GM Service Manual Online
For 1990-2009 cars only

Important: The following steps must be completed before using the symptom tables.

  1. Perform the Diagnostic System Check - Hydraulic Brakes before using the brake indicator symptom tables in order to verify that all of the following are true:
  2. • There are no DTCs set.
    • The control module(s) can communicate via the serial data link.
  3. Perform the Brake System Diagnosis before using the hydraulic brake system symptom tables.
  4. Review the system operation in order to familiarize yourself with the system functions. Refer to the following:
  5. •  Master Cylinder Description
    •  Brake Fluid and Brake Fluid Handling
    •  Vacuum Brake Booster Description
    •  Brake Warning System Circuit Description

Visual/Physical Inspection

    • Inspect for aftermarket devices which could affect the operation of the Brake Warning 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 brake fluid 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 Pedal Excessive Travel
    •  Brake Pedal Travel Gradually Increases
    •  Brake Pedal Excessive Effort
    •  Brake Pulsation
    •  Brake System Slow Response
    •  Brake System Slow Release
    •  Brakes Drag
    •  Braking Action Uneven - Side to Side
    •  Braking Action Uneven - Front to Rear
    •  Brake System Noise with Brakes Applied
    •  Brake System Noise with Brakes Not Applied
    •  External Conditions that Affect Brake Performance
    •  Brake Pedal Travel
    •  Brake Fluid Leak
    •  Master Cylinder Diagnosis
    •  Brake Hose and Pipe Diagnosis
    •  Vacuum Booster Diagnosis