GM Service Manual Online
For 1990-2009 cars only

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

  1. Perform Diagnostic System Check - Hydraulic Brakes before using the symptom tables in order to verifty 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. Review the system operation in order to familiarize yourself with the system functions. Refer to the following:
  4. •  Master Cylinder Description
    •  Vacuum Brake Booster Description
    •  Brake Warning System Operation
    •  Brake Warning System Circuit Description

Visual/Physical Inspection

    • Inspect for aftermarket devices which may affect the operation of the instrument panel cluster. Refer to Checking Aftermarket Accessories in Wiring Systems.
    • Inspect the easily accessible or visible system components for obvious damage or conditions which may cause the symptom.
    • Inspect the reservoir for the proper fluid level.

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
    •  Brake Fluid Leak