Brake Light Switch: Description and Operation

PURPOSE
The Brake ON/OFF (BOO) switch signals the Powertrain Control Module (PCM) with Battery Positive Voltage (B+) when the brakes are APPLIED.

OPERATION
The PCM will adjust the engine idle speed with the brakes APPLIED and A/C turned ON, or will turn OFF the A/C for a calibrated time.

On vehicles with locking torque converters, the signal will tell the PCM to disengage the torque converter.