Signal Function
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2006 Ford RV Cutaway, 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Econoline. However, it is still accessible from the selected car via links, so may be relevant.
The BPA switch provides a backup signal for the brake pedal position (BPP) switch. If the BPP switch signal is lost, the BPA switch provides the brakes-applied signal to deactivate the speed control system.