Test C2 - Inertia Switch

Fig 1: 5.0L Fuel Pump Circuit Wiring Diagram

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: fuel lines, fuel filters, throttle body, fuel pump or contaminated fuel.

1. No Fuel Pressure: Electrical Check. Install fuel pressure gauge. Cycle key from off to on several times to check if fuel pump runs. DO NOT  crank engine. Pump should operate briefly each time key is on. If pump runs as indicated, service or replace fuel pump as necessary. If pump does not run as indicated, go to next step.
2. Checking For VPWR to ECA. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Install breakout box and connect ECA to it. With KOEO, DVOM on 20-volt scale, measure voltage between test pins No. 37 and 40 at breakout box, and between test pins No. 57 and 60 at breakout box. If either reading is less than 10.5 volts, go to TEST A2 - VEHICLE BATTERY  , step 1). If both readings are 10.5 volts or more, go to step 5).
3. Does not apply to trucks.
   Fig 2: Fuel Pump Relay Terminal Identification

   
4. Does not apply to trucks.
5. Check Voltage to Power-to-Pump Circuit. With KOEO, breakout box installed and ECA connected to it. Disconnect fuel pump circuit fuse (fuse No. 20). Reconnect fuel pump relay. Set DVOM on 20 volt scale. Measure voltage between chassis ground and power-to-pump circuit at fuel pump relay while cranking engine. If reading is less than 8 volts, go to next step. If reading is 8 volts or more, check the following: open in power-to-pump circuit, open in fuel pump and open in fuel pump ground circuit.
6. Checking BATT+ Circuit to Fuel Pump Relay. Turn key on, leaving engine off. Leave breakout box installed and ECA connected, locate fuel pump relay. Set DVOM on 20-volt scale. Measure voltage between chassis ground and BATT+ circuit at fuel pump relay. If reading is less than 10.5 volts, repair open in BATT+ circuit between fuel pump relay and battery positive post. Repeat QUICK TEST. If reading is 10.5 volts or greater, go to step 11).
7. Service Code 87: Checking VPWR Circuit to Fuel Pump Relay. Code 87 indicates a fuel pump primary circuit failure. Possible causes are: inertia switch not reset or electrically open, faulty fuel pump relay, ECA or open or shorted circuit. Turn key on, leaving engine off. Leave breakout box installed and ECA connected. Locate fuel pump relay. Set DVOM on 20-volt scale. Measure voltage between chassis ground and VPWR circuit at fuel pump relay. If reading is 10.5 volts or more, go to next step. If reading is less than 10.5 volts, ensure inertia switch is on. If inertia switch will not reset, replace switch. If switch is okay, repair open in VPWR circuit between EEC power relay and fuel pump relay. Repeat QUICK TEST.
8. Checking Fuel Pump Circuit Continuity. Turn key off and wait 10 seconds. Leave breakout box installed and ECA connected. With DVOM on 200-ohm scale, measure resistance between fuel pump circuit at pump relay and test pin No. 22 at breakout box. If reading is 5 ohms or more, repair open in fuel pump circuit. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.
9. Checking For Short to Power. Disconnect ECA and fuel pump relay. With key on, breakout box installed, set DVOM on 20-volt scale. Measure voltage between test pin No. 22 and battery negative terminal. If voltage is less than one volt, go to next step. If voltage is more than one volt, repair short circuit. Reconnect ECA and attempt to start vehicle. If vehicle fails to start, replace ECA. Rerun QUICK TEST.
10. Checking For Short to Ground. Turn key off. Leave breakout box installed and disconnect ECA. Disconnect fuel pump relay. With DVOM on 200K-ohm scale, measure resistance between test pin No. 22 and test pins No. 40 and 60 at breakout box. If reading is less than 10K ohms, repair short in fuel pump circuit. Repeat QUICK TEST. If reading is 10K ohms or more, go to next step.
11. Checking Voltage at Power-to-Pump Circuit. Leave breakout box installed and ECA disconnected. Install a jumper wire between test pin No. 22 and test pins No. 40 or 60 at breakout box. Set DVOM on 20 volt scale. With KOEO, measure voltage between chassis ground and power-to-pump circuit at fuel pump relay. If reading is 10.5 volts or more, replace ECA and repeat QUICK TEST. If reading is less than 10.5 volts, replace fuel pump relay. Connect ECA and repeat QUICK TEST.
12. Service Code 95: Check Inertia Switch. A KOEO code 95 indicates that one of the following has occurred:
    • Inertia switch not reset or electrically open.
    • Open circuit in or between ECA and fuel pump.
    • Faulty ground connection at fuel pump.
    • Fuel pump secondary circuit shorted to power.
    • Fuel pump relay contacts always closed.
    • Faulty ECA.

    Turn key off and wait 10 seconds. Locate and disconnect inertia switch. Set DVOM on 200-ohm scale. Measure resistance of inertia switch. If resistance is less than 5 ohms, reconnect inertia switch and go to next step. If resistance is more than 5 ohms, replace or reset inertia switch and rerun QUICK TEST.

