GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC C Sierra - 2WD 🢒 Engine 🢒 Engine Electrical 🢒 SERVICE 4WD Warning Not Operating Properly

Step

Action

Value(s)

Yes

No

1

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

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Go to Step 2

Go to Instrument Cluster System Check

2
  1. Turn the ignition switch to the ON position.
  2. With a scan tool select Instrument Panel Cluster, Special Functions, and Lamp Test.
  3. Command the Service 4WD message ON.

Does the Service 4WD message turn ON and OFF when commanded?

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Go to Transfer Case Diagnostic System Check

Go to Step 3

3

Replace the IPC. Refer to Instrument Cluster Replacement

Is the repair complete?

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Go to Instrument Cluster System Check

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