Traction Control System (TCL)

GENERAL DESCRIPTION
If the throttle is opened excessively when a vehicle is started or accelerated, the driving wheels may slip due to excessive drive torque. This adversely affects startability, accelerating ability or controllability. To ensure startability, accelerating ability and controllability, this TCL system will prevent wheel slip by controlling (applying) brake fluid pressure to the drive wheels to adjust the driving torque according to road conditions. Each wheel-speed sensor detects wheel speed and converts it to an electric signal. The ABS-ECU determines which wheel begins to slip according to that signal. If the ABS-ECU determines wheel slip, it activates the solenoid valves and the pump inside the hydraulic unit to prevent the wheel slip by applying brake ensuring controllability. This TCL system is controlled by the ABS-ECU, and the TCL components are shared by the ABS system. If the ABS hydraulic unit is faulty, the ABS-ECU must be replaced.

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CONSTRUCTION DIAGRAM

System Check Sound
When starting the engine and moving the vehicle for the first time after start-up, a thudding sound can sometimes be heard coming from the engine compartment. This is a normal sound during the ABS and TCL unit self-check.

ABS Operation Sounds and Sensations
During normal operation, the ABS makes several sounds that may seem unusual at first: A whining sound is caused by the ABS hydraulic unit motor.