Stop Lamp Switch

STOP LAMP SWITCH
The stop lamp switch is located under the dashboard touching the brake pedal. The stop lamp switch is used to turn On the stop lamps and to serve as an input to the PCM and cruise control module (if equipped). The stop lamp switch has two internal independent switches; one is used for the stop lamps and the other for the PCM/cruise control module inputs. The switch for the PCM /cruise control module is normally closed (brake pedal released, plunger depressed) and the switch for the stop lamps is normally open (brake pedal released, plunger depressed). Ignition voltage is supplied to the PCM and the cruise control module through the stop lamp switch whenever the ignition is turned On and the brake pedal is released. When the brake pedal is depressed, the PCM/cruise control module inputs go low. The stop lamp switch is also used by the PCM as an input for transaxle downshifting and TCC operation.
For example, if the transaxle is in 2nd gear and the engine speed is low with the brake pedal depressed, the PCM will unlock the torque converter. The stop lamp switch can also aid in determining if a downshift should occur while going down a hill.