Function
The signal of the stop lamp switch influences fuel metering when the brake is applied and a gear is engaged at idle speed.
Example: During braking, the PCM receives a signal from the stoplamp switch which results in the fuel quantity for idle control being reduced. This prevents the idle control system from continuing to maintain idle speed and counteracting the braking action.
In addition, there is a BPP switch installed. In vehicles with a speed control system, the stoplamp switch and the BPP switch both send the “brake applied” signal to the PCM for safety reasons.
In addition, the signals from both switches are used to check the APP sensor (plausibility check).
