Can't replace TCM on 2016 Mazda6 without replacing entire transmission?

[Snorting2.5]

OP, I would definitely look into having that done.

 

[LarryLondon]

Unsure if you've moved forward or not but I will also say that the tcm is indeed built into the valve body and the valve body is likely the issue. I have a 2016 Mazda 6 and the tcm is on the fritz. It will throw at, parking brake, engine, traction control lights randomly, go into limp mode randomly, and have the start button flash red and refuse to start occasionally. Every code, from engine light to the abs code is all tcm failure or lost communication with tcm. And it is an entire valve body and tcm assembly that needs replaced. I've reset the transmission, I've unhooked the battery, ECT. It'll drive fine for a week then freak out again. I even replaced abs sensors in case they were reading improperly and confusing the computer. My Mazda dealer says they've never replaced a valve body or tcm in these cars but can do it. Aamco says they can do it as well. The issue is it will need programmed to the vehicle it is installed in. They are vin locked. It can be replaced without replacing the entire transmission. I attached photos of the codes I have, if you don't have similar codes I don't think it'd be your tcm necessary. .

Thanks for that, good to know.

At this point I'm still driving the car and there has been no change to the behavior after 2 months.

I've still never had any codes, any transmission issues, any warning lights or any problems other than delayed engagement with a slight shudder when going from P to D on a cold engine. Other than that the car is still driving normally and the delayed engagement seems to be a minor isolated issue.

So I'm just continuing to monitor it and keep my options open. Replacing the valve body and TCM is over $2000 and I would probably pay that if I were sure it would fix the issue.

 

[Snorting2.5]

Valve body replacement will fix it.

 

[ceric]

OP,
If I were you...

1. I would drain-n-refill ATF a few times (2-3 times, you it once already) to clean up old fluid. I bet you never had it replaced before.. not the 1st owner either. So, it's over-due. Every drain-n-refill only gets to less than 1/2 of the fluid. Don't flush it.
2. I would reset the AT software by discounting (-) terminal for 30 mins and reconnect it. The entire transmission software will be reset and relearn your driving all over again.
3. if (1) and (2) do not fix it, I would trade it in to dealers of non-Mazda. Go there when your Mazda6 is fully warmed up. Let dealers deal with it. Yes, I won't feel good selling it to any private party. I have no problem selling it to dealers. They are professional.

 

[Silly Wabbit]

I'd highly recommend op to perform AT relearn which is on the first page of this thread. A simple battery disconnect will not relearn.

 

[sinistriel@]

OP,
If I were you...

1. I would drain-n-refill ATF a few times (2-3 times, you it once already) to clean up old fluid. I bet you never had it replaced before.. not the 1st owner either. So, it's over-due. Every drain-n-refill only gets to less than 1/2 of the fluid. Don't flush it.
2. I would reset the AT software by discounting (-) terminal for 30 mins and reconnect it. The entire transmission software will be reset and relearn your driving all over again.
3. if (1) and (2) do not fix it, I would trade it in to dealers of non-Mazda. Go there when your Mazda6 is fully warmed up. Let dealers deal with it. Yes, I won't feel good selling it to any private party. I have no problem selling it to dealers. They are professional.

Battery disconnect will not relearn the transmission behavior and learned values. Its written into the ROM of the TCM and needs to be told to begin again.