P1129 TOYOTA Possible Causes
- Faulty Electronic Throttle Control System (ETCS) actuator
- Electronic Throttle Control System (ETCS) actuator harness is open or shorted
- Electronic Throttle Control System (ETCS) actuator circuit Poor electrical connection
How to Fix Code P1129 TOYOTA?
Start by checking the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
When is the Code Detected?
The P1129 code is set when the throttle opening angle continues to vary significantly from the target throttle opening angle.
Possible Symptoms
- Check Engine Light on (or Service Engine Soon Warning Light)
P1129 TOYOTA Meaning
The Electronic Throttle Control System (ETCS) consists of the throttle motor to actuate the throttle valve, the electromagnetic clutch to connect the throttle motor to the throttle valve, the throttle position sensor to detect the throttle valve opening angle, the accelerator pedal position sensor to detect the accelerator pedal position, the Engine Control Module (ECM) to control the ETCS, and the single throttle valve body.
The ECM controls the throttle motor to make the throttle valve opening angle properly under responsive driving conditions.
The throttle position sensor, which is mounted on the throttle body, detects the throttle valve opening angle and provides feedback to the ECM to control the throttle motor.
In case of ETCS malfunction, the ECM cuts power to the throttle motor and the magnetic clutch, and the throttle valve is fully closed by the return spring.
However, the throttle valve opening angle can be controlled by the accelerator pedal via the throttle cable.