I just took mine out because for one they fade and then look like shit two the tach light went out and I could not see where the needle was.
Mine where wired directly to the dimmer knob. So you could turn down the brightness abit. Most of the gauges havethat little swicth pad that changes colors and controls how bright they are. Make sure to solder them in and then wrap with electrical tape. No other tape with do, most with dry out and fall off. If that happens and the leads touch you could start an electircal fire in your dash. Fun Fun Fun!!!