How does led technology works?
In electronics, the basic LED circuit is an electric power circuit used to power a light-emitting diode or LED.
The simplest such circuit consists of a voltage source powering two components connected in series: A current limiting resistor (sometimes called the ballast resistor), and an LED.
Optionally, a switch may be introduced to open and close the circuit. The switch may be replaced with another component or circuit to form a continuity tester.
Now check how this technology was implemented by Audi.