NHM25

Yep... that's what did it for me. I meant UBEC bolts... sorry for confusion... essentially the bolts that secure the fuse box to the body of the truck under the hood. If not tightened, it may not be properly grounded. This solution has worked for me and a few other folks, but not all. Worth a shot and probably something you can easily do -- at the very least show your dealer this bulletin.

Haven't had a single issue since tightening the UBC bolts. That did the trick. Runs like a champ now.

Check some of my previous posts. Try tightening the UBC bolts on your fuse box. This was the issue with my truck. Once tightened, i haven't had a single issue.

Good to hear. Hopefully this worked. I will say, I have not had a single issue with the truck since the dealer tightened the bolts. Went on a few big trips, camping, etc. It's running like a champ.

Add me to the list. This feature has maybe worked a handful of times since I bought the truck (2020 Sierra 1500 AT4 6.2L) a month ago. Have about 500 miles on it now. Live in Phoenix so the AC is always on but I'm worried. I'm one of the folks that had electrical issues days after buying truck (truck would not start) but dealer said they fixed by tightening bolts on fuse box. That issue has resolved but still spotty on the auto stop feature.

Great news! Hope this was the final fix.

How'd your road trip go? Hopefully no issues?

Totally agree with this.. Just reviewed pics of LOMAX vs BakFLIP and you're right... the LOMAX sits slightly higher than the BackFLIP (about half an inch). Both look really good, IMO. I'm with you, though... all about personal preference.

Man, you must be fun at parties.

Yah, man. Like I said, this comes down to a subjective decision regarding what works best for you and your needs. Agree the Lomax looks great, but looks weren't everything for me.

Okay, after spending more time being indecisive about this than any other topic in recent history, I've decided that I'm going with the BakFlip MX4. Here's why... what works for you will obviously be a bit different. RetraxPro XR was top of my list for a while. But, after seeing that the cover takes up about a foot of bed space, I was discouraged. My AT4 only has a 5'8" bed. I need all the space I can get. Also, if i need my full bed, it's not that easy to remove (in comparison to other models). Also, price is pretty high, though I know quality is great, you get a limited lifetime warranty, and it would be great to have those extra rails. However, I don't have any Kayaks , or anything else that would require me to stack cargo with a Thule rack that I couldn't put in my trailer... so, I moved on. Lomax Trifold. I'm not sure there's another cover that looks as good and is as low profile as this one. It's great looking. I love that you can remove the entire thing pretty easily if you need your whole bed. However, that also means that the cover can literally be easily stolen if fully open. Not much is keeping it secured to the rails. Also, I did not like that it doesn't lock after the first fold. Finally, it does not fold up vertically to allow 100% bed access. And, when folded all the way up, and strapped in, it takes up as much, if not more bed space than the Retrax. The only way you get to use your whole bed is if you take the whole thing out. Undercover Ultraflex. Also looks great and is VERY similar to the BakFlip. Love that it has a better warranty than the BakFlip (5 yrs), has a carpeted undercarriage, and comes with some freebies (cargo bag and LED lights). While not as easy to remove in comparison to the Lomax, it is still relatively easy to remove, should you need the whole bed space. However, you can also fold it up VERTICALLY to get near complete bed utilization. The one thing that turned me off was that it DOESN'T lean on your window and sits vertically. I've read reviews that when in the vertical position, it is still somewhat flimsy and your top brake light may be blocked entirely (as is the window). Why I'm going with the BakFlip... All the positives of the Undercover -- full bed usage, locking segments, can be removed rather easily. However, it leans against your window when fully open, allowing slight visibility out the window and full visibility of your top brake light/cargo light for following vehicles. Some downsides: I've read that Bakflip quality has waned in the last few years and the warranty is only 3 yrs. But, it's the best selling hard top trifold on the planet for a reason and the company has improved the model in the past few years (allowing for closure of the cover with and without tailgate open. Hope my train of thought helps folks decide. Do what will work best for you. I'll note that I too haven't purchased a cover. This is all based on my review of other reviews and what I think will work best for me.

Good news. Let us know how it goes. I haven't had a single issue since the dealer tightened the bolts on my fuse box. It's been the champ truck I had hoped for... Gaining confidence back a day at a time.

I hear you. Leaning more Lomax now... Figure these AT4s have such a small bed, may need every inch.

I'm all over the place with covers but think I've settled on either your Lomax or a RetraxPRO XR (retractable with rail compatibility). These are two are dramatically different covers. I like that the Lomax can be removed completely, but do not like that it does not have an individual lock. Love the Retrax ability to open and lock in any position, but hate that it takes up bed space and would be difficult to remove if needed. Any insights?

Looks great... what finish is that matte black or black urethane?

Odd question but here goes... I live in Phoenix. We haven't gotten rain in over 100 days. How necessary are those drain tubes? I just hate the thought of having to drill and/or obstructing part of the floor and losing more clean space.

They should bring back the slogan, "Like a Rock." Someone may have already posted this but (1) take videos of everything. This proved to the dealer that I actually had a problem because they could not replicate it and it ran perfectly when I took it in; (2) start the process of reaching out to GM -- I started with GM Customer Care ([email protected]) and they have now escalated the problem to a Customer Experience Manager, as I went full "Karen" on them and demanded that they provide a response not only for me, but the countless folks who are dealing with this issue (also send them links to these threads). The lack of acknowledgement is what infuriates me most.

