When the park brake is applied, the park brake switch closes and supplies ground to the park brake switch signal circuit at the body control module (BCM). The BCM then sends a class 2 message to the instrument cluster (IPC) indicating that the park brake switch is applied. With the ignition ON, the IPC illuminates the BRAKE indicator. When the powertrain control module (PCM) sends a class 2 message to the BCM indicating that the vehicle is in gear for more than 8 seconds or the vehicle is moving faster than 5 km/h (3 mph), the BCM will activate the audible warning.

When the brake fluid level is low, the brake fluid level switch closes and supplies ground to the brake fluid level switch signal circuit at the electronic brake control module (EBCM). The EBCM then sends a class 2 message to the IPC and the BCM indicating that the brake fluid level is low. With the ignition ON, the IPC illuminates the BRAKE indicator and the BCM activates the audible warning.