gpraceworks

Original poster here. Back with a new update. Trans related repairs so far on my 2020 AT4 2500 Diesel. 1. 300 miles trans limits me to 40mph siad fluid was low. Fix: Top off fluid. 2. 1100 miles Same as #1 symptoms but limited to 20-30mph. Fix: Replaced trans valve body. 3. 2000 miles Same as 1&2 symptoms. Fix: Replaced entire transmission. Now for the most recent update. At just north of 8000 miles truck starts bucking back and forth like if someone grabbed you on your shoulders and shook you back and forth. No codes, no warning lights, no OnStar emails. Took it to the dealership on Monday. They can't figure out what is going on. I called and asked them to send me all the service records (9 pages). I used the term Lemon Law since I talked to a lawyer. Low and behold the service manager calls me with the service agent I've been working with and starts asking me how I've been using the truck. (Felt like they where trying to make a case). They even asked the make and model of my camper, how much is weighs. "Well let's see, I'm using it for its intended purpose. I tow a camper that weighs 11,300lbs a total of 4 times with the longest trip being 1.5 hours and the other 3 around 20 minutes locally". Now they are going to replace the transmission for a second time. I love the look of this truck, but I'm running out of trust and patience. The above only covers the transmission issue and not the recalls and other issues. It will be over 30 days if been without my truck by the time I get it back. They need to give me a new truck and junk this one!

I'm sure he Exaggerated a little bit...lol. I'm looking forward to getting this behind me and just enjoying it.

Diesel

I have a 2020 AT4 2500. At 375 miles, I pulled out onto a 3 lane road an went to give it the throttle and the truck jerked an bucked and wouldn't go. It limped home at about 35-40 mph because the transmission wouldn't shift. I got an email from OnStar to have it serviced immediately. I connected my Diagnostic tool and it gave me 4 errors, all transmission related. I took it to the dealer and they said the transmission fluid was low. They also fixed the Wireless charging pad, (factory didn't plug it in) I drove the truck for another 2 weeks and at around 1100 miles on the odometer the same thing happened. I haven't even towed anything yet! Took it in again. Dealership said GM is going to replace the transmission. Then called back and said they are not going to replace the transmission, but instead the "valve body". I asked for the part# of what they are replacing and he didn't know. I will get that information when I pick the truck up next week. This is super frustrating to say the least. I got a text from the salesperson where got the truck, and he said ther rep told him that 4 out of 5 trucks are having this or similar transmission problems. Has anyone else had this problem?

So I have a 2020 AT4 2500HD with the 10 speed. With 399 miles the transmission did a hard sputter and then i couldn't go over 40 mph. Had it towed and they said the trans fluid was low from the factory. i got it back and it was fine for 2 weeks, then the same thing happened again. First they said they need to replace the transmission, but I got a call today saying after doing some more back and forth with GM they need to replace the "Valve Body". I will try to get the part number from them. Interestingly both times this has happened was after i had driven the truck, parked it for a few hours then drove it again. In both cases the temperature dropped 10-20 degrees. I wounder if it is moisture/condensation from the warm case and cool outside temp? Need to check the fluid.