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Diagnostic Aids

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: Typical Fuel Pump Relay Schematic
G96I01008
Fig 2: Fuel System Test Circuit & Connector Terminals
G96D01015
  1. Step 1) KOEO & KOER DTC P0230  Fuel pump primary circuit has been indicated. Possible causes are as follows:
    • Open or shorted circuit.
    • Faulty fuel pump relay.
    • Faulty PCM.

    For Continuous Memory DTC P0230, go to step 40). 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. Step 2) Check Fuel Pump Relay  Turn ignition off. Leave fuel pump relay disconnected. Measure resistance as follows:
    • For ISO relays, between terminals No. 85 and 86 at fuel pump relay.
    • For all other relays, between FUEL PUMP and VPWR terminals at fuel pump relay.

    Replace fuel pump relay if resistance is not 40-120 ohms. If resistance is okay, measure resistance as follows:

    • For ISO relays, between terminals No. 30 and 87 at fuel pump relay.
    • All other relays, between FUEL PUMP CIRCUIT terminal and B+ and POWER-TO-PUMP terminal individually at fuel pump relay.

    Replace fuel pump relay if resistance is not 10,000 ohms. If resistance is okay, go to next step.

    Fig 3: ISO Type Fuel Pump Relay Terminals
    G96B01019
    Fig 4: Mini Type Fuel Pump Relay Terminals
    G96D01020
    Fig 5: Fuel Pump Relay Terminals
    G96F01021
  3. Step 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. Step 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. Step 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 and DTC P0231 or P0232 is present, go to next step. If resistance is less than 5 ohms and DTC P0231 or P0232 is not present, replace PCM and repeat QUICK TEST. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST .
  6. Step 6) Check PCM Fuel Pump Circuit  Leave ignition off. Reconnect PCM and fuel pump relay. Connect scan tester to DLC. Turn ignition on. Using scan tester, access FPA PID or FPF PID. If scan tester indicates YES or ON, replace PCM and repeat QUICK TEST . If scan tester does not indicate YES or ON, go to next step.
  7. Step 7) Leave scan tester accessed to FPA PID or FPF PID. Using starter, crank engine. If scan tester indicates YES or OFF during crank, replace PCM and repeat QUICK TEST . If scan tester does not indicate YES or ON during crank, 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.
  8. Step 10) KOEO & KOER DTC P0232  If engine starts, go to next step. If engine does not start, go to step 15). For Continuous Memory DTC P0232, go to step 30).
  9. Step 11) Check Fuel Pump  Turn ignition on for 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).
  10. Step 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 .
  11. Step 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, go to next step. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST .
  12. Step 14) Check PCM Fuel Pump Circuit  Leave ignition off. Reconnect PCM and fuel pump relay. Connect scan tester to DLC. Turn ignition on. Using scan tester, access FPM PID. If scan tester indicates OFF, fuel pump primary circuit is okay and testing is complete. If scan tester does not indicate OFF, replace PCM and repeat QUICK TEST .
  13. Step 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 .
  14. Step 16) Leave ignition off and IFS switch disconnected. Disconnect fuel pump relay. Measure resistance between POWER-TO-PUMP terminal at fuel pump relay connector and POWER-TO-PUMP terminal at IFS connector. If resistance is less than 7 ohms, go to next step. If resistance is 7 ohms or more, repair open in POWER-TO-PUMP circuit and repeat QUICK TEST .
  15. Step 17) Leave ignition off, fuel pump relay and IFS switch disconnected. Measure resistance between fuel pump motor ground circuit at 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 motor ground circuit and repeat QUICK TEST .
  16. Step 18) Leave ignition off, fuel pump relay and IFS switch disconnected. Measure resistance between POWER-TO-PUMP terminal at fuel pump connector and POWER-TO-PUMP terminal at IFS connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in POWER-TO-PUMP circuit, repeat QUICK TEST .
  17. Step 19) Leave ignition off, fuel pump relay and IFS switch disconnected. Measure resistance between fuel pump motor terminals. If resistance is less than 10 ohms, fuel pump circuits are okay and testing is complete. If resistance is 10 ohms or more, replace fuel pump and repeat QUICK TEST .
  18. Step 20) KOEO & KOER DTC P0231  If engine starts, replace PCM and repeat QUICK TEST . If engine does not start, go to next step. For Continuous Memory DTC P0231, go to step 35).
  19. 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 .
  20. Step 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 10 ohms or more, repair open in POWER-TO-PUMP circuit, 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.
  21. Step 30) Continuous Memory DTC P0232  Turn ignition off. Connect scan tester to Data Link Connector. 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. fuel pump. 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.
  22. Step 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 jumper wire between test pins No. 77 (PWR GND) and 80 (FP). 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.
  23. Step 40) Continuous Memory DTC P0230  Turn ignition off. Connect scan tester to Data Link Connector. Turn ignition on and wait 5 seconds. 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.
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