GM Service Manual Online
For 1990-2009 cars only
  1. Run the engine at idle.
  2. Put the range selector lever in NEUTRAL.
  3. Depress the brake pedal. Hold the brake pedal with constant foot pressure.
  4. If the pedal gradually falls away with constant pressure, the brake hydraulic system may be leaking. Inspect the hydraulic system for any suspected leaks.
  5. Inspect the master cylinder fluid level.
  6. • A slight drop in the master cylinder reservoir level results from normal pad wear. The reservoir may be as low as 25.4 mm (1.0 in) from the top if the pads are worn. This condition is not abnormal.
    • An abnormally low level in the reservoir indicates a leak in the system. The brake hydraulic system may be leaking either internally or externally. Refer to Hydraulic Brake Diagnostic System Check . The system may appear to pass this test but still have a slight leakage.
  7. Inspect the brake pipe and the brake hose connections for brake fluid leaks.
  8. If any leaks are found, replace the hose or the pipe.
  9. If any hoses or pipes are replaced, inspect the connecting brake component for damage. If damage is found, rebuild or replace the component.
  10. Inspect the brake caliper boots and rear wheel cylinder boots for leaks.
  11. If any leaks are found, rebuild or replace the part in question. Refer to Disc Brakes.

Brake Hose and Pipe Inspection

Notice: Do not allow components to hang from the flexible brake hoses as damage to the hoses may occur. Some brake hoses have protective rings or covers to prevent direct contact of the hose with other chassis parts. Besides causing possible structural damage to the hose, excessive tension could cause the hose rings to move out of their proper locations.

Inspect the brake hoses at least twice a year for the following conditions:

    • Road hazard damage
    • Cracks
    • Chafing of the outer cover
    • Leaks
    • Blisters

Use a light and a mirror for an adequate inspection. Replace any hoses with any of the above conditions.