Brake Pedal Position (BPP) Switch
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2004 Ford RV Cutaway, 2004 Ford Pickup, 2004 Ford F550 Super Duty, 2004 Ford F450 Super Duty, and 2004 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.
The brake pedal position (BPP) switch signals the PCM with a battery positive voltage (B+) signal whenever the vehicle 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.