13. Verifying Fuel Pump is Off. With key off, listen for fuel pump noise. If fuel pump is off, go to step 15). If fuel pump is on, go to next step.
14. Fuel Pump Relay Check. Turn key off. Remove fuel pump relay. If fuel pump turns off, replace fuel pump relay. Repeat QUICK TEST. If fuel pump does not turn off, repair short to power-to-pump circuit. Repeat QUICK TEST.
15. Checking Continuity of Fuel Pump Monitor (FPM) Circuit. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Install breakout box and leave ECA disconnected. Disconnect fuel pump relay. Set DVOM on 200-ohm scale and measure resistance between test pin No. 8 at the breakout box and power-to-pump circuit at the fuel pump relay harness. See Fig 3 . If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit and rerun QUICK TEST.
    Fig 3: Fuel Pump Relay Vehicle Harness Connector

    
16. Checking Continuity Between FPM Circuit and Ground. Turn key off. Install breakout box and disconnect ECA. Disconnect fuel pump relay. Set DVOM on 200-ohm scale and measure resistance between test pin No. 8 at the breakout box and battery negative terminal. If resistance is less than 10 ohms, remove test set-up, reconnect fuel pump relay, replace ECA and rerun QUICK TEST. If resistance is more than 10 ohms, remove test set-up and check the following: open circuit in fuel pump, poor ground connection at fuel pump, or an open in power-to-pump circuit.
17. Checking Fuel Pump Primary Circuit For Short to Ground. Turn key off and wait 10 seconds. Install breakout box and disconnect ECA. Disconnect fuel pump relay and set DVOM on 200K-ohm scale. Measure resistance between test pins No. 22 and 40 at the breakout box. If resistance is greater than 10K ohms, remove test set-up. Replace ECA, and rerun QUICK TEST. If resistance is less than 10K ohms, remove test set-up. Repair short circuit and rerun QUICK TEST.
18. Service Code 96: Checking BATT+ to Fuel Pump Relay. Service code 96 indicates a fuel pump secondary circuit failure between the BATT+ supply and the FPM connection to the POWER-to-PUMP connection. Possible causes are: faulty fuel pump relay or ECA, open circuit. Turn key off and wait 10 seconds. Locate fuel pump relay. With the DVOM on 20-volt scale, measure voltage between BATT+ circuit at fuel pump relay and battery negative. If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts, repair open circuit and rerun QUICK TEST.
19. Verifying Fuel Pump Operation. With key off, set DVOM on 20-volt scale. Connect DVOM between POWER-to-PUMP circuit at fuel pump relay and battery negative post. Check voltage while turning key to RUN position (one second) and OFF position (10 seconds). Repeat cycle at least 5 times. If voltage is greater than 10.5 volts for approximately one second after key is turned to RUN position, go to next step. If voltage is not to specification, inspect relay harness connector and if okay, replace fuel pump relay.
20. Checking Continuity of Power-to-Pump Circuit. Turn key off and disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Install breakout box and leave ECA disconnected. With DVOM on 200-ohm scale, measure resistance between test pin No. 8 at breakout box and POWER-to-PUMP circuit at relay harness connector. If resistance is less than 5 ohms, remove test set up, replace ECA, and rerun QUICK TEST. If resistance is more than 5 ohms, repair open circuit between FPM connecting splice and relay. Rerun QUICK TEST.
21. Continuous Memory Code 95: Checking EEC-IV Harness. A continuous code 95 indicates that one of the following conditions has occurred intermittently: Open circuit in or between the fuel pump and FPM circuit at the ECA. Faulty ground circuit at the fuel pump. Start engine and perform WIGGLE TEST on harness assembly to fuel pump, and to pump ground circuit harness. Lightly tap inertia switch and pump to simulate road shock. Check for engine miss or stumble while performing test. With key off, check harness connectors for corrosion or damage. Isolate and repair any faults that are found, clear Code 95 and rerun QUICK TEST. If no fault is found, go to next step.
22. Checking FPM Circuit. Turn key off. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Install breakout box and leave ECA disconnected. With KOEO, connect a test light between test pin No. 8 and test pin No. 37. With test light lit, perform WIGGLE test on FPM circuit between pump and monitor. Light should go out if fault is found during WIGGLE TEST. Isolate and repair any found faults, remove test set-up and rerun QUICK TEST. If no faults are found, go to next step.
23. Check For Short to Power. With KOEO, breakout box installed and ECA disconnected. Connect a test light between test pin No. 8 and test pin No. 40. Observe test light, perform WIGGLE test on FPM circuit and POWER-to-PUMP circuit. Lightly tap the fuel pump relay to simulate road shock. Light should go on when fault is found during WIGGLE TEST, indicating a short to power. Listen for sound of fuel pump turning on. Isolate and repair any found faults, remove test set up and rerun QUICK TEST. If no faults are found, fault is intermittent and cannot be duplicated at this time.
24. Continuous Code 96: Check For Code 87. If Code 87 is also present with Code 96, go to step 26). If code 87 is not displayed, go to next step.
25. Checking EEC-IV Harness. A continuous code 96 without an accompanying code 87 indicates one of the following occurred during vehicle operation: An open in the BATT+ circuit between the BATT+ and the fuel pump relay, relay contacts opened or open in the POWER-to-PUMP circuit from the fuel pump relay to the FPM splice. With engine running attempt to cause a miss or stumble while performing WIGGLE TEST on pump harness and connectors. With engine off, inspect all connectors for damage or corrosion. If a fault is found, isolate and repair it. Clear codes and rerun QUICK TEST. If no fault is found, fault may not be duplicated at this time. Clear memory codes, code 96 testing is complete.
26. Continuous Memory Code 87: Checking EEC-IV Harness. A continuous Code 87 indicates the primary fuel pump circuit has failed during vehicle operation. Possible causes for this fault are; An open in the VPWR circuit between the EEC power relay and the fuel pump relay, open coil in fuel pump relay or open in fuel pump circuit. Faulty inertia switch. With engine running, attempt to cause a miss or stumble while performing WIGGLE TEST on VPWR circuit between EEC power relay and fuel pump relay. Wiggle fuel pump circuit harness (test pin No. 22) between ECA and the fuel pump relay. Lightly tap fuel pump relay to simulate road shock. With key off, inspect ECA 60-pin connector for damage or corrosion. If a fault is found, isolate and repair it. Rerun QUICK TEST. If no fault is found, fault may not be duplicated at this time.