GM Service Manual Online
For 1990-2009 cars only

Brake System Indicator

The body control module (BCM) sends a message to the IPC via the serial peripheral interface (SPI) requesting illumination. The IPC illuminates the brake indicator when the following occurs:

    • The BCM detects that the park brake is engaged. If the vehicle speed is greater than 5 km/h (3.1 mph) with the park brake engaged, the BCM sends a class 2 message to the radio in order to activate an audible warning.
    • The BCM detects a low brake fluid condition, signal circuit is low. The BCM also sends a class 2 message to the radio in order to activate an audible warning.
    • The BCM detects a malfunction in the brake fluid level circuit. The BCM also sends a class 2 message to the radio in order to activate an audible warning.
    • The electronic brake control module (EBCM) detects a malfunction in the braking system. The BCM receives a class 2 message from the EBCM requesting illumination. The BCM also sends a class 2 message to the radio in order to activate an audible warning.
    • The IPC performs the displays test at the start of each ignition cycle as commanded by the BCM. The indicator illuminates for approximately 3 seconds.