Brake Signal: Description and Operation

Brake Pedal Position (BPP) Switch
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.

Brake Pedal Position (BPP) Switch:

Brake Pressure Applied (BPA) Switch

NOTE: The BPA switch is present on vehicles equipped with speed control.

All vehicles have a single BPA switch. A BPA switch provides a backup for the BPP switch. Normally, a brakes-applied signal from the BPP switch disengages the speed control. If the BPP switch signal is lost, the BPA switch then supplies the brakes-applied signal to the speed control system. The BPA switch signal is also used in the transmission strategy and the key on engine running (KOER) self-test.

Brake Pressure Applied (BPA) Switch: