Normal Operation
WARNING: This page is about a different car, the 2006 Mercury Milan, 2006 Lincoln Zephyr, and 2006 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
When the parking brake is applied, the parking brake warning indicator switch grounds circuit CCB09 (GY/BU) to the smart junction box (SJB). The SJB receives the ground signal and sends the instrument cluster a message over the communication network to illuminate the brake warning indicator. When the brake fluid level is low, the brake fluid level switch closes, and the signal from the SJB on circuit CMC19 (GY/VT) is grounded on circuit GD121 (BK/YE). When a base brake system concern is detected, the anti-lock brake system (ABS) module sends a signal to the instrument cluster over the communication network to illuminate the brake system warning indicator.