GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Transfer Case Control Schematics

Connector End View Reference: Transfer Case Control Connector End Views

DEFINITION: The 4WD indicator does not illuminate with 4WD engaged. All other engine and transmission functions are normal. Refer to: Electric Motor Actuator Check in Driveline/Axle-Front Axle (w/diff).

1

Did you review the Transfer Case Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Transfer Case

2

With the engine on, place the transfer case into 4WD.

Does the 4WD indicator illuminate?

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

Go to Step 3

3

Test the 4WD indicator control circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 4

4

Inspect for a poor connection at the harness connector of the Powertrain Control Module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 5

5

Replace the PCM. Refer to the following in Engine Controls:

Did you complete the replacement?

Go to Step 6

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6

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3