Man, so sorry you have to go through this. I feel your pain, literally. The only thing that infuriates me more than a $60k + truck that does not start is a nonchalant dealer. This is going to turn into a Class Action against GM if the issue is not resolved soon. Thanks for the update, and please keep us posted. My confidence is still shaken to the core with this truck.

Man, really sorry. That's disappointing; GM really needs to get this thing straightened out. Completely unacceptable.

Interesting. I'll have to check mine. Seems like GM 's having issues tightening nuts on all critical electrical parts!

Awesome. Please keep us posted. Not sure I'll ever get the confidence back in my rig until I know this fix works for everyone who has experienced this nightmare.

Hey guys, reposting from another thread: 7/8/20: UPDATE: Dealer thinks they found the problem: Loose UBEC Bolts. There was a recent bulletin posted on 6/26/20 about this that may be the cause for this issue as a whole. Ask for document ID 5628169 or the following title for the GM bulletin: #PIT5756: Various Electrical Concerns (Inspect UBEC Bolts for Being Loose) - (June 26, 2020). SEE ATTACHED Condition: Some customers may comment on any number of electrical related symptoms. The following are some of the known reported ones: no crank no start starter grinds or re-engages after engine starts SES MIL IPC guages sweep/fluctute and/or various IPC warning lights or messages High or low system voltage May have any of the following DTC's: B1325, B2750, B305D, B297B, C0049, P0562, P0700, U0100, U0101, U0102, U3006 some of these concerns may be noticed with powertrain movement, like when accelerating or braking. Cause: These concerns could be caused by the X50A underhood fuse box bolts being loose. The X50A has built in indicators which pop up as the X50A bolts are tightened down, to inidcate the X50A is fully installed. In some cases, even if these green indicators are popped up, the bolts may still be loose. Correction: Inspect the X50A Underhood Fuse Block bolts and verify they are properly torqued to 53 lb in (6Nm) Dealer stated that my box was indeed loose (that's what she said). Has not been able to replicate issues. Really hoping this is the fix for my truck and all of yours. Will update forum either way. Best of luck. UPDATE: 7/14/20. I have had no issues with the truck so far. I start and drive it every day. I really hope this was the simple fix; hopefully you guys give it a try and it works. You can do this fix yourself. I've attached the bulletin for everyone here. Good luck. BUELLTIN (1).pdf

Yes, no issues whatsoever. While working from home, I start it and drive it daily. Slowly building back my confidence in the 65K rig. If you are 8 days out I would say try the fix yourself. It appears to be very easy. I've attached the bulletin here. Good luck and let us know if it works. BUELLTIN (1).pdf

UPDATE: Dealer thinks they found the problem: Loose UBEC Bolts. There was a recent bulletin posted on 6/26/20 about this that may be the cause for this issue as a whole. Ask for document ID 5628169 or the following title for the GM bulletin: #PIT5756: Various Electrical Concerns (Inspect UBEC Bolts for Being Loose) - (June 26, 2020). Condition: Some customers may comment on any number of electrical related symptoms. The following are some of the known reported ones: no crank no start starter grinds or re-engages after engine starts SES MIL IPC guages sweep/fluctute and/or various IPC warning lights or messages High or low system voltage May have any of the following DTC's: B1325, B2750, B305D, B297B, C0049, P0562, P0700, U0100, U0101, U0102, U3006 some of these concerns may be noticed with powertrain movement, like when accelerating or braking. Cause: These concerns could be caused by the X50A underhood fuse box bolts being loose. The X50A has built in indicators which pop up as the X50A bolts are tightened down, to inidcate the X50A is fully installed. In some cases, even if these green indicators are popped up, the bolts may still be loose. Correction: Inspect the X50A Underhood Fuse Block bolts and verify they are properly torqued to 53 lb in (6Nm) Dealer stated that my box was indeed loose (that's what she said). Has not been able to replicate issues. Really hoping this is the fix for my truck and all of yours. Will update forum either way. Best of luck.

I may have everyone beat on my timeline to frustration. Just purchased new 2020 GMC AT4 from Van GMC Buick in Scottsdale 3 DAYS AGO! The assembly date is June 20, 2020! It ran great the first two days... day 3, won't start. Total of 170 miles on the truck. Same issues that everyone has noted. Came outside, tried to open her up with the key fob and the battery was completely dead. Had to open manually. Push start did not function, no power whatsoever... basically a $65k brick in my driveway. Connected battery to wife's Explorer and got the dash to light up but it wouldn't start. Tons of error messages. Kept trying to start it and it finally lights up... but was running very rough with knocking. This morning, started it up and it ran great. Dropped it off at dealer and they tell me there are no codes, it's running fine, the alternator and the battery look good. So I send them the videos below and a link to this thread... No word yet but will keep you all posted. So incredibly frustrating. Love the truck but now have to worry about this... what happens if it doesn't start when my family and I are in the middle of the woods camping/hunting? Ridiculous. 2020 could not get any worse. Truck not starting when connected; charged for 20 min. https://www.youtube.com/watch?v=wEV5n6ZbkXU Truck won't start after charge: https://www.youtube.com/watch?v=_78kJthwf58 TRUCK FINALLY STARTS: https://www.youtube.com/watch?v=8xEFiD66ZIM Truck starts, idle is off: https://www.youtube.com/watch?v=xGd-6nNTU58&t=8s