Cruise Control: Description and Operation

Current is applied at all times through STOP LP fuse to TERMINAL 1 of the cruise control ECU TERMINAL 2 of stop light SW, and also through the ECU-B fuse to TERMINAL 15 of cruise control ECU.

With the ignition SW turned to ON, the current flows through GAUGE fuse to TERMINAL A-1, of cruise control indicator light (combination meter) and TERMINAL 4 of the A/T indicator SW (park/neutral position SW). At the same time, the current through ECU-IG fuse flows to TERMINAL 14 of cruise control ECU.

When the ignition SW is ON and the cruise control SW is turned ON, a signal is input from TERMINAL 5 of cruise control SW to TERMINAL 19 of cruise control ECU. As a result, the cruise control ECU functions and current flows to TERMINAL 14 of cruise control ECU to TERMINAL 13 of cruise control ECU--> GROUND, and the cruise control system is ready for operation.

At the same time, the current through the GAUGE fuse flows from TERMINAL A-1 of cruise control indicator light (combination meter) -->TERMINAL B-16 --> TERMINAL 7 of cruise control ECU --> TERMINAL 13 to GROUND, causing the cruise control indicator light to light up, indicating that the cruise control is ready for operation.

1. SET OPERATION
When the cruise control SW is turned ON and the set SW is pushed with the vehicle speed within the set limit (Approx. 40 kph, 25 mph to 200 kph, 124 mph), a signal is input to TERMINAL 18 of the cruise control ECU and the vehicle speed at the time the set SW is released is memorized in the ECU as the set speed.

2. SET SPEED CONTROL
During cruise control driving, the ECU compares the set speed memorized in the ECU with the actual vehicle speed input into TERMINAL 20 of the cruise control ECU from the vehicle speed sensor, and controls the cruise control actuator to maintain the set speed.

When the actual speed is lower than the set speed, the ECU causes the current to the cruise control actuator to flow from TERMINAL 12 --> TERMINAL 6 of cruise control actuator --> TERMINAL 7 --> TERMINAL 11 of cruise control ECU. As a result, the motor in the cruise control actuator is rotated to open the throttle valve and the throttle cable is pulled to increase the vehicle speed. When the actual driving speed is higher than the set speed, the current to cruise control actuator flows fromTERMINAL 11 of ECU --> TERMINAL 7 of cruise control actuator --> TERMINAL 6 --> TERMINAL 12 of cruise control ECU.

This causes the motor in the cruise control actuator to rotate to close the throttle valve and return the throttle cable to decrease the vehicle speed.

3. COAST CONTROL
During the cruise control driving, while the coast SW is ON, the cruise control actuator returns the throttle cable to close the throttle valve and decrease the driving speed. The vehicle speed when the coast SW is turned OFF is memorized and the vehicle continues at the new set speed.

4. ACCEL CONTROL
During cruise control driving, while the accel SW is turned ON, the cruise control actuator pulls the throttle cable to open the throttle valve and increase the driving speed.

The vehicle speed when the accel SW is turned OFF is memorized and the vehicle continues at the new set speed.

5. RESUME CONTROL
Unless the vehicle speed falls below the minimum speed limit (Approx. 40 kph, 25 mph) after canceling the speed by the cancel SW, pushing the resume SW will cause the vehicle to resume the speed set before cancellation.

6. MANUAL CANCEL MECHANISM
If any of the following operations occurs during cruise control operation, the magnetic clutch of the actuator turns OFF and the motor rotates to close the throttle valve and the cruise control is released.

* Placing the shift lever except "D" position or except "3" position. "signal input to TERMINAL 2 of ECU"
* Depressing the brake pedal (stop light SW ON). "signal input to TERMINAL 16 of ECU"
* Pushing the cancel SW (cancel SW ON). "signal input to TERMINAL 18 of ECU"

7. AUTO CANCEL FUNCTION
A. If any of the following operating conditions occurs during cruise control operation, the set speed is erased, current flow to magnetic clutch is stopped and the cruise control is released. (cruise SW turns OFF)

When this occurs, the ignition SW must be turned OFF once before the cruise SW will turn ON.
* When current continues to flow to the motor inside the actuator in the throttle valve "OPEN" direction.
* Motor does not operate despite the motor drive signal being output.
* Voltage input to cruise control SW [Comb. SW) is not normal

B. If any of the following conditions occurs during cruise control operation, the set speed is erased and the cruise control is released. (The power of magnetic clutch is cut OFF until the set SW is "ON" again.)
* Over current to transistor driving motor and/or magnetic clutch.
* Open circuit in magnetic clutch
* There is a brake or short in the potentiometer wiring
* Momentary interruption of vehicle speed signal.
* When the vehicle speed falls more than 16 kph (10 mph) below the set speed, e.g. on an upward slope.
* short circuit in cruise control SW

C. If the following condition occurs during cruise control operation, the cruise control is released.
* When the vehicle speed falls below the minimum speed limit, approx, 40 kph, (25 mph)
* Open circuit for TERMINAL 1of the cruise control ECU and TERMINAL 2 of the stop light SW.
* The motor has stopped due to low voltage

8. AUTOMATIC TRANSMISSION CONTROL FUNCTION
* In overdrive, if the vehicle speed becomes lower than the overdrive cut speed (set speed minimum approx. 4 kph, 2.5 mph) during cruise control operation, such as driving up a hill, the overdrive is released and the power increased to prevent a reduction in vehicle speed.
* After releasing the overdrive, if the vehicle speed becomes higher than the overdrive return speed (set speed minimum approx. 2 mph, 1.2 mph) and the ECU judges by the signals from potentiometer of the actuator that the upward slope has finished, overdrive is resumed after approximately 6 seconds.
* During cruise control driving, the cruise control operation signal is output from the cruise control ECU to the engine control module, upon receiving this signal, the engine control module changes the shift pattern to normal, to maintain smooth cruise control operation (on a downward slope etc.), lock-up release of the transmission is forbidden when the idling point of the throttle position is "ON".