GM Service Manual Online
For 1990-2009 cars only
  1. Inspect for a cracked master cylinder casting or brake fluid around the master cylinder. Leaks are indicated only if there is at least a drop of fluid. A damp condition is not abnormal.
  2. Inspect for a binding pedal linkage.
  3. Disassemble the master cylinder.
  4. 3.1. Inspect for swollen or stretched piston seal(s).
    3.2. If swollen seals are found, substandard or contaminated brake fluid should be suspected.
    3.3. Disassemble and clean all contaminated components.
  5. Replace all of the rubber components. Flush all of the brake hoses and the pipes.