2014 Chevy Sonic - Transmission Control Module (TCM) Issue

[sebDill2014Sonic]

Hello everyone,

hopefully you are all having a great day, so far.

I'm new to this forum and would like someones opinion / advice on the issue I am having with my 2014 Sonic LT - 1.8l:

So, sometimes, when driving, the car seems to shift from DRIVE to PARK on its own while going full speed. At the same time, the Traction Control light comes on on the dash and the door locks go bananas.

When I had AutoZone read the codes, it gave me U0101 - No Connection to the TCM.

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So I took it to the local Dealer and they advised me to change the entire Transmission, which I believe is a complete rip off.

So my thoughts on this are:

Since the ECM seems to receive a signal from the TCM (assuming the wires are all good), shouldn't I just replace the TCM itself? (This is actually what the dealer diagnostic paper shows - funny that they want me to swap the whole tranni ).

I just wanted to see if anyone has experienced the same issue and has some advice.

Furthermore, I wanted to know if you have to drop the whole transmission to actually replace the TCM.

Thanks a lot for all the help in advance.

Sincerely,

S.

 

[Pirate Luke]

I posted this a while back, it might clarify some of your questions:
http://www.sonicownersforum.com/for...ormative-6t40-automatic-transmission-pdf.html

According to a member in that thread link, you can definitely switch tcm modules/transmissions without issue or reprogramming. If you have a tune, you will need to have two separate files going forward since the VINs will differ. Depending on the your mileage, it may be worth it to just get a low mileage used one from eBay or at a pick-a-part and swap it in.

Whatever you decide to do, please inform us here of the progress/what you learned. It's super beneficial to others that need to do something like this down the road.

 

[sebDill2014Sonic]

Dear Pirate Luke ,

Thanks for the info. I will let you guys know how this all worked out.

FYI...here the link on how to change the TCM:

Chevrolet Sonic Repair Manual: Control Solenoid Valve and Transmission Control Module Assembly Replacement - Transmission Control - Internal Combustion Powertrain Control - Powertrain

Not sure if I actually need the entire transmission.

Regards,

S.

 

[216SonicBoomer]

Good post

 

[lmathews2405]

This is the EXACT issue I am currently having with my 2014 Sonic. The dealership replaced the shifter as the old one would sick on me. Unfortunately my Sonic is back at the service center because the same issues are happening even after replacing the shifter. Any update on how yours turned out? I originally had the TCM issue and got the same code, but my mechanic could not diagnose any issues.

 

[Srb316]

I have the same issue. 2014 chevy sonic 1.8. Rough start, traction control light turning on and U0101 (lost comm with tcm). Car clicks and it doesn't show what gear I'm in on the display. Drives fine, but sometimes it jerks really hard, shoots up to 4500 rpms, doesn't accelerate for a few seconds, and the locks go crazy. Went to the delarship and they think it's the tcm.

 

[Gen78148]

I have the same issue. 2014 chevy sonic 1.8. Rough start, traction control light turning on and U0101 (lost comm with tcm). Car clicks and it doesn't show what gear I'm in on the display. Drives fine, but sometimes it jerks really hard, shoots up to 4500 rpms, doesn't accelerate for a few seconds, and the locks go crazy. Went to the delarship and they think it's the tcm.

Having same issue did yiut resolve it. How did u fix it

 

[Srb316]

Having same issue did yiut resolve it. How did u fix it

Yes I did. It cost me nothing. Basically, you have to reset the car computers. When you unhook the battery, it doesn't fully reset it. So, if I remember correctly, you have to push down on the accelerator fully for like 10 or 20 seconds, then turn the key fob to the position just before the one that starts the car up whilst still pushing down on the accelerator, wait a couple minutes just to make sure, then turn the key to the off position while still having your foot on the pedal. Then you can take your foot off and key out and then start your car up. I would look up how to reset chevy computer online just to make sure because I could have forgotten a step. It's been a few months since I fixed it. It took me 2 times of doing this to fix it. Just make sure you drive your car after you fix it to sort of reprogram and relearn your driving style. If this doesn't work, which I think it will, then I always heard you can drive it as a manual to bypass the tcm. I don't know if that's true, but that would be the next cheapest option. Tcm's don't really go bad. If all else fails, I would check to make sure your battery is running at the right voltage and your alternator is putting out too many or to few amps. Also check your tcm fuse in your fuse box to see if it has any ohms. Also check your wiring running up to the tcm to make sure it isn't chewed by mice. It's hard to diagnose a tcm problem but resetting computers is the easiest and cheapest first step. Good luck!

 

[JTee2017]

Good to know . . Thanks!

 

[LightingLindsey]

Same thing with my 2014 Chevy Sonic LT .
Weird choppy idle sometimes, and recently wouldn't shift properly or show on dash board- Again only sometimes.

Code is U0101. Getting the TCM looked at now

I did replace my shifter knob a few years ago cause it just snapped out if no where on the highway. Ordered the part off Amazon for $30 & took me 15min to install.
And also had to replace a purge valve ( I think I was overfilling when gassing up which caused that)

Other than that the car has been good to me, bought it brand new. Love the lil thing.

 

[Bcxiv]

Same thing with my 2014 Chevy Sonic LT .
Weird choppy idle sometimes, and recently wouldn't shift properly or show on dash board- Again only sometimes.

Code is U0101. Getting the TCM looked at now

I did replace my shifter knob a few years ago cause it just snapped out if no where on the highway. Ordered the part off Amazon for $30 & took me 15min to install.
And also had to replace a purge valve ( I think I was overfilling when gassing up which caused that)

Other than that the car has been good to me, bought it brand new. Love the lil thing.

Hi did you end up figuring out how to fix it?? I’m currently facing the same issue and code

 

[Bcxiv]

Good to know . . Thanks!

Did this solve your problem?