For 1990-2009 cars

Cause | Correction
--- | ---
DEFINITION: Inspect for proper gear oil levels prior to performing system diagnosis.
Low gear oil levels |

• | Fill axle to the recommended level.

• | A low level may create intermittent or incomplete clutch park engagement.

Incorrect gear oil |

• | Replace with gear oil, GM P/N 9986115.

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

Worn clutch pack oil pump | Replace the clutch coupling assembly.
Worn clutch pack friction discs | Replace the clutch coupling assembly.