GM Service Manual Online
For 1990-2009 cars only

Important: Review the system operation in order to familiarize yourself with the system functions. Refer to the following:

   •  Master Cylinder Description
   •  Proportioning Valve Description
   •  Brake Fluid and Brake Fluid Handling
   •  Vacuum Brake Booster Description
   •  Vacuum Brake Booster Operation
   •  Brake Warning System Operation
   •  Brake Warning System Circuit Description

Visual/Physical Inspection

    • Inspect for aftermarket devices which could affect the operation of the Hydraulic Brake System. Refer to Checking Aftermarket Accessories in Wiring Systems.
    • Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
    • Inspect the master cylinder reservoir for the proper brake fluid level. Refer to Master Cylinder Reservoir Filling .

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

    •  Brake Warning Indicator Always On
    •  Brake Warning Indicator Inoperative
    •  Brake System Diagnosis
    •  Brake Pedal Excessive Travel
    •  Brake Warning Indicator, Message, and Chime Always On
    •  Brake Warning Indicator and Chime Inoperative
    •  External Conditions that Affect Brake Performance
    •  Brake Fluid Leak
    •  Hydraulic System Fluid Loss
    •  Brake Hose and Pipe Diagnosis