GM Service Manual Online
For 1990-2009 cars only

Low brake fluid in the brake master cylinder is caused by:

    • Normal brake lining wear
    • Hydraulic leak

Important: DO NOT fill the brake master cylinder reservoir, unless there is a hydraulic repair. Failure to follow these instructions will result in premature brake lining wear and misdiagnosis.

Notice: Do not use fluid that has a petroleum base. Do not use a container that has been used for petroleum based fluids or is wet with water. Petroleum-based fluids cause swelling and distortion of rubber parts in the hydraulic brake system and water lowers the brake fluid's boiling point. Keep all fluid containers capped to prevent contamination.


    Object Number: 1340  Size: SH
  1. Thoroughly clean the master cylinder reservoir cover before removal. This prevents dirt from entering the reservoirs.
  2. Remove the brake master cylinder cover and diaphragm.

  3. Object Number: 161485  Size: SH
  4. Add brake fluid in order to fill the reservoirs to the full mark. The full mark is located inside the brake master cylinder reservoir. Use Delco Supreme 11® Hydraulic Brake Fluid GM P/N 12377967 or an equivalent DOT 3 motor vehicle brake fluid.