Transmission type and Transmission Solenoid

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Fluffycakes2020

Member
So I drive a 2012 sonic 1.8 with auto tranny that literally just hit 100k miles today. Just recently I have been having shifting problems and a few other problems literally after I changed the valve cover for the new pcv valve. So what its doing is 2 things, taking a long time to down shift while driving 70+mph and staying in gear longer than before, and when driving and going to speed up to pass a vehicle, it jerks and doesnt shift when it needs to and makes the car slow until it finally shifts. Now the second one doesnt happen all the time but the first does. Will it need to be replaced or can I change the solenoids inside the transmission? Also, how do I find out what type of tranny the car has so I am able to find the right parts? Ive seen youtube videos on the solenoids inside and how to remove them which looks simple, and the problems im having seem like the cause of a bad solenoid. Quick note, I changed the transmission oil about a month ago.
 
G

Gobinator98

Member
Fluffycakes2020 said:
So I drive a 2012 sonic 1.8 with auto tranny that literally just hit 100k miles today. Just recently I have been having shifting problems and a few other problems literally after I changed the valve cover for the new pcv valve. So what its doing is 2 things, taking a long time to down shift while driving 70+mph and staying in gear longer than before, and when driving and going to speed up to pass a vehicle, it jerks and doesnt shift when it needs to and makes the car slow until it finally shifts. Now the second one doesnt happen all the time but the first does. Will it need to be replaced or can I change the solenoids inside the transmission? Also, how do I find out what type of tranny the car has so I am able to find the right parts? Ive seen youtube videos on the solenoids inside and how to remove them which looks simple, and the problems im having seem like the cause of a bad solenoid. Quick note, I changed the transmission oil about a month ago.
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The transmission for the 2012 sonic with 1.8L is a 6T30 trans. The 1.4L has the 6T40.

As for the the problems you are describing, I have had the same issues since I got the car(about 58,000 miles ago). Car has almost 157,000 miles on it.

When does your car shift late? Does it slam into gear?

Mine, for example, shifts late going into 3rd then really shifts late going into 4th, and when it shifts into 4th it really slams into gear. I’ve noticed that this problem has only gotten worse the longer I’ve had the car. If your problem is like mine then it could possibly be a solenoid but the more likely issue is with the 3/4/5 + Reverse clutch pack is bad. That’s a common problem with the 6T30/6T40 transmissions.

Is your transmission fluid burnt? Have you had someone with a scan tool check the operating temperature of the trans? One day I was doing highway driving and the trans temp got as hot as 220°F, which is way too hot and the fluid starts to degrade after 200°F usually.


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Fluffycakes2020

Member
It mainly down shifts late and I feel like the rpms are way to high for the gear it's in. It's gotten as high as 4k which before I don't think it was ever that high. It seems to stay in 2 gear I believe to long so when I go to stop it revs high then finally down shifts in to 1st. I'll try and get a video of it shifting to show you better. The fluid was black from what I can remember but I haven't checked it lately I have a obd2 scanner so I'll have to see if it shows temp for the tranny.
 
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Gobinator98

Member
Fluffycakes2020 said:
It mainly down shifts late and I feel like the rpms are way to high for the gear it's in. It's gotten as high as 4k which before I don't think it was ever that high. It seems to stay in 2 gear I believe to long so when I go to stop it revs high then finally down shifts in to 1st. I'll try and get a video of it shifting to show you better. The fluid was black from what I can remember but I haven't checked it lately I have a obd2 scanner so I'll have to see if it shows temp for the tranny.
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Sounds like the same exact problem I have. Mine unfortunately doesn’t have any codes for the TCM, which usually means the solenoids are fine because they would definitely trip a code. I did find information on how the engine speed relates to the gear the transmission is in. In gears 1-5, the engine can rev as high at 7000 rpm. In 6th gear, the engine can rev as high as 5,800 rpm.

Usually black fluid is a sign that it needs changed. Did the fluid have a smell to it? Like burnt smell?


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Fluffycakes2020

Member
When I changed it It was black and smelt burnt but that was about a month ago so not sure how it is now. And I have no codes for tranny either except for car running lean and had some knock sensor codes too. Cars is going to mechanic tomorrow night to help diagnose the problems the car is having. Especially the traction control light and rough idle problem
 
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Gobinator98

Member
Fluffycakes2020 said:
When I changed it It was black and smelt burnt but that was about a month ago so not sure how it is now. And I have no codes for tranny either except for car running lean and had some knock sensor codes too. Cars is going to mechanic tomorrow night to help diagnose the problems the car is having. Especially the traction control light and rough idle problem
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Sounds like your trans is running hot and burning the fluid. Might even have some bad clutches in the trans causing the late/rough shifts.


