Brake Light Switch: Description and Operation

Fig.2 Brake Lamp Switch:

The brake lamp switch is located under the instrument panel, at the brake pedal arm. It has three internal switches controlling various functions of the vehicle. It's main function is to control operation of the vehicle's brake lamps. Other functions include speed control deactivation, brake sense for the antilock brake system and brake sense for the brake transmission shift interlock.

CAUTION: The switch can only be adjusted once. That is during initial installation of the switch. If the switch is not adjusted properly or has been removed for some service, a new switch must be installed and adjusted.

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 is 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.