GM Service Manual Online
For 1990-2009 cars only

Cause

Correction

DEFINITION: A faulty internal transfer case component that causes a grating noise in the transfer case while in the AWD, 4HI, or 4LO mode.

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

Broken clutch apply plate

  1. Inspect for a broken clutch apply plate. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  2. Replace the apply plate and the transfer case components that are damaged from debris. Refer to Transfer Case Disassemble and Transfer Case Assemble .

Faulty control actuator lever thrust bearings

  1. Inspect for faulty control actuator lever thrust bearings. Refer to Two/Four Wheel Drive Shift Components Cleaning and Inspection .
  2. Recondition the transfer case components that are damaged from debris. Refer to Transfer Case Disassemble and Transfer Case Assemble .