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

Water or contamination within the transmission oil

Water or contamination within the transmission fluid, causing excessive torque converter clutch slip rate, may create a "grind, growl, or moan" in the rear differential or torque tube under light or steady load conditions.

Replace the transmission fluid and flush the transfer case of the contaminated fluid. Refer to Internal Components Cleaning and Inspection in Transfer Case - Steyr Unit Repair.

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 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 axle torque tube bracket or a worn bracket bushing

Tighten the bracket bolts or replace the bracket as required.

Worn bearing in the rear differential torque tube assembly

Replace the torque tube assembly

Torque tube dampner loose or missing

A "moan" or "exhaust leak" type noise at higher engine speeds, approximately 2,000-2,500 RPM, may indicate a loose or missing dampner.

Tighten the dampner retaining bolt or replace the torque tube assembly as required.

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 80-97 km/h (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