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Test H: Fuel Computer System Inoperative

NOTE: Do NOT start this test unless directed by a symptom diagnosis in FUEL COMPUTER  under TROUBLE SHOOTING.
  1. Check the 10A Meter fuse located in the interior fuse panel. Is the fuse OK? If yes, go to step  4 . If no, go to next step.
  2. Turn key to OFF position. Replace the 10A Meter fuse. Turn key to ON position. Inspect the fuse. Does the fuse fail again? If yes, go to next step. If no, go to step  4 .
  3. Turn key to OFF position. Remove the 10A Meter fuse. Disconnect the fuel computer control panel connector located on the instrument panel. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect all the instrument cluster connectors. Measure the resistance of the Gray/Blue wire between the right terminal of the 10A Meter fuse and ground. Is the resistance less than 5 ohms? If yes, service the Gray/Blue wire between the interior fuse panel and the instrument cluster. If no, replace the 10A Meter fuse and then go to next step.
  4. Turn key to OFF position. Remove the instrument cluster. Disconnect the 12-pin instrument cluster connector. Turn key to ON position. Measure the voltage on the Gray/Blue wire at the 12-pin instrument cluster connector. See CONNECTOR IDENTIFICATION  . Is the voltage greater than 10 volts? If yes, go to next step. If no, service the Gray/Blue wire between the interior fuse panel and the instrument cluster.
  5. Turn key to OFF position. Remove the instrument cluster. Disconnect the 12-pin instrument cluster connector. Measure the resistance of the Black wire between the 12-pin instrument cluster connector and ground. Is the resistance less than 5 ohms? If yes, go to step  8 . If no, go to next step.
  6. Turn key to OFF position. Remove the instrument cluster. Disconnect the 12-pin instrument cluster connector. Disconnect the center Black diode strip from the diode junction box connector located behind the instrument cluster. Measure the resistance of the Black wire between the 12-pin instrument cluster connector and terminal No. 14 of the diode junction box connector. See CONNECTOR IDENTIFICATION  . See Figure . Is the resistance less than 5 ohms? If yes, go to next step. If no, service Black wire.
  7. Turn key to OFF position. Remove the instrument cluster. Disconnect the center Black diode strip from the diode junction box connector. Measure the resistance of the Black/Red wire between terminal No. 15 of the diode junction box connector and ground. See Figure . Is the resistance less than 5 ohms? If yes, replace the center Black diode strip. See DIODE STRIPS  under REMOVAL & INSTALLATION. If no, service (Black/Red-Black) wire.
  8. Turn key to OFF position. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the negative terminal of the battery. Disconnect the 16-pin instrument cluster connector. Turn and hold the key in the START position. Measure the resistance of the Light Green/Black wire between the 16-pin instrument cluster connector and ground. See CONNECTOR IDENTIFICATION  . Is the resistance less than 5 ohms with the key in the START position? If yes, replace instrument cluster. If no, go to next step.
  9. Turn key to OFF position. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the 16-pin instrument cluster connector. Disconnect the ignition switch connector located under the steering column. Measure the resistance of the Light Green/Black wire between the 16-pin instrument cluster connector and terminal P1 of the ignition switch connector. See CONNECTOR IDENTIFICATION  .Measure the resistance of the Light Green/Black wire between the 16-pin instrument cluster connector and ground. Is the resistance less than 5 ohms between the instrument cluster connector and the ignition switch connector, and greater than 10,000 ohms between the instrument cluster and ground? If yes, diagnose problem with ignition switch. See STEERING COLUMN SWITCHES article. If no, service Light Green/Black wire.
  10. Check the 10A Electron Bat fuse located in the interior fuse panel. Is the fuse OK? If yes, go to step  13 . If no, go to next step.
  11. Turn key to OFF position. Replace the 10A Electron Bat fuse. Inspect the fuse. Does the fuse fail again? If yes, go to next step. If no, go to step  13 .
  12. Turn key to OFF position. Remove the 10A Electron Bat fuse. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the 16-pin instrument cluster connector. Measure the resistance of the Purple wire between the left terminal of the 10A Electron Bat fuse and ground. Is the resistance less than 5 ohms? If yes, service the Purple wire between the interior fuse panel and the instrument cluster. If no, replace fuse and go to next step.
