Got my wife a 2008 Yukon XL 4wd to haul the kiddos around. So far has been an absolute piece of junk. A week after we got it, low oil pressure. Changed the oil sensor sending unit w/ ac delco part for Scoggin Dickey. Still low oil pressure. Looked at the dip stick, looked good. Looked under the truck, oil all over the oil pan and oil filter. Still not sure where the oil is leaking from but it's going to be fixed along with the AFM/DOD delete that some dipshit thought was a good idea.
Pulled the ....Ford Motorcraft filter off, changed the oil, no more low pressure.

Electrical nightmare...
Remote start wont work. Changed battery in the remote, still wont work, everything acts as if it should start. I hear the starter relay click, lights blink, but it wont start. There are no check engine lights. Sometimes the battery is dead in the mornings. I had the battery checked, it was 2 years old and bad. Three weeks later, it's dead again. Change the alternator since the alternator was dropping below 12V, even though it was about 2 years old. We'll if this problem continues. I also noticed that the engine hours reset to 0 after I changed the battery?
The driver door mirror mysteriously stopped blinking and the power adjust isn't working either.
The cruise control randomly cuts off when the car hits a bump. So today I changed the brake light switch. While I was changing the brake light switch, I noticed that the doors click like someone hits the door lock button about every 60seconds or so they'll click.
WTF!!?? Is this thing cursed?

 

Sounds like the normal battery cables with high voltage drops. They need to be factory ones and not your local best after market units. Perform a voltage drop on the poss cable and neg cable end to end, if voltage is more then 0.200mV they should be replaced. The generator was not bad I bet you there pulse with modulated and turn off when not needed for fuel economy. To perform voltage drop install a DVOM meter on one end of the poss and the other on the input of the underhood fuse block, hold the gas pedal to the floor and crank engine and measure readings. same the neg

 

I'm pretty sure the alternator was bad. Since changing it, the new one hardly falls below 14V. I drove it 1200 miles this week and so far it has only fallen below 14 a few times. Most likely for the same reason you stated, to save on fuel. The older one wasn't seeing 14V at first start up or within an hour after first start up. I noticed the alternator I removed was a replacement from Carquest.
From other trucks I have seen, the battery cables look to be OEM and most likely never replaced.
Are you still in Texas Jermoslin?

 

Yes, Longview. one other thing could be a shorted to ground High speed data circuit, most likely by brake pedal or transmission connector terminal backed out. And restart will not work if it has a stored codes. do you have any history codes stored. But test cables too

 

I'm in Midland now, came here from Rockwall. Before that, Wichita Falls.
I've had the truck for about 3 months now. No codes showing up on my HPTuners. What about the body control module? I may leave this scanner hooked up and see if any codes show up this week while my wife drives it to work and back. Pretty odd that it shows less then 50 hours but has 151,000 miles lol

 

Yeah body codes will disable remote start and "U" witch may be from Data circuit rubbing on ground, hood switch faults. I dont know if HP will show remote start disable data.

 

I have a 08 Suburban that had the same issues. I even put in a new battery and the next day the same **** happened. Found out It was the negative battery cable. At least it was for me.
a new cable from the stealership is like $70 bucks and will most likely do the same down the road. The cable snakes off from the battery terminal forward to the engine block and also to the forward frame.

I removed the negative cable..cleaned it up...and soldered the cable ends. 3 connections, battery terminal (-), engine block (terminal lug) and the frame (terminal lug). Solved all my problems.
If you look at the cable where it goes into the battery terminal mine was loose and a greenish color from corrosion. Hope that helps..I know I was pissed always having to go rescue my wife stranded somewhere.

 

Dude, leave the afm dod delete in it, that **** sucks anyways.
As far as oem power cables. Why in the beep beep would you put oem back on?

Do the big three setup and never think about cable issues again!
Zero guage or the fattest power wire you can get from a audio shop, solder the proper terminals on and heat shrink it.
If you want a black oem style, buy tek flex from amazon and shield the cables.

There is absolutly no reason to remove afm dod delete and go back to oem cables.


rempte start, is it oem or aftermarket?

As far as you bitching about these problems, You knew it was modded whn you bought it.

 

Sorry to hear about your pain. My 150k mile 08 Yukon has been pretty good so far.

 

It wasn't modded when I bought it, and it doesn't have the afm/dod delete yet. It's coming though lol and even if it was modded, the afm/dod delete doesnt have dick to do with the electrical problems that came two-three weeks after the purchase.