No Instrument lights and lose radio display when the head lights or parking lights are turned on. I searched and search and found the answer on another forum. A guy posted the exact same issues I was having with the dash lights and radio display. He replaced the head light switch, which seamed to work perfectly. Well I couldn't verify the dash light dimmer... So I bought a brand new switch, installed it and problem solved! Everything works including the dimmer. I did trouble shoot this completely also, tried the fuse, pulled it, replaced it, checked continuity on every fuse in the truck. I heard of problems from people installing after market stereos, hacking wires... none of that on my truck, checked every plug connection I could find, grounds too...it was the head light switch.