GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Blazer - 2WD 🢒 Body and Accessories 🢒 Instrument Panel, Gages, and Console 🢒 Tachometer Inaccurate or Inoperative

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. Start the engine.
  3. With the scan tool, observe the Engine Speed parameter in the PCM Engine Data 1 data list.

Does the Engine Speed parameter match the tachometer display?

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

Go to Step 3

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

Does the voltage measure greater than the specified value?

9.0 V

Go to Step 6

Go to Step 4

4

Test the engine 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?

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Go to Step 10

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 Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 10

Go to Step 8

6

Test the engine speed signal circuit for a short to voltage. 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 10

Go to Step 7

7

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 10

Go to Step 9

8

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

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Go to Step 10

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9

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 10

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10

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2