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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 Always On >> 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 4WD system.
  3. 4:  Determines if the failure is the result of a faulty instrument cluster.
  4. 5:  Determines if the failure is the result of a faulty PCM.
4WD Indicator Always On

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 Does the front axle disengage when the 4WD control lever is in the 2WD position? - Go to Step 4  Go to Four-Wheel Drive Does Not Disengage 
4
  1. Turn ON the ignition, with the engine OFF.
  2. Install a scan tool.
  3. Use the scan tool to command the 4WD indicator OFF.
Does the 4WD indicator turn OFF?
- Go to Step 5  Go to Step 8 
5 Test the axle switch signal circuit for voltage at the PCM.
Does the voltage measure within the specified value?
9-14 V Go to Step 6  Go to Step 7 
6 Inspect the axle switch signal circuit for a short to voltage. 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 9  -
7 Replace the PCM. Refer to Control Module References for replacement, set-up, and programming.
Did you complete the replacement?
- Go to Step 9  -
8 Replace the instrument panel cluster. Refer to Instrument Panel Cluster (IPC) Replacement .
Did you complete the replacement?
- Go to Step 9  -
9 Operate the vehicle in order to determine if the symptom has been corrected.
Is the symptom still present?
- System OK Go to Step 2