There is an important part in Mercury Cougar known as the Brake Light Switch and this is what activates the brake lights whenever the brake pedal is pressed to relay to other drivers on the road that the car is slowing down or coming to a complete halt. This mechanism is instrumental in protection of roads stating that it acts as notice to those behind the vehicle of the movements being made. Although there can be differences in the Brake Light Switch types or styles stamped throughout the years of the Cougar production, the intention for its application stays the same in any model.