GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Inspect the vehicle for diagnostic trouble codes (DTCs).

Has the vehicle been inspected for diagnostic trouble codes (DTCs)?

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Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls 3.1 or Powertrain On Board Diagnostic (OBD) System Check in Engine Controls 3.8

2

Operate and inspect the speedometer.

Is the speedometer operating correctly?

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Go to Step 3

Go to Speedometer and/or Odometer Inoperative

3

  1. Disconnect the powertrain control module (PCM) connector C1.
  2. Turn the ignition switch to the RUN position.

Does the charge warning indicator light?

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Go to Step 4

Go to Step 5

4

  1. Inspect for a short to ground in CKT 25.
  2. Replace the instrument cluster if CKT 25 is good. Refer to Instrument Cluster Replacement .
  3. Inspect the system.

Is the repair complete?

--

System OK

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5

  1. Connect a fused (3 amp) jumper between the PCM harness connector C1 terminal 36 and ground.
  2. Turn the ignition switch to the RUN position.

Does the charge warning indicator light?

--

Go to Charging System Check in Engine Electrical

Go to Step 6

6

Inspect for a poor connection or an open in CKT 25.

Did you find a poor connection or open in CKT 25?

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Go to Step 7

Go to Step 8

7

  1. Repair the poor connection or open in CKT 25.
  2. Inspect the system.

Is the repair complete?

--

System OK

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8

  1. Inspect the warning indicator bulb and bulb connection.
  2. Replace the instrument cluster. Refer to Instrument Cluster Replacement .
  3. Inspect the system.

Is the repair complete?

--

System OK

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