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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 13 (Transfer Case - NVG 261-NP2 - Service & Troubleshooting) >> Diagnostic Information and Procedures >> 4WD Indicator Inoperative >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  Tests for an intermittent condition.
  2. 3:  Determines whether the failure is the result of a faulty front axle circuit or the instrument cluster.
  3. 4:  Tests for proper signal voltage to the PCM.
  4. 5:  Tests for proper ignition 1 voltage to the instrument cluster.
4WD Indicator Inoperative

Step Action Value(s) Yes No
Schematic Reference: Transfer Case Control Schematics 
1 Did you perform a Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 Verify the fault is present. Does the system operate normally? - Go to Testing for Intermittent Conditions and Poor Connections Go to Step 3 
3
  1. Turn ON the ignition, with the engine OFF.
  2. Install a scan tool.
  3. Use the scan tool to command the 4WD indicator ON.
Does the 4WD indicator turn ON?
- Go to Step 4  Go to Step 5 
4
  1. Ensure the 4WD control lever is in the 4WD position.
  2. Test the axle switch signal circuit for proper voltage at the PCM.
Does the voltage measure within the specified value?
9-14 V Go to Step 8  Go to Step 9 
5 Test the ignition 1 voltage circuit for a proper voltage at the instrument cluster.
Does the voltage measure within the specified value?
9-14 V Go to Step 6  Go to Step 7 
6 Replace the instrument panel cluster. Refer to Instrument Panel Cluster (IPC) Replacement .
Did you complete the replacement?
- Go to Step 10  -
7 Repair an open or high resistance in the ignition 1 voltage circuit. Refer to Circuit Testing and Wiring Repairs .
Did you complete the repair?
- Go to Step 10  -
8 Replace the PCM. Refer to Control Module References for replacement, set-up, and programming.
Did you complete the replacement?
- Go to Step 10  -
9 Inspect the axle switch signal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs . If OK, replace the front axle actuator. Refer to Electric Motor Actuator Replacement .
Did you complete the replacement?
- Go to Step 10  -
10 Operate the vehicle in order to determine if the symptom has been corrected.
Is the symptom still present?
- System OK Go to Step 2