Inspect for the proper gear oil levels prior to performing system diagnosis.

Low gear oil level

Fill the axle to the recommended level.

A low oil level may create intermittent or incomplete clutch pack engagement.

Incorrect gear oil

Replace with gear oil GM P/N United States 12378514, GM P/N Canada 88901045.

Incorrect gear oil may create improper clutch pack engagement or a slippage condition.

Worn clutch pack oil pump

Replace the clutch pack assembly.

Worn clutch pack friction discs

Replace the clutch pack assembly.