Instrument light display adjuster wheel function
 

I was having trouble reading the instruments in the daylight and I was oblivious to the fact that there was an adjuster wheel to brighten the readout. That is resolved, but what is the function when the wheel is maxed out? It hits a spot where resistance is felt then feels like it should switch something on; old timers will recognized that traditionally that is how the dome light is turned on in American cars, but not here unless something is broken. Yes...dome light is not burnt out, is set to Door, and no, I do not have the Owner's Manual (2004 ES).

Hello,

Here is an Owners Manual for your car.

That Switch position in the dial locks the Max brightness on the dash even when the headlights are on, could be useful when you need to have the headlights on during daylight, in places like tunnels for example.

Hope this helps and best of luck!