GM Service Manual Online
For 1990-2009 cars only

Speedometer and/or Odometer Inaccurate or Inoperative 8.1L Gasoline Engine

Step

Action

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the Instrument Cluster Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

  1. Install a scan tool.
  2. Raise the vehicle drive wheels. Refer to Lifting and Jacking the Vehicle in General Information.
  3. Start the engine.
  4. Place the transmission into drive for an automatic transmission or third gear for a manual transmission.
  5. With the scan tool, observe the Vehicle Speed Sensor parameter in the PCM Engine Data 1 data list.

Does the Vehicle Speed Sensor parameter match the speedometer display?

Go to Step 3

Go to Step 4

3

Does the odometer operate properly?

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

Go to Step 6

4

Test the vehicle speed signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 5

5

Inspect for poor connections at the harness connector of the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 6

6

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

Go to Step 7

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7

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2