  13. Turn key to OFF position. Remove the instrument cluster. Disconnect the 16-pin instrument cluster connector. Measure the voltage on the Purple wire at the 16-pin instrument cluster connector. Is the voltage greater than 10 volts? If yes, replace instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. If no, service the Purple wire between the interior fuse panel and the instrument cluster.
  14. Turn key to OFF position. Disconnect the fuel computer control panel connector located on the instrument panel. Turn key to ON position. Measure the voltage on the Gray/Blue wire at the fuel computer control panel connector. See CONNECTOR IDENTIFICATION  . Is the voltage greater than 10 volts? If yes, go to next step. If no, service the Gray/Blue wire between the interior fuse panel and the fuel computer control panel.
  15. Turn key to OFF position. Disconnect the fuel computer control panel connector. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the 16-pin instrument cluster connector. Measure the resistance of the Red/Blue wire between the fuel computer control panel connector and the 16-pin instrument cluster connector. Measure the resistance of the Red/Blue wire between the fuel computer control panel connector and ground. See CONNECTOR IDENTIFICATION  .Is the resistance less than 5 ohms between the fuel computer control panel connector and the instrument cluster connector, and greater than 10,000 ohms between the fuel computer control panel connector and ground? If yes, go to next step. If no, service Red/Blue wire.
  16. Turn key to OFF position. Reconnect the fuel computer control panel connector. Remove the instrument cluster. Disconnect the 16-pin instrument cluster connector. Turn key to ON position. Depress the OD/TRIP switch on the fuel computer control panel. Measure the voltage on the Red/Blue wire at the 16-pin instrument cluster connector. Is the voltage greater than 10 volts with OD/TRIP switch depressed? If yes, go to next step. If no, replace the fuel computer control panel. See FUEL COMPUTER CONTROL PANEL  under REMOVAL & INSTALLATION.
  17. Turn key to OFF position. Disconnect the fuel computer control panel connector. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the 16-pin instrument cluster connector. Measure the resistance of the Green wire between the fuel computer control panel connector and the 16-pin instrument cluster connector. See CONNECTOR IDENTIFICATION  . Measure the resistance of the Green wire between the fuel computer control panel connector and ground. Is the resistance less than 5 ohms between the fuel computer control panel connector and the instrument cluster connector, and greater than 10,000 ohms between the fuel computer control panel connector and ground? If yes, go to next step. If no, service Green wire.
  18. Turn key to OFF position. Reconnect the fuel computer control panel connector. Remove the instrument cluster. Disconnect the 16-pin instrument cluster connector. Turn key to ON position. Depress the TRIP/RST switch on the fuel computer control panel. Measure the voltage on the Green wire at the 16-pin instrument cluster connector. Is the voltage greater than 10 volts with the TRIP/RST switch depressed? If yes, go to next step. If no, replace fuel computer control panel. See FUEL COMPUTER CONTROL PANEL  under REMOVAL & INSTALLATION.
  19. Turn key to OFF position. Disconnect the fuel computer control panel connector. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the 16-pin instrument cluster connector. Measure the resistance of the Yellow/Green wire between the fuel computer control panel connector and the 16-pin instrument cluster connector. See CONNECTOR IDENTIFICATION  . Measure the resistance of the Yellow/Green wire between the fuel computer control panel connector and ground. Is the resistance less than 5 ohms between the fuel computer control panel connector and the instrument cluster connector, and greater than 10,000 ohms between the fuel computer control panel connector and ground? If yes, go to next step. If no, service Yellow/Green wire.
  20. Turn key to OFF position. Reconnect the fuel computer control panel connector. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the 16-pin instrument cluster connector. Turn key to ON position. Depress the ENG/MET switch on the fuel computer control panel. Measure the voltage on the Yellow/Green wire at the 16-pin instrument cluster connector. Is the voltage greater than 10 volts with the ENG/MET switch depressed? If yes, go to next step. If no, replace the fuel computer control panel. See FUEL COMPUTER CONTROL PANEL  under REMOVAL & INSTALLATION.
