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Tachometer Control Circuit Diagnosis (Hombre 2.2L)

  1. Start engine. Vary engine speed. Observe tachometer. Turn ignition off. If tachometer indicated varying engine speed, go to step  11 . If tachometer did not vary, go to next step.
  2. Disconnect connector PCM. Using ohmmeter, measure resistance between PCM terminal No. 10 and ground. Resistance should be 1.2 ohms. If resistance is less than specified, go to next step. If resistance is higher than specified, go to step  6 .
  3. Disconnect instrument cluster. Using an ohmmeter, measure resistance between instrument cluster pins No. 8 and No. 11. Resistance should be 1.2 ohms. If resistance is less than specified, go to step  5 . If resistance is greater than specified, go to next step.
  4. Locate and repair short to ground on White wire between PCM and instrument cluster. Reconnect PCM connector. Reconnect instrument cluster. Recheck tachometer operation.
  5. Replace instrument cluster. Reconnect PCM connector. Start engine and recheck tachometer operation.
  6. Disconnect instrument cluster. Connect a self-powered test light between instrument cluster connector terminal No. 8 and PCM connector terminal No. 10 (White wire). If test light illuminates, go to step  8 . If light does not illuminate, go to next step.
  7. Locate and repair open circuit in White wire between PCM and instrument cluster. Reconnect instrument cluster and PCM. Start engine and recheck tachometer operation.
  8. Reconnect PCM connector and instrument cluster. Using a voltmeter, backprobe terminal No. 8 (White wire) of instrument cluster and ground. Start engine. Observe voltage indication. Turn ignition off. If signal voltage was present, go to next step. If signal voltage was not present, Go to step  10 .
  9. Replace instrument cluster. Start engine and recheck tachometer operation.
  10. Replace PCM. Start engine and recheck tachometer operation.
  11. Connect scan tool to DLC. Start engine. Monitor engine speed with scan tool and instrument cluster. Instrument tachometer reading should be within 100 RPM of actual engine speed. If not as specified, go to next step.
  12. Using scan tool, monitor engine RPM. Connect a DVOM with counting capability by backprobing at in-line connector between PCM and instrument cluster White wire and ground. Measure engine speed output from PCM on White wire. Monitor engine speed by scan tool. If PCM produces an accurate engine speed output (within 100 RPM of scan tool), go to step  14 . If PCM engine speed is not within specifications, go to next step.
  13. Replace PCM. Start engine and recheck tachometer operation.
  14. Replace instrument cluster. Start engine and recheck tachometer.
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