We have classified the 2 complaints from 2005 GMC Yukon XL 1500 about POWER TRAIN into the following categories.
My 2005 yukon xl will, at random, shift itself into 4 wheel lo. it happens while driving and at speeds of 30+ mph. all of the lights on the push-button 4wd control module will light up or flash. no amount of button-pushing will disengage 4 wheel drive. i the car will slam to a 5 mph crawl when it does this. also the traction control system deactivates at the same time. has happened over 40 times now.
This basic incident has occurred approximately ten times. the 4wd control module malfunctions at random. the vehicle message center will display "service 4wd," and a clicking sound can be heard as the lights on the transfer case control panel switch on and off, switching the vehicle in and out of gear. several times this has happened in such a way that the truck shifted into 4lo at moderate speed. once, the vehicle stalled in an intersection with the abrupt shift. i am convinced that this is a systematic issue with gm 4wd trucks, but it is in no way being addressed. it is an extreme safety hazard when a 5400 lb. vehicle suddenly shifts into low range or neutral without advance warning. a simple internet search shows that this has happened to many other gm vehicle owners. the only remedy seems to be removing the relay to cut power to the module, thus rendering this "mighty" 4x4 a 2wd sled. this is a safety hazard of the highest order! i cannot say enough negative things about the electrical system of this vehicle in particular and the build quality in general. it destroys tires, it is a pleasant surprise when something works as it should, and i had to replace the "heavy duty" transmission at 120k when the power bands catastrophically failed. for shame, general motors! i will never again purchase another of your shoddy vehicles. *tr
While returning home from a camping trip, sudden loss of 3rd and 4th gears in transmission. we were traveling on the freeway, towing a trailer when this occurred. (the vehicle is equipped with factory tow package.) in researching this problem, i was surprised that gm has opened a couple of tsb's relating to it. *tr
Automatic transmission mode (4x4, 4x2, awd) shifting problems and changing from selection by itself; recurring in nature; vehicle dragging; abrupt jerking - multiple incidents and multiple repairs; only constant is that the problem always comes back and continues to this day; only service provider to have worked on this issue is swope gmc in louisville, ky. .