Engine ECU
The engine ECU basically controls the engine, but in the vehicle with the ETCS-i, since the throttle valve-opening angle can be controlled electrically, this type of vehicle can also have the function like cruise control ECU.
The engine ECU actuates the CCS in the same way that the cruise control ECU does.
Throttle control motor
For the vehicle with the ETCS-i, the throttle control motor regulates the throttle valve-opening angle according to the signal from the engine ECU.
The throttle control motor actuates the CCS in the same way that the cruise control actuator does.
Cruise Control ECU Operation
1.Set function
When the set function is turned on by the driver’s pushing down the lever in the SET/COAST direction and releasing it while the vehicle is driving within the cruising speed control range (between approx.40 km/h [25 mph] and 200 km/h [124 mph]) with the main switch turned on, the cruise control ECU stores the vehicle speed in the memory and keeps the vehicle at that speed.
2.Constant speed control function
The cruise control ECU compares the actual vehicle speed with the set speed. If the vehicle drives at a speed higher than the set speed, the cruise control ECU activates the actuator, making the throttle opening angle appropriate by closing the throttle. If the vehicle drives at a speed lower than the set speed, the cruise control ECU activates the actuator, making the throttle opening angle appropriate by opening the throttle.
3.Coast function
When the coast function is turned on by the driver’s pushing down the lever in the SET/COAST direction and holding it for a period of time while the vehicle is driving in the cruise control mode, the actuator closes the throttle to decelerate the vehicle speed.
The cruise control ECU stores the vehicle speed in the memory when the lever is released. After that, the cruise control ECU keeps the vehicle at that speed.
4.Accelerate function
When the accel function is turned on by the driver’s pushing up the lever in the RES/ACC direction and holding it for a period of time while the vehicle drives in the cruise control mode, the actuator opens the throttle to accelerate the vehicle speed.
The cruise control ECU stores the vehicle speed when the lever is released.
After that, the cruise control ECU keeps the vehicle at that speed.
5.Resume function
After the cruise control mode is manually cancelled by any of the cancel switches, the set speed can be resumed by the driver’s pushing up the lever in the RES/ACC direction, provided that the vehicle speed has not decreased below the lower speed limit (approx. 40 km/h [25 mph]).
The set speed cannot be resumed if the vehicle speed decreases below the lower speed limit, because the stored speed in the memory is erased.
6.Lower speed limit control function
The lower speed limit is the lowest speed at which the cruise control can be set. It is approx. 40 km/h [25 mph].
The cruise control cannot be set below this speed. If the vehicle speed decreases below this speed while the vehicle drives in the cruise control mode, the cruise control is cancelled automatically and the stored speed in the memory is erased.