Diagnostic Aids

WARNING: This page is about a different car, the 1995 Ford Ranger. 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+, FUEL PUMP, FPM, POWER-TO-PUMP and VPWR).
Powertrain Control Module (PCM).

Fig 1: Fuel System Test Circuit & Connector Terminal ID (Ranger)

1) DTC P0230

Fuel pump primary circuit has been indicated. Possible causes are as follows:

Open or shorted circuit.
Faulty fuel pump relay.
Faulty PCM.

Disconnect fuel pump relay wiring harness connector. Turn ignition on. Measure voltage between VPWR terminal at connector and chassis ground. If 10.5 volts or more are present, go to next step. If less than 10.5 volts are present, repair open in VPWR circuit between EEC power relay and fuel pump relay.

2) Check Fuel Pump Relay

Turn ignition off. Leave fuel pump relay disconnected. Measure resistance between terminals No. 85 and 86 at fuel pump relay. See Fig 2. Resistance should be 40-85 ohms. Measure resistance between terminal No. 85 and terminals No. 30 and 87 at fuel pump relay. Resistance should be more than 10,000 ohms. If resistance is as specified, go to next step. If resistance is not as specified, replace fuel pump relay.

Fig 2: Identifying Fuel Pump Relay Terminals (Ranger)

3) Check Fuel Pump Circuit

Leave ignition off and fuel pump relay disconnected. Disconnect PCM wiring harness connector. Inspect pins for damage and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 80 and chassis ground. If voltage is one volt or less, go to next step. If voltage is more than one volt, repair short to power in FUEL PUMP circuit and repeat QUICK TEST.

4) Leave ignition off and fuel pump relay disconnected. Disconnect scan tester from Data Link Connector (DLC). Measure resistance between test pin No. 80 and test pins No. 51, 91 and 103. If each resistance measurement is more than 10,000 ohms, go to next step. If any resistance measurement is 10,000 ohms or less, repair short circuit and repeat QUICK TEST.

5) Leave ignition off and fuel pump relay disconnected. Measure resistance between FUEL PUMP terminal at fuel pump relay wiring harness connector and test pin No. 80 at breakout box. If resistance is less than 5 ohms, replace PCM and repeat QUICK TEST. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 10). No test procedures have been omitted.

10) DTC P0232

If engine starts, go to next step. If engine does not start, go to step 15).

11) Check Fuel Pump

Turn ignition on. 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 FPM or POWER-TO-PUMP circuit and repeat QUICK TEST. If fuel pump still does not operate, replace fuel pump relay and repeat QUICK TEST.

13) Check FPM Circuit

Turn ignition off. Leave fuel pump relay disconnected. Disconnect PCM wiring harness connector. Inspect pins for damage and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure resistance between test pin No. 40 and POWER-TO-PUMP circuit at fuel pump relay wiring harness connector. If resistance is less than 5 ohms, replace PCM and repeat QUICK TEST. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 15). No test procedures have been omitted.

15) Check IFS Switch

Turn ignition off. Locate IFS switch in trunk near left hinge. Measure resistance between terminals "C" and NC of IFS switch. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, reset or replace IFS switch and repeat QUICK TEST.

16) Leave IFS switch disconnected. Turn ignition on. Measure voltage between terminal POWER-TO-PUMP terminal and ground. If voltage is less than 5 volts, repair open in POWER-TO-PUMP circuit and repeat QUICK TEST. If voltage is 5 volts or more, check fuel pump and fuel pump ground circuit. Repair or replace as necessary.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 16) to step 20). No test procedures have been omitted.

20) DTC P0231

If engine starts, replace PCM and repeat QUICK TEST. If engine does not start, go to next step.

21) Check B+ To Fuel Pump Relay

Turn ignition off. Disconnect fuel pump relay wiring harness connector. Measure voltage between chassis ground and B+ terminal at wiring harness connector. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, check circuit fuse. If fuse is okay, repair open in B+ circuit and repeat QUICK TEST.

22) Check POWER-TO-PUMP Circuit Continuity

Leave ignition off and fuel pump relay disconnected. Measure resistance between negative battery terminal and POWER-TO-PUMP terminal at wiring harness connector. If resistance is less than 10 ohms, replace fuel pump relay and repeat QUICK TEST. If resistance is 10 ohms or more, repair open in POWER-TO-PUMP circuit and repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 30). No test procedures have been omitted.

30) Continuous Memory DTC P0232

Turn ignition off. Connect scan tester to Data Link Connector (DLC). Using scan tester, access FRM PID. Observe PID for indication of fault while wiggling and bending POWER-TO-PUMP circuit between fuel pump relay and fuel pump. Fault will be indicated by FPM PID turning on. Wiggle and bend FPM circuit between PCM and POWER-TO-PUMP circuit splice. Wiggle and bend fuel pump ground circuit. 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 CIRCUIT TEST Z.

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

Turn ignition off. Disconnect PCM wiring harness connector. Inspect pins for damage and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Connect DVOM between test pins No. 40 (FPM) and 51 (GND). Voltage should be 10 volts or more. 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 POWER-TO-PUMP circuit between fuel pump relay and FPM circuit splice. Lightly tap on fuel pump relay. 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 CIRCUIT 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

Turn ignition off. Connect scan tester to Data Link Connector (DLC). Using scan tester, access FPA PID. Observe PID for indication of fault while wiggling and bending FUEL PUMP circuit between fuel pump relay and PCM. Fault will be indicated by FPA PID turning on. Wiggle and bend FPM circuit between PCM and POWER-TO-PUMP circuit splice. Wiggle and bend VPWR circuit between fuel pump relay and EEC-V power relay. 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 CIRCUIT TEST Z.