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I waited several extra months for the AT4's release to purchase my truck. Less than 1 day of light driving and 70 miles into my new truck the transmission started to slip in and out of gear. I pulled into a parking lot and when I shifted into revers the truck slowly rolled forward. Onstar had a flat bed tow truck there within an hour to bring the day old truck back to the dealer. The dealer can not start work on the truck until GM approves the new transmission. I am told that there is a lot of extra paperwork and approval because there are so few miles and it is a new truck. I would think that GM would want to maintain their customer loyalty and support their new designs before aggravating buyers of new trucks. I have been a lifelong GM buyer, but thinking that i should have gone with a Ford or Ram. Has anyone else had to wait for repairs on a brand new vehicle?

John Goreham Contributing Writer, GM-Trucks.com 4-25-2019 Back in December, GM-Trucks.com member Jammin87SS posted a note here about a class-action suit related to GM 8-speed automatic transmissions. This transmission was used widely by GM, including in the Sierra, Silverado, Colorado, and Canyon pickup trucks. Owners have been complaining of shuddering and hesitation. Owner of a Silverado, Ed T., wrote a typical description for CarComplaints. He says, "Ever since I bought this truck new there has always been a shifting problem. This problem occurs whenever I slow down to a fairly low speed and then accelerate. When I accelerate there is a hesitation for a second or 2. This is very annoying and could potentially be dangerous. I have contacted my dealer and he just says "that's the way they shift, no fix"??? Dealer also stated that the transmissions have a learning chip and shifts the way a person normally drives - that's total BS. I have had my truck for over 2 years and it still shifts poorly. Besides the above I love my truck very much, GM just has to fix this problem..." GM knows there is a problem. It has issued both notices to its dealer's technicians and also TSBs. However, it has yet to find a solution that works. There is a class action suit that you can learn more about here. Our questions for our members are; 1) Have you experienced any issues with your 8-speed, and 2) was the dealer able to fix it? Let us know in the comments below.

Anyone have a check engine light show up then go away and come back? Code uo129 lost communication with brake control module, UO101 lost communication with transmission Control Module. Went to bed with no check engine light, woke up in the morning for work and noticed the truck would not remote start. When I go in to head to work noticed check engine light. After work ran codes. Shortly after getting codes and using google to research check engine light was gone. Went for a drive never came back on. Woke up this morning it was on again. Can anybody relate?

Hello, Has anyone else experienced any shifting issues on their 2019's? The big one I seem to get a hard shift point around 2-4k RPM coming off a stop under light gradual acceleration shifting from 1st to 2nd gear. It's fairly random but seems to be more common after the transmission heats up 150-160 degrees or more, though it'll happen cooler too. The other is when feathering the throttle in traffic the downshifting seems a little harder than it should be, not as hard as the upshift and it doesn't clunk like my old 16' but it's a feeling like driving over a small bump occasionally but it's happened enough while watching the RPM needle shift to think it's not just the coincidence of running over a little bump. Typically during low traffic speeds < 30mph. All in all, the transmission is a vast improvement and is way smother compared to my clunky 2016 5.3L 6 speed Z71 which I traded in with 35k miles after valve sticking issues and a transmission rebuild replaced a fair bit of the transmission (torque converter, valve body, transmission pump). I cant tell if i'm just sensitive to the transmission or if I have something worth pursuing, service department says to give it 1500/2000 miles while the truck is "learning" as mentioned in other threads, I currently have just shy of 1100. After that I dread the "normal behavior" discussion. Overall it's a great truck, really smooth overall and a beast on the open road, in fact it's so smooth most of the time I think it might make the slow speed hiccups seem worse than they are. It's just a concern knowing that if it starts shifting issues at 500 miles, what's it gonna be doing at 20k miles etc.. Thanks everyone for reading! What's your experience? 2019 Silverado 5.3 V8, 4x4, Z71, RST

Question to all new truck buyers who bought a 2018 Chevy Colorado, you having any transmission issues, like slipping between 2nd and 3rd gear on the automatic floor shiftier or problems with the + and - buttons ?

So driving the family to supper today in my 16 crew cab 5.3 nice hot 21*C day had the AC on and after driving thru some stop and go traffic for 20 min and getting to the restaurant I backed into a slightly up hill stall and pull forward to straighten out and back in again and we feel a slight shudder vibration. I checked the trans temp it was 88C and sat in park with the slight shudder and checked my transmission fluid it was slightly below the hot section but i was slightly rear end high. Came out to leave hour and a half later and could just barely still feel a slight shudder and it didn't get change with a rev of the engine. I drove it the 12km home and it felt normal no shudder at stop lights after we left. Im up to 106,000km and plan to get the transmission fluid changed and filter as I bought it with 72,000kms last april and am unsure now if the dealer did the transmission filter and fluid. Any ideas?

