swillson1980

OP My 2012 sierra had this very problem 2 months ago and evolved into completely coming out of gear and revving up like its in neutral while in overdrive trying to accelerate from a stop light. currently at transmission shop for new torque converter/rebuild. Also developed a small oil leak so they are replacing the rear main seal as well.

Funny you mention that about transmission shops because a story like that has motivated me through the years to research and try to do the work myself, if possible... Wish they had that place down here in south Louisiana...I'd be in there tomorrow...

Thanks everyone for the replies. I've had a feeling the torque convertor could be the problem as well. I couldn't go any longer without a truck so I dropped it off at a local transmission shop and they are looking at it today. Last week when I gave him the same description I put in here, he mentioned torque convertor. He also mentioned $3200 for a rebuild, if that's what it takes. Dealer where I bought the truck mentioned $4800 for a rebuild, and $5500 from a remanufactured transmission from the manufacturer but had a 3-4 month lead time to get here. The truck has 146k miles and I have never changed the fluid. Probably a big mistake? I guess I've heard conflicting opinions on whether to change or not. My last gmc (a 2002 model) went to 175k miles before it threw a rod and busted a hole in the oil pan at 10 years old; which afterwards I bought current truck. Never changed the trans fluid on that truck. Is the TECHM a solenoid as in the P2823 code? Thanks again for the info...

Hello everyone, new member here...truck prices are outrageous and I'm hoping I can salvage my 2012 sierra for a few more years... Wrote a short story on what's led up to now...Hopefully there are some ideas for a fix that doesn't involve a new transmission (finger's crossed)...thanks in advance for any advice... About 4 months ago my traction control/stabilitrak light came on. I ignored it and it eventually went off thinking I could do without it for a while. A couple months ago the truck started consistently jumping about 200 rpms every 5 seconds or so at 70 mph. That evolved to doing it at 30 mph as well a week later. I hooked up to my neighbor's computer and said change rear speed sensor. I've done this before so I ordered part and installed on rear left wheel. RPM jumping persisted at every gear, but mostly up to 3rd gear then it got less on higher gears, traction control problem fixed, but still no check engine symbol showing on the dash. Sunday I cranked it up and heard a whine, almost like a pump trying to work around the transmission/oil pan area, then sound went away after a second or two. Started driving and it would 'whine' every gear change for a short spurt. Yesterday it started coming out of gear while driving, with a pretty good 'bucking action' associated with it...YIKES! Yesterday afternoon, while idling at a light trying to make it home, it would not go into gear at all. Turned it off, turned it on, put in drive and it would go for a bit then get out of gear. Did this multiple times before figuring out I could go less than 20 mph and not allowing it to get above 2nd gear (I think). The check engine symbol never came on through this whole ordeal (nearly 2 months) until yesterday when it wouldn't go in gear. I'm kicking myself for not bringing it in to a shop sooner but I was trying to figure out a fix from internet experience and videos...to no avail... So I checked codes with my neighbor's computer reader when I got home and got the following: P0700 Transmission Control System P0796 Pressure Control Solenoid C Performance/Stuck Off P2723 Pressure Control Solenoid E Performance/Stuck Off P2771 Four Wheel Drive (4WD) Low Switch Circuit Trans dip stick doesn't indicate any fluid loss. Any ideas? I've read the 2014-2019 possibly had similar trans issues. Bad TCM? Solenoids? Rebuild? New Trans? I'd hoping some on hear may have some experience with this before I limp it over to a shop for any work. Full disclosure, I'm not a mechanic by any means, just swap out some parts here and there such as rear wheel speed sensers, brake pads, power steering pump, oil pressure senser to date...I used to change my own oil but have had the dealer do it for this truck...truck does have a small oil leak but i'm guessing it's unrelated...