| 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
Battery positive voltage is supplied to terminal +BM of ECM even when ignition switch is off for electric throttle control system. If malfunction is detected, ECM shuts down power for throttle motor, and throttle valve is fully closed by return spring. Throttle valve is locked at a certain opening angle. Also, entire electronically controlled throttle operation is cancelled until system returns to normal and ignition switch is turned off.
DTC is set when there is an open in ETCS power source circuit and/or a faulty ECM.
Diagnostic Aids
Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records engine conditions when a malfunction is detected. When troubleshooting, it is useful to determine whether vehicle was running or stopped, engine was warmed up or not, air-fuel ratio was lean or rich, etc. at time of malfunction.