I installed LEDs for the front & 2nd row floorboard areas. They're the LEDs I got from HIDGuy for my vanity lights. I could never get them to work correctly with the rest of the dome light setup. I have a voltage issue in my dome light system, which I think is a bad dimmer/on-off switch... I guess. I gave up on that and put the OEM vanity lights back in. No issues any longer. (just to be clear, it's not his lights causing the problem. I have lights from superbrightleds.com that did the exact same thing, I just used his for my custom setup because they are freaking bright)
I had originally designed it so the Floorboard lights would turn on and off with the main domes, but when they would come on ALL of the LEDs were about 20% brightness. I instead installed a rocker switch down under the dash on the driver's side so they can be operated independently from the domes. The rocker is completely hidden, and had its own in-line fuse. The wiring is all heat shrunk together into a nice clean harness, and run under the heat delivery tube up front, and under the center console and mounted under the seats for the 2nd row.
It's a nice thing to have when a toddler drops their drink or their toy on a long trip, and you gotta find it before they lose their minds and go *******.
(you young bloods out there just wait!)
BH