Note. For information on engine immobilizer system, see COMPUTERIZED ENGINE CONTROLS in THEORY & OPERATION article.
| 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. |
Circuit Description
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.