TCS function: Notes
The TCS function in the TC/ABS control module employs both reduction of engine torque and brake application on the driving wheels in order to utilize the friction of the road surface in all driving conditions.
To understand the TCS function it is best to assume that the road surface is slippery, with varying degrees of friction under the two drive wheels.
The rotational speed of the rear wheels is used as a reference for comparing the speed of the drive wheels individually. When either of the drive wheels rotates at a higher speed than the rear wheels, this is described as wheelspin. The magnitude of this wheelspin and the speed of the car are decisive for the manner in which the system works.
The system prioritizes traction at low speeds and initially provides control using the brakes. The purpose is to brake the drive wheel with least grip (the first wheel to spin).
This allows more power to be transferred to the other drive wheel, which then has maximum traction. Through this distribution of the power applied to the wheels, the available friction can be utilized to maximum effect.
At higher speeds, priority is given to the transfer of lateral force so that steering control is maintained. The system then works primarily by limiting engine torque.
To retain a the car's sporty feel, even on slippery surfaces, and to utilize the available grip, a certain degree of wheel spin is always permitted. The amount of spin varies with vehicle speed and road grip.
If the driver brakes during TCS modulation, the TCS function with brake application will be turned off and the braking function will be chosen. The TC/ABS control module will continue with TCS modulation using engine torque limitation.