Removing a TCM from a 2010 Mazda 3i.

Intro is a bit blurry, but rest of the video is detailed and specific for removing this simple piece.

Start by removing the battery from its holding container.

Within the battery compartment's case, there are 3 bolts you'll want to remove.  A 10mm socket will work here.  You may want to use an extension on your socket wrench as it's a bit tight to work on there.

Once that is removed (or before is fine), you will want to lift the lift for the connectors in your battery compartment.  These can be removed easily with a screwdriver being driven between the white latch and the holder, applying a slight twist to the screwdriver while lifting up on the white latch.  Detach both connectors and put them to the side.

To remove the battery holder, you may want to remove the front plastic plate of the holder.  There are a handful of cables that may have snap-ins that you will want to pry out with a screwdriver.  The casing itself has circle cutouts for larger wires to run through.  Make sure you remove any cable attached to the front plate.  Once that is out, you will want to pull out the battery holder.  I've seen videos of people removing from the face first, however I had better luck taking the back side out first while slightly bending the plastic away from the car frame.

Once that is out, your TCM will be visible.  It is located directly below the battery holder and has ridges on it.  It is connected by 3 bolts and 1 connector.  The bolt on the inside (closer to the middle) is ccovered by a large cable.  This can be removed without tools by wiggling and lifting straight up and setting that cable to the side, making the bolt visible.  This specific bolt will require a deep 10mm socket as it has extra length.  The other 2 bolts are removable with a short 10mm socket wrench, there should be enough remove to get a tool in to remove them.  The connector is attached in the same fashion as the other connectors- use a screwdriver to slightly move the white handle from the locking latch and pull it back.  It should come out easily.

Once all that has been removed, your TCM should be free to be removed and you are good to go.  I've seen many places mentioning you should not put the TCM in the same place it is removed from.  It's a common issue with 2010 Mazda 3s that the TCM overheats because it is placed directly on the transmission.  Instead of putting it back there, consider zip-typing it to your brake lines.