The ETCS-i controls the throttle valve opening angle to the optimum amount in accordance with the amount which the accelerator pedal is depressed.
1. Normal-mode control, Power-mode control and Snowmode control
Basically, the normal-mode is used, but the control switch can be used to switch to the snow-mode or power-mode.
Normal-mode control
This is the basic control that maintains a balance of easy operation and smooth driving.
Snow-mode control
This control keeps the throttle valve opening smaller than when in the normal-mode to prevent slipping when driving on a slippery road, such as a snowy road.
Power-mode control
In this mode the throttle valve is open much wider than in the normal-mode. Therefore, this provides a more direct response against the accelerator pedal operation and more powerful driving than the normal- mode. This mode is only provided in some models.
2. Torque activated power train control
This control makes the throttle valve opening smaller or larger than the accelerator pedal depression angle to attain smooth acceleration. The illustration shows when the accelerator pedal kept at a certain depressed position. For models without the torque activated power train, the throttle valve is opened nearly in sync with the accelerator pedal motion, which, for a short period of time, causes the vehicle’s longitudinal G to rise rapidly and then gradually decline. Compared to this, in models with torque activated power train control, the throttle valve is opened gradually so that the vehicle’s longitudinal G continues for a long time to attain smooth acceleration.
3. Other controls
(1) Idle speed control
This controls the throttle valve on the closing side to maintain the ideal idling speed.
(2) Shift shock reduction control
This control reduces the throttle valve opening angle and lowers the engine torque simultaneously with the ECT
(Electronically Controlled Transmission) control when the automatic transmission shifts to reduce the shift shock
(3) TRAC (Traction Control) throttle control
If excessive slip is generated by the drive wheels, as part of the TRAC system, the request signal from the skid control ECU will close the throttle valve to reduce the power to promote vehicle stability and attain driving force.
(4) VSC (Vehicle Skid Control) coordination control
This controls the throttle valve opening angle using integrated control with the skid control ECU to make maximum utilization of the VSC system control effect.
(5) Cruise control
In the conventional cruise control, the cruise control ECU opens and closes the throttle valve via a cruise control actuator and cable. But with ETCS-i, the engine ECU, which contains an integrated cruise control ECU, directly controls the throttle valve opening angle via a throttle control motor to perform the cruise control operation.
4. Fail-safe
If the engine ECU detects a malfunction in the ETCS-i system, it turns ON the malfunction indicator lamp in the combination meter to notify the driver.
The accelerator pedal position sensor contains sensor circuits for two systems, main and sub. If a malfunction occurs in one of the sensor circuits, and the engine ECU detects an abnormal voltage difference in the signals between the two sensor circuits, the engine ECU switches to the limp mode. In the limp mode the remaining circuit is used to calculate the accelerator pedal opening angle and the vehicle is driven with the throttle valve opening restricted more than normally. In addition, if there seemed to be a malfunction with both circuits, the engine ECU places the throttle valve in the idling state. At this time, the vehicle can only be moved within the idling range.
The throttle position sensor also contains sensor circuits for two systems, main and sub. If a malfunction occurs in the sensor circuit(s), and the engine ECU detects an abnormal voltage between the two sensor circuits, the engine ECU cuts off the current to the throttle control motor and then switches to the limp mode. At this time, the throttle valve opening is fixed by the return spring, and the injection volume and ignition timing are controlled by the accelerator pedal signal. The engine output is greatly restricted, but the vehicle can be driven.
When the engine ECU detects a malfunction in the throttle control motor system, then the same control as for a malfunction of the throttle position sensor occurs.