GM Service Manual Online
For 1990-2009 cars only

Use the following procedure in order to test for brake problems that may be caused by fluid leaks:

  1. Start the engine and run the engine at idle speed.
  2. Shift the transmission into neutral.
  3. Maintain constant foot pressure on the brake pedal. If the pedal slowly sinks to the floor, the hydraulic system may have internal leakage, external leakage or improperly adjusted components.
  4. Check the fluid level of the master cylinder.
  5. • A slightly low fluid level in either reservoir can result from normal wear of the front brake lining.
    • An abnormally low fluid level indicates a leak in the hydraulic system.
  6. Perform a visual inspection of the hydraulic system.
  7. If you find a leaking component, refer to the applicable replacement or overhaul procedure.

If you find no external leaks, internal leakage may be the cause. The master cylinder must be disassembled in order to diagnose internal leakage. Refer to Master Cylinder Overhaul .

Brake Hose And Pipe Inspection

Inspect the brake hoses and the brake pipes at least two times a year for the following conditions:

    • Chafing of the outer cover
    • Cracks
    • Road damage
    • Check that all hose and pipe mounting hardware is securely in place.

Replace any leaky or damaged hose or pipe. Repair any insecure mounting hardware.