What you should say is that TCS turns off the light. 1.8 car is equipped with TCS traction control system, and there is a TCS off button on the left side of the steering wheel. When pressed, the TCS OFF light will light up, indicating that the TCS function is turned off.
If you don't press that button, the TCS OFF light will light up, indicating that the system is faulty and needs to be overhauled. It may be that there is something wrong with the circuit or TCS control unit.