kpanza

Same issue here, happens way too often with XM. But I also have the issue where about once a week (and seems to be getting worse, didn't do this at all the first 4-5 months) I have NO SOUND at all, from ANY source (AM/FM/Sirius/USB Pandora, etc)...yesterday, it took 3 restarts until the sound would come back??

TSB # 19-NA-129

I agree, sucks on a new truck, but just give them the TSB # and tell them to do it...it solved 90% of my noise. Call your service advisor or manager (sadly, I'm on first name basis with my Service MANAGER), tell them you want them to do a quick test drive with you (they have to confirm it is clunking), then tell them to order the parts required under the TSB. Once they get the parts in, have them call you, and you can be in and out in less than an hour. That's how I did it. I didn't even have to do the test drive part, but that is because I've had other big issues with truck and he wants to try to keep me happy...

Air bags, or swap to aftermarket steel springs (Deaver, Alcan, etc). I'd just do the Air Lift bags.

You need to get Gm Customer Service involved...the kit clearly states that the reflash is included with the kit from GM. Get your money back!

My lifetime just went up to 13.1mpg (3300 miles) after a 700 mile roadtrip to Mammoth last weekend. Got about 17mpg on way up (cruising at 75, but continuous climb from sea level to 9000ft), and almost 22mpg on way home (75-80, almost all downhill, but got caught in traffic on Cajon Pass). It's just the around town that kills it...I average 12-13, and with my 4 year old in the truck, driving gingerly and no excessive throttle...it just is what it is. Disappointed it's not better than my 2010 with 6.2/6spd combo (which also had 3.73 gears with Max Tow!), but it's just an overall bigger and heavier beast.

If you have a 2020 SLT, you don't have the Tech pkg, so you won't have any other HUD info showing up on windshield. Just that red brake warning. Tech pkg was NOT available on 2020 SLTs, so no HUD. Not sure about Spotify, I don't use it...

And I'm sure you have thought of it, since you are actually asking the right questions and want to do the right thing - but the important thing is to STAY BELOW the maximums (TW, GVCR, payloads, etc) for LEGAL reasons. Yes, our trucks can (and many do) physically tow more than the printed numbers on our doorjambs, but should you get in an accident (your fault or not), and you were found to be over the specified limits for your truck, an attorney will sue you for everything you have! I always get the Max Tow pkg to give me more safety (and legal) margin, use a good WD hitch and weigh the setup. Most of us who tow often would be better off with a 2500, but we don't want to daily-drive one of them...so a little more homework on weights has to be done to keep everyone safe. Based on the weights, I'd vote for the GD trailer as well, considering we all load MORE than we think we will! Happy trailering!

Sept 14th for Crew and Double cabs is what I read. We will see, waiting on one myself for a GM replacement...haven't heard anything since late July when order was placed.

Yes, do the TSB - 19-NA-129. It gets rid of 90% of the noise.

I am 6 months in on my 2020 SLT, and currently waiting for my '21 SLT...my truck was in shop for over 60 days in the first 3 months, GM offered right away to do a buyback or replacement. Because my situation was kind of unique due to Covid shutting everything down (had bad tranny leak that they couldn't get parts for after the 1st botched attempt), I am giving GMC another go on a '21 replacement truck. All I am waiting for is the new lease payment info (the process is totally backwards, they can't give you a price until their is a VIN#!) If the payment stays same or close to it, I will go ahead with the new '21 (has additional options like Tech pkg, tow mirrors, and a few deletions of stuff I don't use on my current truck - sunroof, etc). If the payment is not close to what I have now, I will just keep what I have. I also of course have the option of a straight Buyback. So yes, if your truck qualifies for your state's Lemon laws, GM can and will get you out of a lease.

Of course it's going to get warmer in the sand! But 220 is fine...you start getting over 240-250, the fluid starts breaking down faster and you should change the fluid more often than the factory calls for. Sand has huge amount of resistance, gonna build heat in the tranny very quick. Are you shifting "manually", as in, using the shift buttons to hold gears? That should help a bit, but the torque converter is gonna build up lots of heat in that environment. Frankly, I'm impressed it only went to 220 with what you describe.

Yeah, you need to use real c-clamps as lapoolboy said. Get them tight as close as you can to the pin.

If you look closer, it appears that the entire door is just a smidge low at the rear...dealer should be able to shim it, or maybe adjust striker a hair up?

Love mine, tows easy, rides pretty well unloaded considering. Doesn't seem like the difference between stock 3.23 gears and the NHT 3.42s is that great, but my fuel mileage is nowhere near what a lot of guys claim their 6.2s get...over my first 2300 miles, averaging 12.2mpg. Lots of city stop and go, but I drive it like an old man trying to get better mpgs...my 2010 NHT w 6.2L and 3.73s (with only a 6 speed!) got much better mileage over its lifetime. But all in all it's nice to have that safety margin when towing...my '73 K5 rock crawler on an 18' car hauler is over 9,000lbs, and having the 1,700lbs of cargo capacity is necessary then... I am in that "probably should have a 2500 truck" category, but I like the ride of the 1500s for my daily driver, so going with NHT gets me in that sweet spot.

