A traction control system (TCS), in German known as Antriebsschlupfregelung (ASR), is typically a secondary function of the anti-lock braking system (ABS) on production motor vehicles, designed to prevent loss of traction of driven road wheels. TCS is activated when throttle input and engine torque are mismatched to road surface conditions.
Intervention consists of one or more of the following:
- Brake force applied to one or more wheels
- Reduction or suppression of spark sequence to one or more cylinders
- Reduction of fuel supply to one or more cylinders
- Closing the throttle, if the vehicle is fitted with drive by wire throttle
- In turbocharged vehicles, a boost control solenoid is actuated to reduce boost and therefore engine power.
Typically, traction control systems share the electrohydraulic brake actuator (which does not use the conventional master cylinder and servo) and wheel speed sensors with ABS.