I'm going to try to say something here without being called Mr. Negativity.
The person that sold this vehicle, sold it for a reason. The custom installs that were done on this vehicle were not done by a real professional - it was done by a butcher who had these great idea's and very little skill level and was not willing to pay anyone to set things straight.
When you mess things up as bad as what they are in your vehicle, after a few things are done wrong and some error codes goes off, the vehicle tends to get defensive and tries to fight off the so called improvements that the previous owner did - kind of like your body trying to fight off the flu.
The noise you hear in the door is the Body Control Module
The gauges might or might not even be at fault. There is no automatic repair that says 100% of the time when you have a problem with the gauge - that it is the stepper motor.
Now I didn't research this far enough to know if this vehicle's all wheel drive unit sends the speed information from a sensor in the transfer case or not.
But there are times when there is problems that is in the transfer case that appears to be speedometer related.
I would suggest either finding someone who does power tuning and have that person look at this vehicle and diagnose all the problems before you start to throw good money after bad at it.
The other thing is - why did you buy it? Didn't you even look at it before you bought it? Did you think that all those things that were wrong were easy fixes and that the previous owner was a dumb ass and didn't know what he had or didn't know what he was doing and that you knew more then he did and figured that you could just take it home and wrap some duct tape over the wires and everything would work? I mean - come on now. Nobody could be that dumb to believe that you could just hack a vehicle up that bad and not have problems.
Custom installs costs thousands of dollars. Even when they are done wrong.
Most times when something is done wrong, other things stops working.
Things like the self dim in the mirrors. So the person that owned the vehicle probably thought that alll he needed to do was change the glass and everything would be a ok. Only when he found out how much stuff costs to replace and even when he tried to replace it - it didn't work, then he just decided to dump it off on some sucker and move on with his / her life.
The most emotional thing about all this is that you never know when the theft lock / Security is going to go off and then the vehicle is going to stop running and you are going to be left someplace. I don't think that it is a question of IF, it is a question of WHEN!
I would take it to a Chevrolet Garage and see how much of the damage they can fix with the TECH II. maybe it is beyond repair - if it does not have the stock radio and stuff. Either way, maybe they can turn some things on and shut some things off and diagnose some of the problems and replace one or two of the modules that I think are probably faulty.
Good Luck with your new truck. I will be praying for you - that your wife makes it home ok while she is driving it.
