GM Service Manual Online
For 1990-2009 cars only

Cause

Correction

DEFINITION: The transfer case is not delivering engine torque to the front propeller shaft.

Review the Symptoms - Transfer Case and perform the necessary inspections.

Viscous coupling faulty

  1. Inspect the transfer case fluid for being black. If the fluid is black, it is most likely caused by a viscous coupling failure.
  2. Test for a faulty viscous coupling. Refer to Transfer Case Description and Operation .
  3. Disassemble the transfer case. Refer to Transfer Case Disassemble in Transfer Case - NVG 149-NP3 Unit Repair.
  4. Inspect the viscous coupling for a bulged cover. Refer to Transfer Case Cleaning and Inspection in Transfer Case - NVG 149-NP3 Unit Repair.
  5. Replace the viscous coupling if it is faulty. Refer to Transfer Case Assemble in Transfer Case - NVG 149-NP3 Unit Repair.

Planetary carrier faulty

  1. Disassemble the transfer case. Refer to Transfer Case Disassemble in Transfer Case - NVG 149-NP3 Unit Repair.
  2. Inspect for faulty planetary carrier components. Refer to Transfer Case Cleaning and Inspection in Transfer Case - NVG 149-NP3 Unit Repair.
  3. Replace any faulty planetary carrier components. Refer to Transfer Case Assemble in Transfer Case - NVG 149-NP3 Unit Repair.