So my new to me 2014 Silverado with 95,000 miles just lost its transmission in the first week of me owning it. In calling around to local transmission shops the general consensus is that these transmissions will only reasonably last 80 to 100 thousand miles without either the pump or torque converter going out. Anybody have any thoughts or similar findings?

I have an appointment to take my truck in for some transmission work next week for a vibration that started yesterday. At first it kinda felt like a loose wheel or a tire was going out of balance but throughout the day it got worse. If I'm in 8th gear cruising at any speed about every 20 seconds the whole truck shakes for a couple seconds and at every up shift it shakes when it grabs the next gear. If I run in manual in 7th gear I don't get any shaking at highway speeds just in 8th. Kinda feels like it maybe the torque converter? Anyone else experience anything like this. Truck just turned over 16k miles. Just curious what to expect for repairs if anyone else has had this problem.

Just wanted to post on here, as I have seen no less than a thousand posts with questions about the 6L80E, specifically about the power threshold of a stock unit. I have a 2014 GMC Sierra SLT Crew Cab Standard Bed stock 3.42 gears stock drive shaft stock 20" rims/tires 6.2L fully forged top/bottom end "Armageddon Twin Nagasaki's" (GT3582R's) e-boost 2 gauge Z06/LT4 fuel system 365lph in-tank Armageddon fuel pump QTP exhaust cut-outs and laid down 965rwhp/850 rwtq on a mustang dyno with 18psi on 116 race fuel (cut-outs open). I say all of this because the stock transmission detonated the 4-5-6 shaft (intermediate hub) near the splines. I took it to a "race shop" that said they would upgrade as much as they could; and was told at the time, there were limited aftermarket parts available for the 6L80E. This was mid 2018 with less than 10K miles on the truck and about 500 miles on the engine/turbo build and I discovered that was not entirely true. I drove the truck after their work, with "spirited road driving" while the roads were wet no less. Long story short; they f'd me and I detonated the 4-5-6 stock intermediate shaft again within 100 miles and no traction at all. They apparently replaced all parts that were broken with stock parts! Moving on, I took my truck to a different shop and researched my a** off and found PATC Transmissions. I had a warm and fuzzy after speaking with them and ordered the Phoenix Level 4 Master Rebuild kit among a few other minor accoutrements and re-tuning of my TCM by Mike from Century Automotive. It is now APR 2019 and I am about 1 1/2 weeks away from having the my billet planetary gear mailed to me; for the new, more reputable shop in my area to install all of this PATC bada**ery. If anyone is truly interested, I will post new info once I put the new Phoenix Master Rebuild kit through the ringer with the full weight/horsepower/torque of my particular application...I hope this helps if there are some lost souls out there that may be headed down the same long. hard. road. of a "full send" like myself! Please post if you have questions/comments/concerns; as I have "been there done that and forgot the t-shirt" with the L86/6L80E so far.

I have a 2007 Tahoe 2wd, 5.3L. The transmission gets hot, 190-200 degrees F, only when in overdrive. If I shift down to 3rd, the temp will start to decrease. Has anybody had this problem before or know of any solutions? Thanks.

Hello all, so this weekend i took my 2000 Silverado out camping and on my 3rd day out i went to start the truck and warm it up and drove it around the campsite and everything worked fine, parked the truck and then grabbed the family and loaded up, went to shift from park to drive and the lever just fell loose, wont go into any gear from the shifter but if i get under the truck i can shift into all gears fine, then once in drive i can shift from drive to neutral reverse and park just fine but wont go to any gear from park, cable was replaced last year. No clue where to start but everything under the truck is connected and in working order. 2000 extended cab short bed 5.3l 4l60e. 2wd

Hey Guys, I have this transmission that I found in my backyard of my landlords house and was wondering if you guys could tell me anything about it! Thanks. It also says M97 on the side and GM 14 stamped!

Hey all, 2017 Silverado, 5.3/6spd. My transmission issue only happens when I first drive the truck for the first time in the morning. The truck has to have been sitting overnight for this to occur. After starting the truck and driving, the trans will "fish bite" or stutter when shifting from third to fourth. It will do this once, (maybe twice) and be good and problem free for the rest of the day. Has anyone else experienced this? It only happens when the truck is first driven after sitting overnight. It's not really a major issue, as it doesn't happen again after the first time, but it's pretty annoying. This issue only occurs at light/part throttle, and my speed is around 25-30 mph. I do not notice any variances on the tach while this happens. Also, if I drive with more pedal/throttle, I will not experience this stutter. I spoke with the dealer about this when I went in for my second free oil change, and they could not replicate the issue. During my first trip to the dealer, they downloaded a program update for the transmission. It helped overall, but the isolated problem is still present in the morning. I have read somewhere on this forum, that this was a "normal" occurance, and attempts to remedy should not be attempted. I believe that post mentioned that transmission fluid temperature played some part in this. Any ideas or input? Thanks in advance! Steve

Hello, I have a 2018 Silverado, around 11000 miles on it. Driving the other day, lost power around 35 mph, pulled into a parking lot, re started the truck and checked to make sure I was in 2wd etc. Began driving again, toward home due to something being wrong and same issue occurred including check engine light. Had vehicle towed Friday night when it happened, at dealer now which isn't open until tomorrow. Has anyone experienced anything similar?

