1. UpFix FAQ's
  2. Automotive
  3. TCM Transmission Control

I have a 2010 Mazda 3 and I can't locate the TCM, is there somewhere else it could be?

It could be that your TCM is integrated with the PCM. 
If your Mazda 3 or 5 does not have the external TCM. Then first have dark or dirty transmission fluid drained. I recommend replacing it with fresh fluid and a new filter. Check fuses, back probe wiring, plugs, and pins. Make sure they are free from debris, dirt, grease/oil. Check your speed sensor and your oil pressure switch to the transmission as well.
 
Please check your battery cables and grounds, try the hard battery reset (guide attached) with both negative and positive terminals constantly touching for 30-40min and the battery removed.
 
Once you have completed the above steps, re-scan the car and follow the codes. If he has the same issue then the PCM may need to be replaced.