Construction of Cruise Control System


1.Cruise control ECU
The ECU receives signals from the vehicle speed sensor and various switches, and processes them according to a pre-stored program.
Based on these signals, the ECU sends control signals to the actuator.
It also has a special circuit that allows the technician to conduct the system diagnosis and check the operation of the input and output signals using the power indicator light in the combination meter.
2.Cruise control actuator
The actuator plays an important role in the CCS.
The actuator consists of a motor, magnetic clutch, and potentiometer.
In accordance with the instructions from the cruise control ECU, the actuator increases and decreases the throttle valve-opening angle.
There used to be a vacuum-driven type.
3.Main and control switch
(1)Main switch
The main switch is the main power switch for the CCS. It is a push-button switch and power supplied to the system is turned on and off every time the switch is pushed into main switch.
In some models, turning ignition switch off turns main switch off. Even if turning the ignition switch on the again the main switch remains off.
(2)Control switches
The control switches are on a stalk lever. They control five different functions (SET, COAST, RESUME, ACCELERATE, CANCEL) when the vehicle is driving in the cruise control mode. The SET and COAST modes are on one switch and the RESUME and ACCEL modes on another.
A switch goes on only when operated in the direction indicated by arrows [1], [2] and [3], and goes off when released.
The switches are automatic return type switches.
4.Speed sensor
The function of the vehicle speed sensor is to keep the cruise control ECU informed of the current vehicle speed.
As the vehicle speeds up, the speed sensor revolves faster and the frequency of the speed signal becomes higher. As the vehicle slows down, the frequency of the speed signal becomes lower.
Thus, the speed sensor increases or decreases the vehicle speed signal.
The speed sensor transmits the pulse signal from the transmission to the cruise control ECU via the combination meter.
Recently, the system that receives the vehicle signal from the speed sensor via the ABS ECU and combination meter is mainly used.
5.Cancellation switches
The cancellation switches consist of the control switch, the clutch switch, the neutral start switch, and the stop light switch.
When any of these switches turn on, the cruise control is temporarily cancelled.
However, the set speed is stored in the memory of the cruise control ECU as long as vehicle speed is higher than 40 km/h [25 mph].
Therefore, the last set speed is restored automatically when the resume switch is turned on.

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