I'm having a bunch of issues with my 2006 yukon XL with the 5.3 and no one I've talked to can figure it..


It would start and run fine until one day it decided not to start in a car wash bay. I figured out that there was an ignition fuse under the hood that wasn't getting power right next to the fuel pump relay I have to jumper with a copper wire. I jumpered it with the fuel pump relay and that works a little too well.. the key no longer shuts the truck off, I have to obviously pull the fuel pump wire out and the one connecting the fuse. Then one day i stopped at a gas station and decided to make sure all the fuses were good and the right ones, so i took them all out one by one then forgot which fuse was not working so i wasnt able to get the truck to start and it was tiwed and parked for a few months at a friend's place with the driver window half open and sunroof vented during the last part of winter into spring.


Now I can't get the heater to shut off without disconnecting the battery. when the truck is running the heat controls aren't lit up and the buttons don't work. It's always blowing even when the truck is off to the point it blows cold and the battery slowly dies... I pulled everything to do with HVAC when the truck was off and nothing turned it off..


There's other things it just started doing too,( I have no idea if it's all related ):


Driving it started doing this thing when it almost dies and then starts going again for a second and doesn't get over 20Km/h like vroom die vroom die sorta thing until I slow down too much and it stalls..



The fog light button turns the headlights on and the radio off (I don't have fog lights hooked up

) and turning the headlight switch on manually turns the radio off


The heated seats don't work unless the driver seat is moving back and forth, as soon as the seat stopps in any position both seats click off


the sunroof was replaced and the button did work but it stopped working so its stuck vented open ..


Sometimes the doors will randomly lock and unlock when I'm sitting in the driver seat like it's possessed or something, I don't have the fog anymore


The turn signals and highbeams don't work at all either ...


I'm hoping someone can at least point me in the right kinda direction to figuring it out.. I'm getting a new underhood fuse block tomorrow so I won't have to bypass the relay, the last 6 things are new as of yesterday and I've been bypassing the relay for a long time so I don't think that's related ..


Not sure if this is relevent or not but it has just over 503,000k


I would really appreciate any ideas or suggestions 🦄🧚🏿‍♀️

 

To me, that sounds like a hot ground. As in, somewhere one of your grounds is getting battery voltage. Did you do anything prior to this happening? If you have an aftermarket stereo with amps, that is my first guess, (that or the BCM).

Some of the plastic connectors are known to melt, and the connections inside can make a circuit when they are not supposed to.

It sounds like everything you have said so far is on the interior fuse panel. On the end of the dash at the drivers side, (concealed when the door is closed), is a plastic cover that has another fuse panel. Then below the brake pedal / parking brake pedal is the MBEC. There is a connector panel underneath. Just to throw a guess, maybe some water, got in there, or maybe a connector got fried.... I'm really just throwing out whatever on what, but those are my guesses on where.

You can buy a factory service manual on ebay for about $10-$20. (service manual pdf 2006 yukon) should give you plenty of options that you can either get on disc, usb, or download. It would have every single wiring schematic, repair procedure, ground diagram, etc... The one I bought is 10K pages. Three thousand pages on the engines, 800 pages on the brakes. I'm just a learning DIYer and its helped me solve several electrical issues. What I would do is buy that service manual, and find the wiring circuits for what components are causing problems. You can check them with a test lead. If you wanted to check something right now. You should be able to pull that MBEC panel, and on the underside would be able to see any black wires that are ground, and test those. Perhaps you might find a connector that doesn't look right. If you have waited this long, I would get the pdf manual though.

If you wanted to try a dealer or mechanic, they can probably diagnose it by the module. The $5K+ scan tools can read specifically which electronic module is causing problems. I would expect an hour labor rate to diagnose (even if it takes em 3 minutes). If its less, THEN you get lucky.