GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: Instrument Cluster Schematics

Connector End View Reference: Instrument Panel, Gages, and Console Connector End Views , Powertrain Control Module Connector End Views , or Powertrain Control Module Connector End Views

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. 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 parameter in the PCM Engine Data 1 data list.

Does the Vehicle Speed parameter match the speedometer display?

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Go to Step 3

Go to Step 4

3

Does the odometer operate properly?

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

Go to Step 9

4

  1. Turn the ignition OFF.
  2. Disconnect the PCM connector C2.
  3. Turn the ignition ON.
  4. Measure the voltage from the vehicle speed signal circuit to a good ground.

Does the voltage measure greater than the specified value?

9.0 V

Go to Step 7

Go to Step 5

5

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

Did you find and correct the condition?

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Go to Step 11

Go to Step 6

6

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 11

Go to Step 9

7

Test the vehicle speed signal circuit for a short to voltage between the IPC and the PCM. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 11

Go to Step 8

8

Inspect for poor connections at the harness connector of the PCM. 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 11

Go to Step 10

9

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

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Go to Step 11

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10

Important:: Program the replacement PCM.

Replace the PCM. Refer to the following procedures:

    •  Powertrain Control Module Replacement in Engine Controls - 2.2L
    •  Powertrain Control Module Replacement in Engine Controls - 4.3L

Did you complete the replacement?

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Go to Step 11

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11

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2