Brake Signal: Description and Operation

The brake light switch is used as an engine controller input to signal deceleration and full stop conditions. The engine controller uses brake switch input to maintain idle at a scheduled rpm. It does this by sending signals to the Automatic Idle Speed (AIS) Motor, positioning it according to the scheduled rpm. This sensor is located on the brake pedal support bracket.

If the vehicle is equipped with an automatic transmission that has a lock-up torque converter; once the engine controller receives a signal that the brakes are being applied, it disengages the lock-up converter.