I am going to be getting one very soon, Banks makes GREAT stuff. You can tell they engineered this thing right, is well thought out. I will not be getting the gauge or pod...I mean, after the first day or two of playing with it, you won't touch it again! But, I know a lot of guys like all of the gadgets and sticking stuff all over the truck, so to each their own. I like keeping the interior clean and uncluttered, will just use the phone app to set it up and forget it. Was happily surprised that the price was in-line with the competition, and it seems is a higher quality design.

Well, I am happy to report that the TSB made 90% of the clunking/bowling ball noise go away over bumps, backing out of driveway, etc! I say "90%", because if I turn off the radio AND A/C, and hit the same spots that made it clunk like crazy before, I can just BARELY make out the noise. So, count me in the lucky ones that this fix seems to work for. Now the real test will be does it LAST going forward? Or will it come back...stay tuned, will update my findings as time goes on.

My truck is in the stealership getting the TSB done right now, for the rear suspension clunking (bowling ball effect)...will post up if it works when I get the truck back. Been a GM guy all my life, but am starting to lose the faith - they gave me an Escalade ESV for a loaner, and after I get the baby seats loaded in, all my stuff, I fire it up to leave...dashboard lights up with all kinds of error messages about steering assist, stabilitrak, you name it...so they go scan it, clear it, have no clue why it's happening. Since I only work about 4 miles from the dealer, they say "just take it, we are sure it's just some computer glitch"... ha! Sure enough, a mile down the street, error messages galore. Unreal.

Great writeup! Felt like I was a passenger...and great to hear that the Dmax Jr did so well. My guess on the cruise control issue was some splattered bugs obscuring the sensor? The only time it happened on my truck it was that...

Yes...the 6.2L has no equal among the other trucks, is the quietest, smoothest, fastest truck I've had (and have had several, including F150/250s). Couple random electronic issues, but they all have those now...loving my '20 SLT Max Tow. I did have an extended stay at the dealer due to a trans leak, but if it weren't for Covid, it would have been simple and quick fix...so I can't hold the extended stay against GM really (was back in March when everything was shut down). Should a brand new truck have a leaking trans pump? Nope. But been smooth sailing since and really enjoy driving it and towing with it. I had issues with my F150 with the Ecoboost, and we have a Chrysler Pacifica with the Uconnect, and it has WAY more electronic issues! We are driving big computers now, bound to be issues with electronics!

Bonefisher, Cool! I will let you know if I hear anything, you do the same. Our trucks are very similar! Most important to me was the Tech pkg with the cameras for towing, plus the mirrors. Why they didn't allow those features on a MAX TOW truck last year makes zero sense, so hopefully they allow it this year. I never use the sunroof, so I opted for the Performance pkg instead. Hopefully these trucks get delivered before OCTOBER, which I heard was the estimate...guess we will see.

Jeezus, go make another thread about Double Cabs already! Last Friday I went in to order the new '21 (GM is replacing my '20 due to Lemon Law), and so far I haven't heard anything back. My '20 was an SLT w Max Tow and 6.2L, but of course for '20 you couldn't get the Trailer mIrrors or the Tech Pkg on the SLT (made no sense GM!) But, according to the order guide, you can for '21. So I have a '21 SLT 4x4 CC with 6.2L, Max Tow, every major option except sunroof, plus the Tech Pkg and Trailer Mirrors! I am HOPING that GM doesn't send a rejection notice to the dealer, fingers are crossed it can be built like this! Will keep you posted...

If you have seen other posts and threads, this TSB has NOT solved the issue for many owners...

Yeah, this is a weird one. Seems like it affects trucks across the trim levels, max tow and non-max tow, etc. My '20 SLT 4x4 w Max Tow has done it since day 1, but it actually sounds like it is getting louder and happening more often, am now at 1900 miles.

So, all of my leaf spring bolts were to spec, both at shackle end and fixed end. But one thing that I did notice, was the passenger side front mount...the bushing is torn and looks too compressed on the outside edge. The inboard shoulder of the bushing is about 1/4" thick and ok...but the outboard shoulder is less than 1/8" thick and has a tear? It's weird, the inboard part of the leaf spring mount extends to just past the bushing edge...but the outboard part of the mount, it's too short for the bushing. The lower edge of the bushing is not supported by the metal mount...seems to be a design flaw. I will have to wait til I can get someone to help me rock the truck while I lay under there watching that bushing...really hoping that the leaf spring eye is not making metal on metal contact with the mount!!