I have a 2008 mazda 3, 2.3l with the 5 speed automatic. 119,000 miles on it.

Started it up one day and had CEL, AT, and TCS lights on with a very hard shift into reverse. Did some research and sent the tcm off to UpFix for repair. Needed several repairs. Got it back, relocated it to the brake lines and off the top of the transmission. Started it up, other lights were off but AT light remained and hard shift persisted.

Sent it back to UpFix, who made a couple additional repairs under warranty. While it was gone and being repaired, I did a drain and fill of the trans fluid (got about 4 quarts of fluid out, looked like it had never been done). Also replaced the filter and all 5 shift solenoids and EPC sensor. Used a new filter and reman'd oem solenoids from ebay. Got the tcm back and reinstalled for second time. Refilled fluid.Finally started it up today. AT light is still on, still hard shift on reverse. Haven't left the driveway for fear of causing further damage. Any ideas what could still be causing this after repairing the tcm, replacing about half the fluid, and new filter, solenoids?

Had no prior issues or symptoms. Shifted really smooth prior to all this. Just happened out of the blue, which makes me think it's something electrical, i.e. tcm, solenoids, etc. But I did all of those.... Any help would be greatly appreciated before I tow it to a trans shop and go broke. Thanks!

 

Well , sorry to say your transmission shifting issues were not diagnosed properly from the start. Now with all the parts changed i is going to be more difficult to find the original problem.
You might consider looking for a specifically advertised transmission service shop that can at least do a basic diagnostic check and give you a better idea what the problem is.
The challenge you will have is when and if you tell the shop what you already did what they are going to give for and diagnostic and physical inspection estimate?

If you had a quality professionally diagnostic scanner you could at least go in and clear all the DTCs as well reset the I/M monitors and check for permeant DTC and also have a look at the centerers that relating to the begining of this issue.

I did not read that you tried the Mazda service steps at times needing to do when changing transmission parts and TCM's?
Look up :
reset the transmission control module

Prior to doing this you MUST health check the battery and the battery cables at the battery and at their attaching points.

BECAUSE YOU ARE A DIY THE GOLDEN RULE IS ALWAYS CONFIRM A PART HAS FAILED BEFORE RANDOMLY ASSUMING BASED ON LIMITED INFORMATION AND DTC THAT THAT IS THE CAUSE OF THE PROBLLEM. DOING THAT WILL IN MANY CASES ADD NEW PROBLEMS TO THE YET UNRESOLVED ONES.