menu. If scan tool is only capable of viewing one PID at a time, compete test for each PID. Turn ignition on and wait one second. If FPF PID value indicates NO and FPM PID value indicates OFF, go to next step. If FPF PID indicates YES, go to TEST KA, step 1) and continue testing. If FPM PID indicates ON, go to TEST KA, step 10) and continue testing. - 76) Check PIDs While Cranking Engine
Ensure battery is fully charged. To perform this step, ensure scan tool is connected to a power source that is powered with key in START position. While cranking engine, observe FPF and FPM PID values. If FPF PID value indicates NO and FPM PID value indicates ON, fuel pump circuits are okay. If symptom still exists, go to TROUBLE SHOOTING - NO CODES - EEC-V article. If FPF PID value indicates YES during cranking, go to TEST KA, step 1) and continue testing. If FPM PID value indicates OFF during cranking, go to TEST KA, step 20) and continue testing for DTC P0231.
NOTE:
To identify fuel pump relay terminals, refer to numbers molded on relay. Two different numbered relays are used. Fuel pump relay terminals may be numbered 1-5 or terminals may be numbered 30, 85, 86, 87 and 87A. On relays that are numbered 1-5, terminals for relay coil are terminals No. 1 and 2. On relays that are numbered 30, 85, 86, 872 and 87A, terminals for relay coil are terminals No. 85 and 86.
NOTE:
To identify IFS switch relay terminals, refer to numbers molded on relay.
NOTE:
To identify fuel pump relay terminals, refer to numbers molded on relay.
NOTE:
Applications sent to this step do not have any fuel pump related KOEO DTCs present. The following test steps will determine if fuel pump circuits are a cause of no-start.