Did you perform the Instrument Cluster Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

Verify that the tachometer is inaccurate.

Does the tachometer operate normally?

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Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

1. With a scan tool select Powertrain, Data Display, Engine Data Display, and Data in order to monitor the engine speed.
2. Start the engine.
3. Compare the engine speed on the scan tool to the engine speed displayed on the tachometer.

Does the scan tool agree with the tachometer?

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Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 4

1. Test the tachometer signal circuit at the instrument cluster connector by backprobing with a J 39200 digital multimeter (DMM). Refer to Instrument Cluster Replacement and also refer to Circuit Testing in Wiring Systems.
2. Select the AC Voltage scale, then select frequency
3. Measure the frequency between the tachometer signal circuit on the instrument cluster connector and a good ground with the engine idling.

Does the DMM display the frequency within the specified range?

15-25 HZ Engine Idling

Go to Step 5

Go to Step 6

Replace the instrument cluster. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

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Go to Step 8

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Test the tachometer signal circuit for following conditions:

Refer to Testing for Intermittent Conditions and Poor Connections , Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 8

Go to Step 7

Replace the VCM/PCM. Refer to Powertrain Control Module Replacement/Programming in Engine controls -2.2L or Powertrain Control Module Replacement/Programming in Engine controls -2.2L (L43) or VCM Replacement/Programming in Engine controls -4.3L.

Did you complete the replacement?

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Go to Step 8

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Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 3