| WARNING | Read service precautions before proceeding with service procedure. See SERVICE PRECAUTIONS . |
Circuit Description
Electronic Throttle Control System (ETCS) uses throttle control motor to operate throttle valve. Throttle valve opening is detected by Throttle Position (TP) sensor which delivers input signals to Engine Control Module (ECM). ECM uses input signals and controls throttle control motor to provide proper throttle valve opening in response to driving conditions. DTC is set if throttle opening angle continues to vary greatly from the target throttle opening angle. If DTC P1129 exists, ECM will turn off the power to throttle control motor and throttle valve is closed by the return spring. Possible causes are
- Defective ETCS components on throttle body.
- Defective ECM.
Diagnostic Aids
Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.