Inspect for the proper transaxle and gear oil levels prior to performing system diagnosis. Refer to Transfer Case Fluid Replacement .

Loose propeller shaft mounting bolts

Tighten the bolts as required. Refer to Propeller Shaft Replacement in Propeller Shaft.

Worn propeller shaft constant velocity joints

Replace the propeller shaft assembly. Refer to Propeller Shaft Replacement in Propeller Shaft.

Worn axle shaft constant velocity joints

Replace the constant velocity joints as required.

Loose rear differential torque tube bracket or a damaged bracket bushing

Tighten the bracket bolts or replace the bracket as required.

Worn bearing in the rear axle torque tube assembly

Replace the torque tube assembly.

Incorrect gear oil in the transfer case

Replace with gear oil GM P/N 12378514 (Canadian P/N 88901045).

Bearing noise within the transfer case

A "grinding" or "roar" type noise will increase or decrease relative to the vehicle speed.

1. Check for the proper fluid level. Fill as required.
2. If the noise continues, repair or replace the internal components as required.

Gear set "whine" noise within the transfer case

"Whine" type noises will increase or decrease relative to the vehicle speed, approximately 50-60 mph.

1. Check for the proper fluid level. Fill as required.
2. If the noise continues, repair or replace the internal components as required.

Contributing factors may include:

•	Incorrect backlash between the gear sets

•	Worn or damaged gear teeth

•	Transaxle assembly noise

•	Rear differential noise