Here you see a very well lit dash, however my dash (S4) is not that bright at all. My numbers at the very most are lit, and that is on both of my FC's... however my second one until recently seemed as if there was extra lights helping.

 

Have you tried playing with the dash dimming switch? If not, check your voltage coming out of the alternator.

 

I have checked the dimmer, obviously.

The power coming from the alternator is fine. I believe it is the dash cluster unit, or whatever it is called. I did have more then proper lighting for a while, and then switched it out with my old cars and had the same problem. I switched it though because my speedometer meter was just hanging and reading my speed.

 

Are your bulbs in the back of the cluster working?

 

What bulbs are they? I switched all the bulbs from my working gauge cluster to the one I switched it out with, and yet no lights like there was.