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F

Fluffycakes2020

Member
I'm gonna make a video of it shifting so you can see. And I'll see if my scanner shows the tranny temp. I'll also look at the tranny fluid and see
 
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Gobinator98

Member
Fluffycakes2020 said:
I'm gonna make a video of it shifting so you can see. And I'll see if my scanner shows the tranny temp. I'll also look at the tranny fluid and see
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Alright. I changed some of my fluid a few months ago but it didn’t help the shifts. Only thing that happened was the transmission ran a bit cooler, still not great. So I bought a used 2015 sonic automatic transmission to replace the one in my 2012 sonic. Gonna pay to have the 2015 one rebuilt and installed into the car.

There was a couple other threads on here stating they had done the same and didn’t have to program anything or change modules. Just plug and play. Plus they said the shift quality was so much better and made the car more enjoyable to drive.


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Fluffycakes2020

Member
Yea I would rather replace it but scared of the cost using a transmission shop. I'm just hoping the repair is something that can be replaced inside or something I can do.
 
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Gobinator98

Member
Fluffycakes2020 said:
Yea I would rather replace it but scared of the cost using a transmission shop. I'm just hoping the repair is something that can be replaced inside or something I can do.
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Yeah I hope the cost isn’t huge but that’s the risk I’m willing to take as I don’t have the time to tear down and rebuild it myself even though the service manual for these transmissions is 40 dollars. If you end up using a transmission shop, make sure they are credible.


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Fluffycakes2020

Member
Yea the problem with me is I can't afford to get a new car and depending on if it needs a new tranny and how much I may not be able to afford that so it's gotta be a decent price. I've been screwed by a transmission shop before and found a good reliable one with really good reviews.
 
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Gobinator98

Member
Fluffycakes2020 said:
Yea the problem with me is I can't afford to get a new car and depending on if it needs a new tranny and how much I may not be able to afford that so it's gotta be a decent price. I've been screwed by a transmission shop before and found a good reliable one with really good reviews.
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I was in the same boat a couple years ago when I had to replace my motor at 125,000 miles. Was driving 85 on the interstate then went to pass someone and the check engine light flashed and then stayed on. I wanted to get a new car but couldn’t get approved for a new loan, so I had to refinance and replace the engine.

I’m sure you’ll find a good shop to go to. I still have to find one in my area to do it. I got a good mechanic that could install it. That mechanic is pretty cheap. On my old car, it cost me less than 400 to have my whole brake system repaired/replaced and a new muffler installed.


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F

Fluffycakes2020

Member
So as I was driving the car seems to shift normal while accelerating. It seems to stay in 5 or 6 gear for along time before downshifting. Downshifting is where it seems like it has a problem or at least I think so. The video might not show it very well but hopefully you it helps. And my scanner doesn't show tranny temp.

https://streamable.com/h2i9md
 
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Gobinator98

Member
Fluffycakes2020 said:
So as I was driving the car seems to shift normal while accelerating. It seems to stay in 5 or 6 gear for along time before downshifting. Downshifting is where it seems like it has a problem or at least I think so. The video might not show it very well but hopefully you it helps. And my scanner doesn't show tranny temp.

https://streamable.com/h2i9md
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Mine does the same exact thing. So you have not noticed any up shifts that take longer than they should? Mine won’t shift into 3rd and 4th until about 3700 rpm, which is way, way too late compared to the other gears.

I’d still try to find someone that could check your trans temp at full operating temp. Fortunately for myself, I can check the coolant and trans temp with my radio. (Installed aftermarket unit and idatalink maestro.)


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Gobinator98

Member
Fluffycakes2020 said:
Yea im dropping it off tonight so he can check the other problems im having tomorrow. Need this car to last me another couple of years.
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Good luck and keep us posted. I know mine will last at least another 5 but I know I’m not buying another Chevy again


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G

Gobinator98

Member
I loved them too. Unfortunately they discontinued them just like Ford did with all of their sedans. Looks like I’ll be going with a Toyota or Honda hybrid. Maybe even a fully electric car.


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