GENERAL INFORMATION

FEATURES

The Active Stability and Traction Control System (ASTC) has been installed.

The Active Stability Control System controls four wheels brake force independently and also reduces engine power to manages spin or drift-out when driving near to vehicle limits.
The Active Traction Control System controls four wheels brake force independently and also reduces engine power to prevent excessive wheel spin and enhance vehicle stability on slippery surfaces. It also improves driving ability on poor surfaces to apply brake force to spinning wheel. The effect is as well as differential lock.
Fail-safe function ensures safety is maintained
Improved serviceability

To shorten the lines and enhance data transmission reliability, communication with other ECU is performed over a CAN (Controller Area Network).

note

To prevent the driving force loss and to generate secure braking force, vehicles with rear differential lock prohibit the Active Stability Control System control, the Active Traction Control System control and the ABS (EBD) control while the rear differential lock is operating or being switched.
For further details on CAN communication, refer to GROUP 54D, CAN .
The ASTC-ECU controls ABS as well.

CONSTRUCTION DIAGRAM

Component		Number	Outline of functions
Sensor	Wheel speed sensor	1	Sends alternating current signals at frequencies which are proportional to the rotation speeds of each wheel to the ASTC-ECU.
	Stoplamp switch	2	Sends a signal to the ASTC-ECU to indicate whether the brake pedal is depressed or not.
	G and yaw rate sensor	3	It detects the lateral acceleration and longitudinal acceleration and yaw-rate of the vehicle. Then it sends a signal through the CAN bus line to the ASTC-ECU.
	Steering wheel sensor	4	Detects the steering wheel angle, and sends a signal to the ASTC-ECU through the CAN bus line.
	ASC OFF switch	5	Sends a signal to the ASTC-ECU to turn on and off the active stability control.
	2WD/4WD detection switch	6	Detects the transfer driving mode.
	4LLc detection switch	7
	Centre differential lock detection switch	8
	2WD detection switch	9
	4H detection switch	10
	Rear differential lock switch^*	11^*	Sends the rear differential lock state to ASTC-ECU.
	Master cylinder pressure sensor	12	Informs the ASTC-ECU whether the brake pedal is depressed (the same function as a stop lamp switch)
Actuator	Hydraulic unit	13	Drives the solenoid valves according to signals from the ASTC-ECU in order to control the brake hydraulic pressure for each wheel.
	Valve relay	14	It is turned on/off by the signal from the ASTC-ECU. ASTC-ECU shuts down the solenoid valves by this relay, when malfunction is detected.
	HBB motor relay	15	Is turned on by the signal from the ASTC-ECU, and energizes the motor in the HBB.
	HBB buzzer	16	Sounds by a signal from the ASTC-ECU to inform the driver of the Active Traction Control system overheat. HBB buzzer is also used for accumulator low-pressure warning.
	Brake warning lamp	17	Illuminates in response to signals from the ASTC-ECU when a problem which affects the HBB and EBD function develops in the system.
	ABS warning lamp	18	Illuminates in response to signals from the ASTC-ECU when a problem develops in the system.
	Active stability control indicator lamp	19	It receives a signal from the ASTC-ECU, and indicates ASC or ATC system operating and system status. Flashes: ASC or ATC system operating. Illuminate with buzzer: ATC system is in overheat protection mode. Only illuminate: ASC or ATC system has malfunction.
	Active stability control-OFF indicator lamp	20	Receives a signal from the ASTC-ECU, and flashes or illuminates to inform the driver that the system is not operating or defective.
	4WD indicator lamp	21	Receives a signal from the ASTC-ECU, and flashes to inform the driver which wheel is under the active traction control.
Diagnosis connector		22	Sets the diagnosis codes and allows communication with the M.U.T.-III.
Engine-ECU <M/T>		23	Receives a signal from the ASTC-ECU to control the engine output.
Engine-A/T-ECU <A/T>		24
Active Stability Control and Active Traction Control System control unit (ASTC-ECU)		25	Controls actuators (described above) based on the signals coming from each sensor.
			Controls the self-diagnosis and fail-safe functions.
			Controls the diagnosis function (M.U.T.-III compatible).

note

^*:Vehicles with rear differential lock (Option)