DYNAMIC TORQUE CONTROL 4WD/AWD SYSTEM SYSTEM DESCRIPTION

SST
A00YUPH 09843-18040 Diagnosis Check Wire No. 2

  1. GENERAL DESCRIPTION

    The dynamic torque control 4WD/AWD system detects the driving conditions based on signals from each ECU, each switch, the steering angle sensor*2, the wheel speed sensor, the deceleration sensor*1, and the acceleration sensor*2. The system controls the electronic current passing through the linear solenoid of the electromagnetic coupling, and performs electronic control to distribute the optimum torque to the rear wheels.


    • *1: w/o VSC

    • *2: w/ VSC

  2. FUNCTION OF MAIN COMPONENTS

    Component Function
    Combination Meter Assembly 4WD/AWD Warning Light*1

    • Illuminates to warn the driver of a malfunction in the dynamic torque control 4WD/AWD system.

    • Blinks to inform the driver of the DTCs in diagnostic mode.
    AWD Warning*2 Displays a warning to the driver when the system malfunctions.
    4WD/AWD Lock Mode Indicator Light

    • Illuminates to inform the driver of the lock mode control status.

    • When lock mode is turned ON, the indicator light blinks twice and then remains illuminated.

    • When lock mode is turned OFF, the indicator light turns off.
    Sport Mode Indicator Light*3 Illuminates to inform the driver of the sport mode control status.
    Speed Sensors (4) Detect the wheel speed of each wheel.
    Crankshaft Position Sensor Detects the engine speed and outputs it to the ECM.
    Throttle Position Sensor Detects the throttle valve position and outputs it to the ECM.
    Park/Neutral Position Switch Assembly*6 Detects the shift position of the transaxle and outputs it to the ECM.
    Stop Light Switch Assembly Detects when the brake pedal is depressed.
    Parking Brake Switch Assembly Detects when the parking brake is applied.
    Steering Angle Sensor (Spiral with Sensor Cable Sub-assembly)*5 Detects the turning of the steering wheel.

    Deceleration Sensor*4

    Acceleration Sensor (Airbag Sensor Assembly)*5

    		 Detects the vehicle's longitudinal acceleration and deceleration.
    Transfer Drive force input into the differential is redirected 90 degrees and output to the propeller shaft by the transfer.
    Rear Differential

    Transmission Coupling Assembly


    • 4WD Linear Solenoid

    		 Distributes drive torque in accordance with the amperage applied by the 4WD ECU assembly.
    4WD ECU Assembly Controls the amperage applied to the 4WD linear solenoid based on signals provided by the sensors in order to optimally distribute drive torque in accordance with driving conditions.
    ECM Outputs signals such as the shift position signal, throttle position signal, and crankshaft position signal to the 4WD ECU assembly.
    Skid Control ECU (Brake Actuator Assembly) Outputs signals such as the vehicle speed signal and deceleration signal*4 to the 4WD ECU assembly.
    Main Body ECU (Multiplex Network Body ECU) Outputs signals such as the parking brake switch signal and ambient temperature signal to the 4WD ECU assembly via CAN communication.
    Transmission Coupling Assembly Distributes torque to the rear wheels based on the amount of current sent from the 4WD ECU assembly.
    4WD/AWD Lock Switch (Differential Lock Switch) Switches between auto mode and lock mode.
    Sport Mode Switch (Combination Switch Assembly)*3 Switches between normal mode and sport mode.

    • *1: for Segment Display Type

    • *2: for Dot Display Type

    • *3: for Manual Transaxle w/ Sport Mode

    • *4: w/o VSC

    • *5: w/ VSC

    • *6: for Automatic Transaxle or for CVT

  3. DRIVING FUNCTION

    Control Function
    Starting Control Controls torque distribution to the rear wheels to ensure traction performance when starting off and to avoid the occurrence of tight corner braking phenomenon* when turning.
    Normal Control

    Controls torque distribution to maintain stability while cornering and acceleration performance when accelerating straight ahead.

    Reduces torque distribution to the rear wheels when driving is judged to be stable to improve fuel consumption.
    Sport Mode Control Determines the driver's steering operation and the vehicle condition using signals from each sensor, and optimizes torque distribution to the rear wheels in order to maintain cornering stability and maneuverability.
    Control when Locked Controls torque distribution to the rear wheels to allow maximum traction performance.
    Engine Torque Control May limit engine output if there is a possibility that the drivetrain could be damaged by overdriving.
    Safety Control

    May stop 4WD/AWD control and set the front wheels as the drive wheels if a malfunction is detected in the dynamic torque control 4WD/AWD system or other related systems, and warns the driver.

    Stops 4WD/AWD control, sets the front wheels as the drive wheels and warns the driver if there is a possibility that the drivetrain could be damaged.

    • *: Tight corner braking phenomenon: a phenomenon in which a 4WD/AWD vehicle may lurch and decelerate due to a rotational speed difference between the front and rear wheels, such as during low-speed cornering in 4WD/AWD mode.