I have a 2015 Yukon Denali, it is lifted with 35’s, the lift has about 1500 miles on it now, I have had no issues up until recent. The issue is I’m getting a pretty loud metal on metal clacking or tapping noise from some where in the front diff or transmission. It is most predominate from speeds 30mph down to about 10mph. The noise will start when I let off the gas while driving to coast or slow down, it will do it intermittently at higher speeds but not near as much but it is the same issue for sure. It seems like it starts after I let off the gas and the rpms drop down to around 1200 or less in a coast. The noise will start off not as loud and progressively get louder if I coast without touching the gas. As soon as i touch the gas the noise will go away, it does not do this in manual mode only in automatic. I have had the lift looked over multiple times and now I don’t think it has anything to do with it other than the additional Strain may have caused and already underlying problem to become more profound. Any help on this matter would be greatly appreciated!

Who else is having a transmission issue? I saw the thread about hard shift into 2nd, but towing yesterday at 65 mph the transmission literally jolted the truck like it fell out on the freeway, scared the sh*t out of me. Also under acceleration it feels at times like it cant find the right gear, hesitates a bit then finds it. Also when decelerating, letting off the gas it paused then hits. Wanted to see if anyone else is having similar issues. Ive taken it twice to my local dealership and both times they say "Sorry, we couldnt get it to replicate for us, here are your keys."

My 2018 denali changes one of the digital gauges to tranny temp when I press tow-haul. Does the 2019 AT4 with tech pkg do the same, or do you have to go in the trailering app, etc.?

I did a quick search and couldn't find anyone with my problem. The 8 speed trans in my 2017 Denali is increasingly shifting hard into first gear. Occasionally it will shift hard while slowly coming to a stop at a signal during normal around town driving. The other day I made a left turn slowly onto a street with an incline. When I applied a light amount of power, it shifted so hard into first that my head hit the head rest. When mentioning hard shifting to the dealer, they say that it is the nature of the beast. I sold my 2011 Denali to my son. I am really missing the 6 speed trans. Has anyone else had this problem and found a fix? Thanks everyone Jerry

Hello all! First post here! What brought me here was the 8l90 torque converter lockup shudder issue. Most times I'd just take this truck to the dealer and let them sort it out, but as it's out of warranty, this is not something I'd like to pay >$600 to repair (this price was quoted to me for the flush and filter change). After talking to a few service advisors I've found that each of them planned on using a different solution to attempt to alleviate the shudder. The first was going to proceed via one of the bulletins and do a triple fluid swap and filter change, the others were just going to do a standard flush and fluid swap. I plan on owning this vehicle for another few months until the 19's become a little more negotiable but cannot stand to let this shudder go on that long and am a bit worried about destroying the torque converter in the process and washing a whole bunch of parts down into the transmission. So.... my question is if anyone has performed this fluid swap themselves, if it alleviated the issue, and if the filter change is necessary? I saw that many of the Corvette guys were swapping to the Mobil 1 fluid with some success, however, I didn't think this was as much of a fluid performance issue as it was a suspended clutch material / dirty fluid issue. Any help would be greatly appreciated!!!!!!

Hello, This is a 1999 Chevy Silverado 5.3l, 4wd push button style, 4L60E transmission, 153k. I have a green fluid leak (T-case fluid) coming from the front axel input shaft seal, drivers side. It obviously gets thrown around all over surrounding components when driven in current condition. The leak will accumulate about 2 or 3 drips on the ground overnight. It's been going on for a good while judging by the amount of fluid caked on everything. I've only driven approximately 50 miles since i noticed issue, all in 2wd. My questions are whether or not i risk significant damage to the case if ONLY driven in 2wd while also adding fluid as needed? Also, is there an "inner" seal in the transfer case that will be exposed when drive shaft is removed from t-case? If so, what is the responsibility of "inner" seal and is there a reason it should also be replaced simultaneously? When i'm in that deep i'd rather do whatever is necessary and logical. Thanks for any help with stated questions and I also love to hear any related advice or experience! Taking it to a shop is not an option as I have little money and major trust issues. Trust issues stemming from several bad experiences in the past and most recently, pertaining to this vehicle. I bought this truck for $6,500, everything is in VERY good shape, recently had a 90k motor installed @ 150k (i purchased it at 152.5k) as a private party transaction from the auto shop owner who installed the second motor. Turns out recently installed engine either has a cracked head or head gasket as the black light test reveals coolant coming from exhaust among other confirmations... AAAGGGHH. That's a completely different story that's being dealt with but figured i'd share my reasons for NOT TAKING IT TO ANYONE mentality. Auto salesmen/mechanics can be total sleezeballs. From now on it's my way or the highway, to my own dismay haha.

