'05 Dodge magnum RT advice

[Desbel42]

Hey all. I recently purchased a 2005 Dodge Magnum RT 5.7 HEMI AWD All and all the car runs great and for the price I paid for her, I felt she was worth buying even with the known issues. So, first off, the previous owner felt the need to hook up all this...extra stuff. They had pulled out the dash, installed a cheap cd/mp3 player, light bars on the inside and out that are customizable, ran a cellphone charger through the dash and installed subwoofers. Cool I guess. When it came time to finish up, he didn't. Left the wiring hanging out, put a Chrysler 300 dash frame back on for some reason and never did anything else. The seller assumes that because of his...tinkering, he caused some  issues. The backlight to the cluster doesn't work. Gas gauge doesn't work etc. But the biggest one seems to be that the esp/bas light continually comes on. But it doesn't come on randomly, it comes on after you try to put the pedal to the medal and for some reason the tires sort of lock up, lurches looses a bit of power but doesn't die. You let up and it's perfectly fine. Idles and drives perfect everytime. I hooked it up to a reader and it pulled 9 codes; U0002, P2638, U1402, U0121, U0103, U0100, U0155, U110b, U0164. I haven't researched them extensively, but so far they all seem to be a loss of communication and to check the wiring. I know that the wiring in most cars is a pain, but to have no idea what's been changed or rewired or whatever the guy did is frustrating to just think about. So finally...sorry for the long post, my question is, should I just get the entire car rewired? New harness and the works? Or should I try to individually figure out each issue on its own. I come from a car savvy family, my dad and uncle built and raced there own cars but electrical issues was never a strong point. I'm confident in my mechanical abilities but electrical? Not even the slightest clue where to even start. If someone could just point me in a good direction to start would be awesome and any advice is greatly appreciated. Thanks for taking the time reading my extra long post. Hopefully I can get this awesome wagon back up to where she should be.