First introduced in 1998, to the end of 2000s ATC (Active Torque Control) was the main type of all-wheel drive - without center differential, automatic connection of the rear wheels by electromechanical coupling mounted on the rear differential carrier.
Electromechanical coupling assembly is mounted to the differential carrier. The outer parts of the main clutch and control clutch are coupled to the front housing, the inner part of the main clutch - to the shaft, the inner part of the control clutch - to the cam. The control clutch - multiple metal plate type, the main clutch - multiple wet plate type.
If the solenoid is not energized, thecontrol clutch is not engaged - the drive force is transmitted from the propeller shaft to the front housing is not transmitted to the rear wheels.
When the solenoid is energized by control unit, the armature is attracted to the control clutch to engage it. This causes the cam to rotate and rotational movement of the cam causes the piston to push and engage the main clutch. The drive force is transmitted from the front housing to the rear wheels. The amount of transmitted drive force is controlled steplessly by controlling the amperage applied to the solenoid - the higher current amperge means the greater piston stroke.
ATC is controlled by ABS control unit or for later models, by separate control unit. The system uses wheel speed sensors, steering wheel position sensor, acceleration sensor, signals of throttle position, engine speed, range, brake pedal and parking brake.
Type 1: With "AUTO" button - modes "AUTO 4WD" and "2WD". At OFF state there is only front-wheel- drive, at ON state - control unit automatically manage torque distribution to the rear wheels.
Type 2: With "LOCK" button - modes "AUTO 4WD" and "LOCK". In AUTO mode control unit automatically manage torque distribution to the rear wheels, at LOCK mode - maintains the highest possible rate of electromechanical coupling locking.