Hey guys,

I took my car to mechanic after weird intermittent transmission issues. They said TCM need be replaced. Cost: 1200$

They said I could take it out and send it in for repair for 3-400$.

I took the air filter box out and the battery and the box that holds the battery because the only instructions I could find said it would be under there.

It is not...

Is there somewhere I can find or buy a diagram for my particular vehicle to find where this thing is?

I have viewed a dozen videos on youtube, but none are exactly my model of the car because when I get to the point where they find the TCM/TCU nothing is there.

The full specs are:

2013 Mazda Mazda3 4dr Sdn Auto i Sport

Thanks for any help, I am pretty stuck at the moment...

 

2013 BL Mazda 3 with the 5 speed transmission, has the TCM mounted on top of the transmission, hidden underneath the battery box.

6 speed appears to be controlled by the PCM.
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Hey thanks so much for taking time to answer!

I have a 6 speed, and found what I thought was an ECM attached to the battery box. If it's actually the PCM that would be great as that is pretty easy to access.

I'll see if I can find out if it is a PCM and not just and ECM and go from there. If you happen to know where I could find that information more definitively that would be great, but thanks so much for the help so far!

Attached is a picture of what could possibly be the PCM that I pulled off the battery box.

 

Hey man, I think this is indeed the PCM!

https://www.xportautoparts.com/oem-p...LTE4LTg4MVI%3D

This is good news and points me in the right direction.

Now I can put all this junk back together and hopefully send this thing out for repair.

Thanks again for pointing me toward a PCM!

 

Can some one explain why these TCM's cost this much?
Other mazda TCM models way cheaper.
Given the main cause of failure is where it is mounted due to heat; why hasn't there been a recall or class action law suit?

 

Hi - Did your problem fix.? My car is having some Transmission issues. I even could not find TCM underneath the battery. Even mechanic argued with me that it should be under the battery. I am unable to drive my car as it gives jerk when I accelerate it. Check engine and stability control light is on. This is Mazda 3i skyactive 2012 6T. Will this issue resolve if I change the PCM? Request your suggestion to help me

 

I am having this exact same issue. Code readers are not able to connect with the ECM and give a u0101 and a u0155 code. Were you able to fix this by replacing the ecu?

 

You should first verify that your ECM is bad. One person's vehicle problem is not necessarily the same as others. There are too many unlike variables.
If you don't want to risk wasting a lot of money, then pull you ECM and send it to a rebuilder/supplier and have them health check it for a small fee. If they find you at fault, then purchase one of their rebuilt/tested ECMs.
A few simple things that resemble a failing or failed ECM. A battery that is failing. Must have it professionally load tested. Poor connectivity of battery terminal and cables both on the battery and on the starter and chassis. Dirty, worn ECM connector's. These are a few of the overlooked few that could for some have them think they have a bad or failing ECM .

 

Alobster111 Welcome to the forum

 

The alternator is good and the battery is new. I have checked all the connectors and cleaned them with contact cleaner, the battery connectors have also been properly secured. I have successfully reflowed solder joints on computers before. I'm about to rip it open and do this if it isn't full of epoxy. This car has just over 100,000 miles and has been such a massive turd since my father has had it that i'm about to just roll it to the scrap yard.