Traction Control function

Monitors and controls wheel spin in the driving wheels at lower speeds in order to increase forward movement. If a wheel starts to spin that wheel is automatically braked so that the drive power is transferred to the other wheel. Activated only at speeds up to approximately 40 km/h (25 mph). When the traction control has been activated it can be used up to 80 km/h (50 mph). Traction control can be likened to an electronic limited slip differential.

Traction control is always connected after starting but can be deactivated using a switch. If the driver depresses the brake when the system is operating the function is deactivated.

The control module monitors how hard the traction control is working and calculates theoretical brake temperature. If there is a risk of the brakes overheating the function is deactivated. At the same time the warning lamp and a diagnostic trouble code is stored. When the brakes have cooled the warning lamp goes out and the function is reactivated, but the diagnostic trouble code (DTC) is still stored in the memory.

NOTE: This diagnostic trouble code (DTC) can also be stored if the brakes have had to work hard.

In cars with Traction control the ABS hydraulic modulator contains the following components: hydraulic valve (1), solenoid valve (2), and a by-pass valve (3), 2 of each, 1 per circuit.

There is a central valve in the hydraulic cylinder primary cylinder. The valve is normally open and ensures that the pump receives sufficient brake fluid during traction control (TC) operation.

The function is similar to the TRACS in the X70.