Brake Lamp Switch: Operation
WARNING: This page is about a different car, the 2006 Chrysler PT Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
When the brake pedal is pressed, the plunger on the outside of the brake lamp switch extends outward. This action opens or closes the contacts of the three switches inside the brake lamp switch.
With the brake pedal pressed down (plunger extended), the switch for terminals 1 and 2 is closed completing the circuit. The switch for terminals 3 and 4 is open and so is the switch for 5 and 6.
When the brake pedal is released (plunger pushed in), the three switches assume the opposite positions. The switch for terminals 1 and 2 is now open while the other two switches are now closed, completing their circuits.