Was the instrument panel cluster (IPC) system check performed?

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Go to Step 2

Go to Instrument Cluster System Check

1. With a scan tool select Powertrain, Data Display, Engine Data Display, and Data to monitor the engine speed.
2. Start the engine.
3. Compare the engine speed on the scan tool to the engine speed displayed on the tachometer.

Does the scan tool agree with the tachometer?

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Go to Intermittents and Poor Connections Diagnosis

Go to Step 3

With the scan tool read the powertrain control module DTCs.

Does the scan tool display any DTCs?

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Powertrain On Board Diagnostic (OBD) System Check for 4.3L or

Powertrain On Board Diagnostic (OBD) System Check for 4.8L, 5.3L, and 6.0L

Go to Step 4

1. Check for a RPM input signal to the cluster by backprobing with a DMM.
2. Measure the AC voltage between the WHT (121) wire cavity A2 and ground.

Is the AC voltage within the specified range?

5.0-7.0 VAC

Go to Step 5

Go to Step 6

Replace the instrument cluster. Refer to Instrument Cluster Replacement

Is the repair complete?

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Go to Instrument Cluster System Check

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Check the following items:

1. The WHT (121) wire for an open circuit between the cluster to the VCM/PCM.
2. The WHT (121) wire for a short to ground between the cluster to the VCM/PCM.
3. The WHT (121) wire for a short to battery between the cluster to the VCM/PCM.
4. All electrical connectors for proper matting.
5. Repair any problem found.

Was a problem found and corrected?

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Go to Instrument Cluster System Check

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