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Discussion Starter #1
My 2014 LTZ seems to be slipping occasionally and shifting hard. Is there any things i should have looked at to see what the issue could be? Have about 120k on it.


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You have a 6T-- automatic correct? And does it shift late, such as doing 45 mph and shifting from 2 to 1.5 then to 1k rpm rather than jump to gear, like 1 to 4 or 5?
 

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Discussion Starter #3
It shifts hard or feels like it’s slipping sometimes. Like it revs the shifts. Like going from 1st to 2 bd under medium acceleration


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May be too late and damage already done, but has the trans fluid been changed as per the maintenance schedule?
 

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I see, I only ask the specific because the 6 speed has a common TCM problem where the fluid pressure switches break and then your shifts aren't very smooth. It seems like you have slip the way you explain, I remember reading that the 4 and 6 both have problems with the solenoid actuator, that was common as well. Go get your OBDII scanned; scan the transmission exactly and see if you have a P0989 Fluid Pressure Sensor/Switch Circuit Low code, you can do that for free at Autozone or where ever you please. If you have that code on this 6 speed then I must persist you have a blown TCM fluid pressure switch. If you see metallic flakes on your trans dipstick, I can't help you from there it's either both the TCM and worn wave plates or some other problem.

New TCM is relatively $500 for the part but the actual repair of the switches is a 15 dollar kit and you can basically do it yourself. Also check your transmission fluid via dipstick when the engine is warmed after 20 minutes of driving, and look at the color, the level, shine the fluid in a light source to see if any flakes are present. If it doesn't look all that well, get it flushed including the torque converter and refilled with Dexron VI and see if your shifting improves. You don't have much to lose anyhow by draining the fluid for new, a failing transmission is already in your hands. If it does improve for the first 500 miles, and make sure you take it easy during that time, then I persist it is the fluid pressure switches. If not, if your drive is jumping more than a kid in a bounce house then I would suspect slippage. The shifts won't immediately fixed, it''l come back after 400 or 500 miles being changed but they will be smoother so keep that in mind. Also, how many miles are on the car? 60-90,000 miles I presume?

https://youtu.be/KlFrNZYl9oo

Video is what to look for, below is the 989 code, and a simple guide to the color of trans fluid in case you or anyone else doesn't watch the video.



Sorry for a big post but this is important to know.
 

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I have had mine back at the dealership twice for this issue. Still does the same thing as you describe. I plan on taking it back in a third time to finally get it resolved. Here is what they say they repaired:

1. CONTROL VALVE LOWER BODY AND UPPER BODY REPLACEMENT

2. 3-5-REVERSE AND 4-5-6 CLUTCH HOUSING OVERHAUL

3. SUBLET REPAIR
 

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I have had mine back at the dealership twice for this issue. Still does the same thing as you describe. I plan on taking it back in a third time to finally get it resolved. Here is what they say they repaired:

1. CONTROL VALVE LOWER BODY AND UPPER BODY REPLACEMENT

2. 3-5-REVERSE AND 4-5-6 CLUTCH HOUSING OVERHAUL

3. SUBLET REPAIR
So the dealer isn't even doing the work, they sublet to a transmission shop?
 

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Discussion Starter #9
Thank k you for the great information! I will get it scanned and for from there!!


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Thank k you for the great information! I will get it scanned and for from there!!


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3800 for a rebuilt GM installed in 1 day solved all my problems :)
 

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I've got 55k on mine (2017 LT2) and have had the same transmission issues since I bought the car (bought with 40k). Everytime I have brought it in for service (at two different dealerships) they have told me there is nothing wrong and that there are no error codes so they can't really do anything for me other than do a relearn to "adapt to my driving". Glad I bought CPO though, because eventually a code is gonna have to pop up because it keeps getting worse. I also get weird downshifts when braking (if I brake to a stop from anything over 35-40 mph you feel the car downshift right before your almost completely stopped, its a very noticeable jolt).


I am actually picking my car up later today from the dealer - I had them check the transmission (and like I said found nothing but did a relearn) and they also replaced the water seals in the trunk (had water pooling in the spare tire compartment), both the rear shocks, and my exhaust intake manifold under the bumper to bumper warranty. Also had to do the front brakes, which for OE is $379. I love the car but man has it had some problems in my first year of ownership, its not looking very promising for the future (but hopefully she proves me wrong).
 

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I also get weird downshifts when braking (if I brake to a stop from anything over 35-40 mph you feel the car downshift right before your almost completely stopped, its a very noticeable jolt)
This car has a brake assist feature that kicks in on semi aggressive braking or downhills. This is completely normal. Even worse than what you just described is while you are in this assist mode and the light in front of you turns green and you start to accelerate sometimes it slams into the next gear.
 
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