Brake Light Switch: Description and Operation

BRAKE PEDAL POSITION (BPP) SWITCH

Typical Brake Pedal Position (BPP) Switch:

The 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 and for vehicle speed control deactivation. Depending on the vehicle application the BPP switch can be connected to the PCM in the following manner:
- BPP switch is hard wired to the PCM supplying battery positive voltage (B+) when the vehicle brake pedal is applied.
- BPP switch is hard wired to a module (ABS, LCM, or REM), the BPP signal is then broadcast over the data link to be received by the PCM.
- BPP switch is hard wired to the anti-lock brake system (ABS) traction control/stability assist module. The stability module will interpret the BPP switch input along with other ABS inputs and generate an output called the driver brake application (DBA) signal. The DBA signal is than sent to the PCM and to other BPP signal users.

NOTE: On applications where the BPP switch is hard wired to the PCM and stop lamp circuit, if all stop lamp 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 stop lamp bulbs has failed.