Electronic Throttle Actuator: Description and Operation
Description of Electric Throttle Control SystemThe Electric Throttle Control System consists of the following.
- Throttle body incorporated with the throttle valve, throttle actuator and throttle position (TP) sensors (main/sub)
- Accelerator pedal assembly incorporated with accelerator pedal position (APP) sensors (main/sub)
- ECM
Operation Description
ECM (5) detects depressed extent of the accelerator pedal based on the signal voltage of the APP sensor (1). Using that data and engine operation condition, ECM calculates the targeted throttle valve opening. On the other hand, it detects the throttle valve opening based on the signal voltage of the TP sensor (3) in the throttle body (2) and compares it with the above targeted throttle valve opening. When there is a difference between them, ECM controls the duty ratio (100% - 0%) of throttle actuator control according to this difference in order to drive the throttle actuator (4) in the throttle body. When there is no difference, ECM controls the duty ratio of throttle actuator targeted maintain the throttle valve opening. In this way, the throttle valve (8) is opened and closed to achieve the optimum throttle valve opening.
In this system, TP sensor and APP sensor have two sensors (main and sub) each to assure highly accurate and reliable control and abnormality detection. Also, when ECM detects an abnormality in the system, it turns off the throttle actuator. When the throttle actuator is turned off, the throttle valve is fixed at the opening of about 22 - 27 ° (default opening) from its completely closed position by the balance of the return spring and open spring in the throttle body. This throttle body is not equipped with IAC valve for idle speed control. Idle speed control is operated by the throttle actuator.
Description of Electric Throttle Control System Calibration
ECM calculates the throttle valve position on the basis of the completely closed throttle valve position data.
The completely closed throttle valve position (signal voltage from TP sensor) of each system differs due to the individual differences of the throttle valve, the TP sensor and the APP sensor. As such differences must be taken into account for controlling the throttle valve, it is necessary to calibrate the completely closed throttle valve position data in ECM.
After performing any one of the following service, it is necessary to calibrate the completely closed throttle valve position stored in ECM.
- Shutoff of backup power for ECM (i.e. disconnection of battery cable, replacement of battery or blown "ECM" fuse)
- Replacement of ECM
- Clearance of DTC related to electric throttle control system (DTC related to electric throttle control system: P0607, P0122, P0123, P0222, P0223, P2100, P2101, P2102, P2103, P2111, P2119, P2122, P2123, P2127, P2128, P2135 or P2138)
- Replacement of throttle body