Totally weird man. I never disconnect my batteries either when doing HU installs but ive done it for so long I can do it and never pop anything. But as for your issue, IDK man, Ive never even heard of that.

Do you think it is something in the custom tuning itself?

 

did you use a wiring harness on the HU or hard wire?
my 05 had 2 ACC/ON and 2 constant 12v wires going to my HU. my Hu only had one of each so i connected the 2 ACC/ON to the HU's ACC/ON and the 2constant 12v to the constant on on the HU.
as stated before i believe these trucks use the radio to route some power to other parts of the truck

(not very good at explaining stuff lol so if you dont get it i'll try to writ this again lol)

 

good point I had a malibu a few years ago that when the radio was unplugged the door chime, air bags, and dome lights didnt work.

 

hmm thats a great point. when i pulled the old system out i removed the headunit just to get it out of the way. I used a harness, and like you said it was 2 wires for each (acc and constant). When putting it back together I didnt remember there being two wires, so i called tech support. The broski said I only needed to connect one of them, so i did. That could very well be my problem. I wont be able to check it until tomorrow, so i'll post back when i figure something out.

 

you hit the nail on the head buddy. Thanks a ton. I had a 12v wire that wasnt connected (per instructions from tech support guy). As soon as I connected it, all the lights came on and the door started chiming. all problems have been fixed. thanks again to all for your ideas!

 

glad to help a brother out, i;ve learned so much from this forum and i'm glad i can start giving back.