GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Instrument Cluster Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

  1. Properly support the vehicle so that the wheels are off the ground. Refer to Lifting and Jacking the Vehicle in General Information.
  2. With the scan tool select Powertrain, Engine Data, and Data in order to monitor the vehicle speed.
  3. Start the engine. Place the transmission in gear and the wheels spinning.
  4. Compare the vehicle speed on the scan tool to the speed displayed on the speedometer.

Does the scan tool agree with the speedometer?

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Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Inspect for a speed input signal to the cluster by backprobing with a J 39200 digital multimeter (DMM).
  2. Select the AC Voltage scale then select frequency.
  3. Measure between the vehicle speed signal and ground.

Does the frequency measure within the specified range?

18-25 HZ (at 20 MPH)

Go to Step 4

Go to Step 5

4

Replace the instrument cluster. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

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Go to Step 6

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5

Test the vehicle speed sensor circuit for an open, short to ground, or a short to voltage.

Did you find and correct the condition?

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Go to Step 6

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6

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 3