Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Electronic Throttle Control System Description
Overview
The electronic throttle control system (ETCS) opens and closes the throttle valve by electronic control. This system consists of a throttle actuator built into the throttle body, throttle valve and throttle position (TP) sensor A/B, accelerator pedal position (APP) sensor A/B, ETCS driver built into the powertrain control module (PCM).
ETCS is a system that opens and closes the throttle valve electronically, it has various functions such as:
- Idle Control Function
- Accelerator Control Function
- Fail-Safe Function
- Relationship Action with Other Systems
Control
When the accelerator pedal is operated, APP sensors are driven and the accelerator pedal position is detected. The accelerator pedal position is delivered to the PCM, and the PCM drives the throttle actuator in the throttle body based on the delivered throttle pedal position to open or close the throttle valve. Throttle position is detected by the TP sensors in the throttle body and delivered to the PCM. The PCM drives the throttle actuator to control the throttle position during idling, during various system control, and when necessary, as well as based on the signals from the APP sensors.
Change of ETCS control (with ECON)
The ECON ON mode softens throttle valve control to reduce fuel consumption when the accelerator pedal is roughly depressed. Also, throttle opening becomes slow in comparison with the ECON OFF mode. However, if the accelerator pedal is depressed more than a certain level, control automatically becomes equivalent to the ECON OFF mode in order to ensure the acceleration.
Change of ETCS control (Type-R)
In the +R mode and the SPORT mode, the PCM varies the throttle valve opening characteristics. Accelerator response is improved by correcting the amount that the accelerator pedal is actually depressed by moving it in the throttle valve open direction.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.