Brake Pedal Position (BPP) Switch

WARNING: This page is about a different car, the 2004 Ford Pickup, 2004 Ford F550 Super Duty, 2004 Ford F450 Super Duty, 2004 Ford Excursion, and 2004 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The brake pedal position (BPP) switch tells the powertrain control module (PCM) when the brakes are applied.
The torque converter clutch (TCC) disengages when the brakes are applied.
The BPP switch closes when the brakes are applied and opens when they are released.