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.
• If a parking brake signal input to the 4-wheel drive (4WD) control module (CM) indicates, the module controls the torque transmitted to the rear 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/RSC Control

• If a signal from the dynamic stability control (DSC)/roll stability control (RSC) hydraulic unit (HU)/control module (CM) input to the 4WD CM indicates that Antilock Brake System (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/RSC 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.