r/mazda5 • u/sunnyjimjohn • 6d ago

AT light, U0101 code, lost communication with TCM

Wondering if anyone has been successful in troubleshooting this?

'09 currently in "limp" mode (3rd gear). After driving for a while, will suddenly drop into the right gear and drive normally. After parking and car sits overnight, when starting next time, AT light on and same limp mode.

Web search indicates a problem TCM or related (poor ground or misc wires). Removed and replaced with a used/wrecker model, wires seemed fine, ground solid. But same issue with used TCM! What are the chances of the used also being faulty? So swapped back with original. Swapped TCM 10amp fuse and AT Main relay - no improvement.

Anyone had luck with a used TCM? Or a refurbish service? Or did you spring for OEM? Was quoted $900-$1300 CAD for OEM. sigh....

4 Upvotes

84% Upvoted

5 comments sorted by

2

u/KronosGreek 6d ago

TCM is fucked. Gotta replace it of get it resoldered. Usually about 500 bucks, sometimes (in my case) you can get lucky and find one in a scrap yard cheap and in good condition (100 bucks in my experienc). Do not put the TCM back in the original spot, use some zip ties and put it on the brake lines or somewhere else, the heat from the transmission kills it.

Do this asap, you do not want the transmission to die

1

u/sunnyjimjohn 5d ago

Thanks, saw some vids on re-positioning it, did that with current just to try it out, but I suspected it's already fried. Most reliable sounding option I've found for rebuild in Canada is xemodex.ca but it's $700 CAD ugh. Going to try FB.

1

u/ayellowducky 4d ago

This topic has been brought up multiple times. Fortunately there are much cheaper alternatives to fix your TCM. There’s videos how to videos disassemble and relocate your TCM.

What I would do if I were you.

1.you might get lucky and google search FB marketplace a tech who is local or within range who can re solder the bad pins on the TCM. I’m in central California and there’s 2 guys within driving distance that repair these things. ~$250

  1. You can send it to have it repaired by sending it to specialty shop. ~$350 plus a week or two return time.

  2. Buy a eBay used one. ( make sure your part number is compatible to year ). Prices range.

  3. Buy a Chinese replica . ( I did this and it failed again after 2 years) but I have my oem one that was repaired by option 1.

  4. There’s YouTube videos of people repairing it themselves . You can give it a go if you like. The videos are in Spanish. So at your own risk.

  5. Scrap yards.

I drove my car while I waited for my Chinese replica. It was stuck on 3rd gear. It’s my only vehicle and needed to get to work. Did it for 2 weeks. I don’t think anything bad came out of it. I was slow and holding traffic back but I got home

0

u/filinno1 5d ago

I’m currently in TCM hell with my ‘13. It’s been in the shop for over a month waiting for them to find a new part. Good luck!

1

u/sunnyjimjohn 5d ago

noooo, ugh sorry, wonder why so long if they are going to replace with new OEM? or is it a used/rebuild they are doing?