Electronic systems in cars play a number of roles. They are responsible for the most basic functions, such as turning on the interior lighting, illuminating the door handles and the dashboard, controlling the interior temperature (hot and cool air), controlling the engine, as well as for supporting the braking and steering systems. They cooperate with numerous sensors and use control modules that cooperate with one another. A failure or wrong operation of a single element affects the operation of an entire electronic system. In the case of most modern cars, a failure of an electronic system is signalled by a warning light on the dashboard.