2017 Yukon XL SLT Dash says Charging problems and everything goes nuts

[salisburyv]

and just because the grounds are tight does not mean they're good. what color are they? is it a light blue/green? that's corrosion. it'll get between the ground points and render them less effective. I cleaned all the mounting surfaces, and then treated the area to reduce the chance of it happening again. super-lube anti-corrosion and connector gel. works pretty good. if you bought the alt recently they should exchange it without issue. let us know plz

 

[Tahoe14]

If you have not had your extended warranty that long you could cancel it, receive a refund and get a good one.

 

[sealandsky]

I am up underneath it as we speak, checking for loose ground wires. I have found a few but they are all snug or tight so far. I’ve got the one coming off the battery to the engine block, I found one underneath drivers door connected to body mount Bracket. I’m sure there’s probably about 100 more or I’m just slowly looking for them. I think I’ll take this alternator off before 7 AM and maybe I’ll get a chance to run it and get it checked out that should still be under warranty. I put a voltmeter on it this morning And it showed about 11 1/2 V. Then I started it, went from 13.5 V down to about 7 pretty rapidly

Don't just make sure the grounds are tight - Remove them, clean the contact area, then reinstall. Grounds are everything on these vehicles.