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Test F: Tachometer System Inoperative

NOTE: Do NOT start this test unless directed by a symptom diagnosis in TACHOMETER, OIL PRESSURE & COOLANT TEMPERATURE GAUGES/WARNING LAMPS  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. Remove the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect the 12-pin instrument cluster connector. 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 fuse and 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 instrument cluster and the interior fuse panel.
  5. Turn key to OFF position. 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. 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 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. 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. Is the resistance less than 5 ohms? If yes, replace the center Black diode strip. If no, service the Black/Red wire.
  8. Turn key to OFF position. Remove the instrument cluster. Disconnect the 16-pin instrument cluster connector. Connect Rotunda Inductive Dwell-Tach-Volts Ohms Tester (059-00010), or equivalent, to measure engine speed. Turn key ON, engine running. Measure the voltage on the Green/White wire at the 16-pin instrument cluster connector at the listed engine speeds. See TESTING TACHOMETER SIGNAL FROM PCM 
    TESTING TACHOMETER SIGNAL FROM PCM

    Engine Speed (RPM) Voltage
    1000 1.69
    1500 2.64
    2000 3.44
    2500 4.50
    3000 5.22

    Are the voltages OK? If yes, replace the instrument cluster. See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. If no, diagnose Powertrain Control Module (PCM) problem.

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