4WD SYSTEM CONTROL OPERATION

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Normal Control

• When starting off or accelerating during straight-ahead driving, torque transmitted to the rear wheels is optimally controlled to ensure sufficient acceleration performance. Due to this, standing-start and acceleration performance is improved.

• Also, in order to improve fuel economy when driving at a stable, consistent speed, torque transmitted to the rear wheels is damped, and rear-wheel drive is controlled to maintain it close to that of the front wheels.

Tight Cornering Control

• When the 4WD CM determines, based on the four-wheel speed signal, that the vehicle is in tight cornering, it reduces the torque transmitted to the rear wheels to avoid tight corner braking characteristics.

Integrated DSC Control

• If a signal from the DSC HU/CM input to the 4WD CM indicates that ABS control is activated, the module controls the torque transmitted to the rear wheels to prevent undue influence on ABS control.

• Also, when a coupling torque request signal is received from the DSC HU/CM, the module controls the torque transmitted to the rear wheels to match the amount of requested torque.

Other Control

• In case the rear differential oil temperature exceeds the specified amount, or when there is an unusually large variation in the rotation speed of the front and rear wheels (ex. when trying to get unstuck), control is temporarily suspended in order to protect the 4WD system. When this occurs the 4WD warning light flashes to indicate the situation to the driver.