Brake Light Switch: Description and Operation

Brake Pedal Position Switch

Typical Brake Pedal Position Switch:

The Brake Pedal Position (BPP) switch provides power to the stoplamps. The LCM signals various other systems, including:
^ Anti-lock brake control module.
^ Powertrain Control Module (PCM).
^ Shift lock actuator.
^ Speed control servo.

The Brake Pedal Position (BPP) switch is used by the PCM to disengage the transmission torque converter clutch and on some applications as an input to the idle speed control for idle quality. On most applications the BPP switch is hard wired to the PCM and supplies battery positive voltage (B+) when the vehicle brake pedal is applied. On other applications the BPP switch signal is broadcast over the SCP link via another module to be received by the PCM.

On applications where the BPP switch is hard wired to the PCM and stoplamp circuit, if all stoplamp bulbs are burned out (open), high voltage is present at the PCM due to a pull-up resistor in the PCM. This provides fail-safe operation in the event the circuit to the stoplamp bulbs has failed.