  21. Turn key to OFF position. Disconnect the fuel computer control panel connector. Remove the instrument cluster. Disconnect the 16-pin instrument cluster connector. Measure the resistance of the Brown wire between the fuel computer control panel connector and the 16-pin instrument cluster connector. See CONNECTOR IDENTIFICATION  . Measure the resistance of the Brown wire between the fuel computer control panel connector and ground. Is the resistance less than 5 ohms between the fuel computer control panel connector and the instrument cluster connector, and greater than 10,000 ohms between the fuel computer control panel connector and ground? If yes, go to next step. If no, service Brown wire.
  22. Turn key to OFF position. Reconnect the fuel computer control panel connector. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the 16-pin instrument cluster connector. Turn key to ON position. Depress the SELECT switch on the fuel computer control panel. Measure the voltage on the Brown wire at the 16-pin instrument cluster connector. See CONNECTOR IDENTIFICATION  . Is the voltage greater than 10 volts with the SELECT switch depressed? If yes, replace instrument cluster. If no, replace fuel computer control panel. See FUEL COMPUTER CONTROL PANEL  under REMOVAL & INSTALLATION.
  23. Turn key to OFF position. Disconnect the fuel computer control panel connector. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the 16-pin instrument cluster connector. Measure the resistance of the Green/Red wire between the fuel computer control panel connector and the 16-pin instrument cluster connector. See CONNECTOR IDENTIFICATION  . Measure the resistance of the Green/Red wire between the fuel computer control panel connector and ground. Is the resistance less than 5 ohms between the fuel computer control panel connector and the instrument cluster connector, and greater than 10,000 ohms between the fuel computer control panel connector and ground? If yes, go to next step. If no, service Green/Red wire.
  24. Turn key to OFF position. Reconnect the fuel computer control panel connector. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the 16-pin instrument cluster connector. Turn key to ON position. Depress the RESET switch on the fuel computer control panel. Measure the voltage on the Green/Red wire at the 16-pin instrument cluster connector. See CONNECTOR IDENTIFICATION  .Is the voltage greater than 10 volts with the RESET switch depressed? If yes, test the fuel flow signal. See TEST L: FUEL FLOW SENSOR (FSS) PINPOINT TEST  . If okay, then replace the instrument cluster. If no, replace fuel computer control panel. See FUEL COMPUTER CONTROL PANEL  under REMOVAL & INSTALLATION.
  25. Turn key to OFF position. Disconnect the outside air temperature sensor connector on the lower center radiator support. Connect Rotunda Instrument Gauge System Tester (021-00055) or equivalent between the Yellow wire at the outside air temperature sensor connector and ground. Turn key to ON position. Adjust the instrument gauge system tester to the shown resistances. See TESTING OUTSIDE AIR TEMPERATURE SENSOR  .
    TESTING OUTSIDE AIR TEMPERATURE SENSOR

    Resistance (Ohms) Temperature C° (F°)
    20,000 36 (97)
    40,000 20 (68)
    60,000 12 (53)
    80,000 6 (43)
    100,000 2 (35)

    Is the outside temperature display working properly? If yes, go to step  27 . If no, go to next step.

  26. Turn key to OFF position. Remove the instrument cluster. Disconnect the 12-pin instrument cluster connector. Disconnect the outside air temperature sensor connector. Measure the resistance of the Yellow wire between the 12-pin instrument cluster connector and the outside air temperature sensor connector. Measure the resistance of the Yellow wire between the 12-pin instrument cluster connector and ground. See CONNECTOR IDENTIFICATION  . Is the resistance less than 5 ohms between the instrument cluster connector and the outside air temperature sensor connector, and greater than 10,000 ohms between the instrument cluster connector and ground? If yes, replace the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. If no, service the Yellow wire.
  27. Turn key to OFF position. Disconnect the outside air temperature sensor connector. Measure the resistance of the Black wire between the outside air temperature sensor connector and ground. Is the resistance less than 5 ohms? If yes, replace the outside air temperature sensor. See OUTSIDE AIR TEMPERATURE SENSOR  under REMOVAL & INSTALLATION. If no, service Black wire.
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