Long time reader and first time poster. I recently started to have vibration issues with my 2015 Yukon Denali. It started after the last scheduled oil change and tire rotation. I noticed the vehicle vibrating quite often. I started paying more attention to it and realized there was a shudder in-between gears that became worse as the transmission warmed up. Took it to the dealer I purchased it at and it was a bit of a fiasco because they were backlogged and ended up taking it to another dealer who performed 2810175 (updated TCM with latest calibration and relearn). They handed me the vehicle and said all fixed. Took the vehicle home and it seemed to be ok but started noticing the shudder again. One question is after this, is it expected that there should be a relearn time for X miles while its relearning the shift adapts/pressures? Is there an estimated number of miles for this? It seems to shudder less often but when it does it seems worse than before. I've only driven it about 60 miles since the recalibration. I'm fully aware of PIP5337 and asked them about this but they said the TCC was not bad. The vehicle was purchased June of 2015 so its definitely manufactured before November of 2015 which PIP5337D mentions. As I drive it more and more, I feel less of a transmission shudder but more road vibration than I felt in the loaner 2016 Yukon SLT or my wife's Kia Soul. I'm wondering if its possible they rebalanced improperly. The road vibration seems to be at lower speeds. At higher speeds it is better but may just be the quality of the roads I am driving on at lower speeds. I do notice the TAC jumps about 100 rpm during most shifts and not sure if this is normal. It seems to do this when the TCC speed should be 0 (around 2000PM) shifts. I realize it would not be fully locked under 1600RPM. At this point, I am not really sure if I am just paying too much attention to every bump on the road or if there is an actual issue. Are there any objective ways to determine if there is an actual issue and express that in a way that will not completely annoy the dealer? I have already had to pull this vehicle from one dealer because they were so backlogged it would have been in the lot sitting for repair for 23 days. With that said, they planned on doing a tear down on it to inspect and thought it was the TCC. Any help or guidance is much appreciated. Thanks!

I'm posting the factory service manuals for GMC/GM 2007-2009 trucks as there are a ton of questions around specs and trouble shooting. This manual covers everything you need to trouble shoot and all the specs you need to rebuild/repair your truck.

So when the truck was newer I used 4x4 a few times and it would make almost a metallic grinding noise when turning. I took it into the dealership multiple times trying to get a fix and they kept saying there was no fix. So be it. It works still even with the noise. This truck was always maintained by the dealership until 80k miles. At 72kmiles the check engine light came on almost out of no where and I took it to the dealership to find out the injectors were bad! What the heck! Then andother 8k later the rear differential started leaking oil and I had to replace that. That was fun 4K into a 2015 truck in the same year in repairs that shouldn’t have happened that early in the trucks life. Thennnnnnnnn at 104k the transmission went out!!!! What in the heck! All of these repairs were done in a 9 month period. 10k into a 4 year old truck. I’m very disappointed in this truck. I always kept up on oil changes and most maintenance. I did not flush the transmission at 60 but that still should not have put my transmission out at 100k. I have towed about 4K max behind this truck less then 8 times for no more then a total of 200 miles so I’m not rough on the transmission. I’ve also only had it off-road 1x early on in its life so definitely not had a rough life. Almost 60% of the miles are freeway miles. These problems should not be happening to a Chevy truck. I’m really disappointed. All my ford friends have given me so much Crapp and honestly, I may as well have bought a cheaper not as well designed truck and saved myself about 10-15% on the ford truck. Not sure if there’s any possibility of gettting any of that 10k covered from Chevy but that would really make me think a lot higher of the brand.

Hey guys, I want to work on my truck and upgrade it but i dont know what i should do. What are some things you have done to your engine and drive train to enhance performance and add durability? *I drive a 2014 LTZ 5.3

Just curious if anyone has the same issue I've been having. So on the very first shift of the day from 3-4 my trans seems to slip into gear. After the initial run through the gears it shifts great every single time after that. I have real basic stuff done to my 14 Sierra..cold air intake, cat back exhaust and blackbear tune (yes the trans was tuned). It really seems to be temperature related because it gradually got worse the colder the nights get (I live in the northeast). And no matter how long I let the truck warm up before I drive it, it does the slip but only 1 time. Not sure if this is also related but the tuner said the torque converter locks after the shift into 4th gear.