OFF-ROAD TRACTION ASSIST

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Outline

•  The Off-Road Traction Assist is a function to assist in freeing tires that are stuck when driving on rough ground (such as gravel roads or snow-covered roads).
•  The driver can switch the system to operational or non-operational using the Off-Road Traction Assist switch.
Caution
•  Do not drive the vehicle with the Off-Road Traction Assist operating under any of the following conditions. Otherwise, powertrain related parts could be damaged.
―  When driving on paved roads
―  Tires other than specified size are installed
―  Temporary spare tire is installed
―  Tire chains are installed
•  Avoid using the Off-Road Traction Assist continuously. If continuously used, the system may stop operating to protect the electronically controlled coupling component and the 4WD warning indication may flash. (See 4WD WARNING INDICATION.)
Note
•  When the Off-Road Traction Assist is operating or operable, vehicle vibration or booming noise may occur, but this does not indicate a vehicle malfunction.

Structural View

•  The Off-Road Traction Assist switch is located on the cluster switch and the Off-Road Traction Assist indicator light is located in the instrument cluster. (See OFF-ROAD TRACTION ASSIST SWITCH, OFF-ROAD TRACTION ASSIST INDICATOR LIGHT.)
•  Other component parts/modules of the Off-Road Traction Assist are common with those of the TCS control and 4WD control. (See TCS CONTROL.)(See 4-WHEEL DRIVE SYSTEM.)
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Function

•  When the Off-Road Traction Assist is operating, the TCS control and 4WD control are switched to the modes that prioritize assuring the driving force on rough ground. Each control changes as shown in the following table.

Control

Change detail

Reference
TCS control
Brake control
•  Increases braking force to spinning wheels
Engine torque control
•  Cancels engine torque reduction request
(See TCS CONTROL.)
4WD control
Coupling control
•  Increases torque distribution to rear wheels
(See 4-WHEEL DRIVE SYSTEM.)


Operation


Off-Road Traction Assist control

•  If the vehicle is stuck (1) when driving on rough ground (such as if diagonally opposed wheels lose contact with the ground), the Off-Road Traction Assist increases the brake fluid pressure on the spinning wheels to prevent wheel spin (2). It also stops the engine torque reduction control by the PCM and controls the output current to the electronically controlled coupling component to increase the driving torque distribution to the rear wheels (3). In this way, the driving force for the wheels on the ground is assured (4) to achieve enhanced ability for freeing the stuck vehicle from rough ground.

Off-Road Traction Assist operating

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Off-Road Traction Assist stopped

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Off-Road Traction Assist control conditions

Off-Road Traction Assist operable
•  By pressing the Off-Road Traction Assist switch when all of the following conditions are met, the Off-Road Traction Assist becomes operable. When the Off-Road Traction Assist becomes operable, the Off-Road Traction Assist indicator light in the instrument cluster turns on.
―  DSC HU/CM and PCM are normal
Off-Road Traction Assist operation conditions
•  The Off-Road Traction Assist operates when it is operable and all of the following conditions are met.
―  Vehicle speed is 35 km/h {22 mph} or less
―  Slipping drive wheel is detected
Off-Road Traction Assist stop conditions
•  When the Off-Road Traction Assist is operable and all of the following conditions are met, the Off-Road Traction Assist stops. When the Off-Road Traction Assist stops, the Off-Road Traction Assist indicator light in the instrument cluster turns off.
―  Off-Road Traction Assist switch is pressed
―  Ignition is switched OFF
―  DSC HU/CM or PCM detects malfunction