07 Yukon Electrical Mayhem

[mentalattica]

Hello Everyone,

 

I just purchased a 2007 Yukon today, I test drove it and checked it out as best as I could before buying.

 

Fast forward 20 miles after purchase:

 

Taking a sharp highway ramp, "stabili-trak off" flashed followed by a few chimes. Then after parking, it would not restart, nor would the remote start work but the battery was fully charged. So on a whim I released the emergency brake and it started. So at this point I thought "maybe it won't start with the emergency brake down," which is a ludicrous idea. BUT the check engine light was on. So I grab my ODB reader and it threw codes U0073 and P0700 which I still haven't looked up yet. Then on the way home I hit a stretch of bumpy interstate and every single bump caused the "traction off," the speedometer was fluctuating 10-15 mph back and forth while maintaining the same speed, other gauges were jumping around like crazy also, followed by a bunch of chimes that literally scared the hell out of my family and I.

 

In my opinion, it's an electrical problem. Hitting those bumps at highway speeds and seeing the Yukon's reaction kind of confirms that to me. Anyone have any ideas? Is there any electrical problems that are known with these things? My family won't get back into it any more after this, and I have to drive it unfortunately. On a smooth or even city roads, it drives like a champ and doesn't have a trace of any problems, but now I'm really worried. It pisses me off after you just spent 24 grand and this happens on day one.

 

I purchased an extended warranty even though the Yukon has well under 50k mi, so I'm going to take it to the dealer after I receive my warranty policy, but I'm also a DIY kinda guy so is there anywhere in specific I should look to see if there are loose connections?

 

Thanks and sorry for the long winded post.

[txab]

U0073 Control Module Communication Bus Off

 

P0700 Transmission Control System (MIL Request)

[mentalattica]

I forgot to add that my power locks were locking and unlocking themselves also when hitting bumps.

 

Thanks for the reply Txab. Any idea what to look for or does it sound like the unit needs to be replaced?

[EZ_]

Wow, if its already having mechanical problems within 20 miles I'd take it back and make them fix it. When I bought my yukon I found that my rear passenger window wouldn't roll down a few days into the deal, they comped it and gave me a loaner while they waited for the part. They were embarrassed.

 

Did you buy from a private party or a dealership?

[EZ_]

Disconnect the battery for 20 min and see if that clears the check engine light. If you have an advance auto parts around they'll clear the check engine light for free, so you can see if its an error.

[Z71-K9]

Had the same exact problem with my 07 Vmax. Several threads on here discussing the matter. My fix was having the negative cable replaced. Under warranty.

[mentalattica]

Wow thanks for the quick responses!

 

Ez, yes it was a dealership. A pretty reputable one at that, I'm taking it back today but I have little faith in dealerships. Autozone actually did clear the codes for me. I could have done it myself, but I didn't want the to clear them and then it be such an intermittent issue that it doesn't happen again. The guy at Autozone recommended to clear it though to be sure that it does happen again.

 

Z71-K9 thanks for that info! That makes me feel a little bit better, I'll have to find those threads asap. If it's something that simple I would be relieved. I questioned why someone traded in such a nice SUV with such low mileage, and I'm wondering if this is why since it was out of bumper to bumper warranty so electrical is not covered.

[mentalattica]

So I took it in and surprisingly got first class service and a loaner car while they tried to figure it out

 

I talked to the used car manager, him and the service manager took the Yukon on a spin only for nothing to happen. But the service manager said it sounded like a loose ground somewhere. So I stressed they should ride on the same stretch of interstate and judging by the mileage when I picked it back up someone did take it back out for a 15 mile ride.

 

Anyways they found a "pinched" wire going to the fuse box in the dash. I have no idea what that means or why it would cause all of the mayhem but I was told they replaced the wire. I took it on about a 20 mile trip after picking it up and doubled back over that bumpy interstate stretch a few times and nothing happened.

 

I'm still a little uneasy after it freaking my family out so bad. But all seems well so far.

 

BTW, Ez where'd you get those headlights? They look awesome.

[98 Z71 SLT]

They fixed it right. these trucks had a problem with a wiring harness getting pinched at the e-brake pedal mechanism.