Brake Pedal Position (BPP) Switch
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2007 Ford RV Cutaway, 2007 Ford Pickup, 2007 Ford F550 Super Duty, 2007 Ford F450 Super Duty, and 2007 Ford Econoline. However, it is still accessible from the selected car via links, so may be relevant.
The BPP switch signals the PCM with a battery positive voltage (B+) signal whenever the brake pedal is applied.
The signal informs the PCM to disengage the torque converter clutch, speed control, and auxiliary idle control (if equipped).
If all the stoplamp bulbs are burned out (open), a 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 BPP switch has failed.