It's basically every light that you can think of that dims when you turn the lights on. So.. it's every light in the Gauge Cluster with the exception of the warning lights.. so - that would be all the back-lights, the odometer light, the back lights that tell you what gear you're in, etc. The clock backlight, the heating control backlights, the lights in my button cluster with fog light switch, sunroof, traction control. My headunit dims when the lights turn on, but it's an aftermarket radio with it's own power source.

However, the indicators for the fog lights, defrosters, etc. all work if that device is turned on at the time.