GM Service Manual Online
For 1990-2009 cars only

Run the engine at idle and position the transaxle in NEUTRAL. Depress the brake pedal and hold a constant foot pressure. If the pedal gradually falls away with the constant pressure, the hydraulic system may be leaking. Perform the following visual inspection in order to confirm any suspected leak:

    • Inspect the master cylinder fluid levels. Normal lining wear may cause slight drop in the reservoir fluid level. An abnormally low reservoir fluid level, causing illumination of the BRAKE warning lamp, may indicate a leak in the system. The hydraulic system may leak either internally or externally.
    • Inspect for leaks at the brake pipe and brake hose connections. If leakage exists, verify the torque of the fasteners and/or replace the pipe or hose.
    • Inspect the connecting brake components for damage. Rebuild or replace the connecting brake components as necessary.
    • Inspect the caliper and wheel cylinder boots for leakage. If leakage is evident, rebuild or replace the components as necessary. Refer to Front Brake Caliper Overhaul , Rear Brake Caliper Overhaul in Disc Brakes, or Wheel Cylinder Overhaul in Drum Brakes.