| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES - LEXUS article in GENERAL INFORMATION. |
Circuit Description
Note. Brake switch may also be referred to as stoplight switch.
This signal is used to detect when brakes have been applied. STP signal voltage is same as voltage supplied to stop lights. STP signal is used mainly to control fuel cutoff engine speed (fuel cutoff engine speed is reduced slightly when vehicle is braking). DTC is set when stop light switch does not turn off even when vehicle is driven (1 trip detection logic). Possible causes are
- Short in stoplight switch signal circuit.
- Faulty stoplight switch.
- Faulty ECM.