Brake Indicator

The brake indicator indicates when the parking brake is applied, when certain brake hydraulic system malfunctions exists, or when the brake fluid level switch is disconnected. The brake indicator also indicates when certain faults are detected within the Antilock Brake System (ABS). The indicator is controlled by an internal transistor on the Instrument Panel Cluster (IPC) circuit board based upon the IPC programming and ABS Module or Body Control Module (BCM) CAN Bus messages.

The brake indicator Light Emitting Diode (LED) will always be OFF when the ignition switch is in any position except ON or START. The LED only illuminates when a path to ground is provided by the internal IPC transistor. When the ignition switch is turned to the ON position, the brake indicator is illuminated in the IPC for approximately three seconds. The IPC will turn ON the brake indicator for the following reasons:

• Brake Indicator Lamp-On Message  - When the IPC receives an electronic brake indicator lamp-ON  message from the ABS module, the IPC will illuminate the brake indicator. The ABS module may also send lamp-ON messages as feedback during ABS diagnostic procedures. The indicator will remain illuminated until the IPC receives a lamp-OFF message from the ABS module, or until the ignition switch is turned to the OFF position.
• Park Brake Switch Input  - When the BCM detects the gear position transitions from the park position and the park brake is applied, a CAN Bus message is sent and the IPC will flash the brake indicator ON and OFF. The indicator will continue to flash until the IPC receives a message from the BCM, or until the ignition switch is turned to the OFF position. If the park brake is not fully released, and the vehicle speed is above 8 mph (12.9 kph), an audible chime will sound.
• Antilock Brake System (ABS) Indicator Backup  - If the IPC detects a fault within the ABS indicator circuit, the IPC sends a CAN Bus message to the ABS module and then flashes the brake indicator ON and OFF. The IPC will continue to flash the brake indicator until the ABS indicator circuit fault is resolved, or until the ignition switch is turned to the OFF position.

The BCM monitors the brake fluid level switch and the park brake switch. The BCM sends the appropriate electronic messages to the ABS module and to the IPC. The ABS module continually monitors the ABS system circuits and sensors to determine if the system is operating properly. The ABS module then sends the proper lamp-ON or lamp-OFF message to the IPC. If the ABS module sends a lamp-ON message after the bulb test, this indicates that the ABS module has detected a brake hydraulic system malfunction or that the ABS system has become inoperative. The ABS module will store a DTC for any malfunction that it detects.