GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

Start the vehicle.

Does the tachometer show the correct engine RPM?

--

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

Go to Step 3

3

Does the tachometer always indicate low RPMs?

--

Go to Step 5

Go to Step 4

4

Does the tachometer always indicate high RPMs?

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Go to Step 5

Go to Diagnostic System Check - Instrument Cluster

5

  1. Connect a scan tool to the vehicle data link connector (DLC).
  2. Using the scan tool, perform the engine tachometer gage sweep test.

Does the tachometer gage sweep from low RPMs to high RPMs and return to low RPMs when prompted?

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Go to Powertrain On Board Diagnostic (OBD) System Check (3.8L) or Powertrain On Board Diagnostic (OBD) System Check (5.7L)

Go to Step 6

6

Replace the instrument cluster. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

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Go to Step 7

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7

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 3