Circuit Description

WARNING: This page is about a different car, the 2003 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Brake switch may also be referred to as stop light switch.

This signal is used to detect when the brakes have been applied. The STP signal voltage is the same as the voltage supplied to the stop lights. The STP signal is used mainly to control the fuel cut-off engine speed. Fuel cut-off engine speed is reduced slightly when the vehicle is braking. Possible causes are:

Short in stop light switch signal circuit.
Faulty stop light switch.
Faulty ECM.