How to activate the RevLeds or flag leds on my Wheel?

RevLeds (RPM LEDs / RPM led indicators), flag leds are primarily controlled by the game or simulation software. Since those LED features, as well as the RevStripe (on other Steering Wheels), and extended display or force feedback functions, rely on signals from the racing simulation, functionality of these features is fully dependent on support from the game - at least on consoles.

To answer your question more specifically, it would be important to know which Wheel Base + Steering Wheel combination you are using, on which platform you are playing, and which game you are driving.

On PC, there are additional applications to activate or tune the RevStripe and other features on the steering wheels. For example, Fanatec offers Fanalab which brings a bunch of tools to effectively control, adjust and use such extended features. In the driver control panel you can do a basic functionality test. Other and similar options worth mentioning would be FanaLeds or Ledsmaster.

Since such programs are not possible on PlayStation and Xbox, the games and their developers need to provide support for these LED functions. Fanatec cannot directly implement such features into games; this needs to be done by the studios. A "slight push" from the community can often be very helpful in showing game producers that these features are valuable to their customers. We suggest checking the game forums or contacting the development studio to express that these features would be greatly appreciated.