2008 Mazda5 Transmission Control Module Replacement *Experience*

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2008 Mazda 5 & 1990 Mazda Miata
Just joined Mazdas247, so hello everyone! I want to share my experience about replacing my Transmisison Control Module:

The vehicle is a 2008 Mazda 5 2.3l automatic. Not certain what trim level. Initial problems were random and infrequent hiccups in power, AT light turned on with code U0101 "Lost communication with Transmission Control Module. Felt like the car was locking up in some way. What actually is happening is the Transmission is trying to go in limp mode which is only 3rd gear. Not fun when you are on the highway! First thought was the automatic speed sensor. Replaced it, but still experienced the same symptoms. Did some more digging around, found out it could be the transmission control module going bad.

Read a few threads on here, determined the next step was to replaced the TCM itself. When I pulled my TCM, it's part number was "L39C189E1B". The replacement part I purchased from CJ Wilson Mazda was "L39C189E1E". I cannot find the thread, but someone theorized that the difference in the part number is either an update in hardware/software from the later year models which didn't have transmission issues (which maybe Mazda is aware of the defunct units?).

Installation was pretty straight forward. It's located underneath the battery in the engine bay. One of the bolts was a bit hidden, so I used a hand wrench. Restarted the 5 only to have a stall at a gas station; Forgot to let the engine relearn it's idle for 5 minutes (Whoops! A lot has changed from my 90 Miata to my 08 m5). Be sure to let it relearn the idle!

6 months later on the fix and it's still functioning! No issues to report Total cost was $455.11 for the TCM and $47.33 for the speed sensor. (I recommend CJ Wilson Mazda for their discounted price).

Let me know if you have any questions, I'll gladly answer them. This post is for record purposes and hopefully it's useful for you!
 
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2009 Mazda 5
163,XXX Miles. 158XXX when this happened. 5k miles later, still no issues to report.
Hi, i have the same issue, 2009 Mazda 5, buybut dealer says there is some programming to be done on top of replacing the module. It doesn't seem you had any programming to do, jist swapping the part. They want to charge 1000 for part and labor.

Any advice?

Thankyou
 
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Mazda5
My dealer wants over 5,000 to do this job and thinks the whole transmission may still need replacement after TCM. They told us to trade in the vehicle rather than fix it. I think they just want to sell cars not help us. They also will not pass our inspection because of a light cover thats broken even though it has no way of causing the light to stop working. They want over $500 to replace this cover.
2010, 116k miles.
 
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2012 Mazda 5
My dealer wants over 5,000 to do this job and thinks the whole transmission may still need replacement after TCM. They told us to trade in the vehicle rather than fix it. I think they just want to sell cars not help us. They also will not pass our inspection because of a light cover that*s broken even though it has no way of causing the light to stop working. They want over $500 to replace this cover.
2010, 116k miles.
Well, you can do the light cover yourself probably for a few bucks if not interested in their quote, or find shade-tree mechanic for that.
Try a second opinion about tranny, there is always change is it screwed.
 
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2008 Mazdaspeed 3 and 2010 Mazda 5
Hi, i have the same issue, 2009 Mazda 5, buybut dealer says there is some programming to be done on top of replacing the module. It doesn't seem you had any programming to do, jist swapping the part. They want to charge 1000 for part and labor.

Any advice?

Thankyou
I did not have to program anything when I replaced mine.
 
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2008 Mazda5 GT
Does anyone still have their old/broken TCM? Would you send it to me instead of the dump? I'd like to open one up to see what's inside that causing these failures.
 
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2008 Mazda 5 & 1990 Mazda Miata
Bumping this

The part you listed is for the 2012-2015 models. I would wonder if something is programmed differently because they have a larger engine?

https://www.mazdapartswebstore.com/...ule-TRANS-CONTROLLER/48741329/L5E4189E1E.html
I greatly apologize, but I have listed the wrong parts. Looking through my old phone's photos, I have updated the original post with the correct part numbers. The part number you should be looking for the 2008-2010 Transmission Control Module is L39C189E1E. That is the most up to date Transmission Control Module I purchased.
 
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2008 Mazda 5 & 1990 Mazda Miata
Does anyone still have their old/broken TCM? Would you send it to me instead of the dump? I'd like to open one up to see what's inside that causing these failures.
Ugh, I'm so sorry, but I definitely threw mine away when I got my new part. There is the website mazda-tcm.com that specifically calls out the problem at hand. What I can do though is post photos of the old and new TCMs side by side. You'll see on the old one that there is a thick coat of dirt/potential corroded electronics covering the bottom side.

Transmission Control Module by Monk Ratava, on Flickr

Transmission Control Module old v new by Monk Ratava, on Flickr

Transmission Control Module by Monk Ratava, on Flickr
 
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2008 Mazda5 GT
Thanks for positing the pics and pointing out mazda-tcm.com. The TCM module looks like a board housed inside a heat sink with anti-vibration/weather seal coating. Do you have another close-up pic without glare/reflection? Now I'm even more sure these failures are likely due to some common things like loose joints or bad capacitor, likely due to heat, since mazda-tcm.com provides the service to recondition your old one with "high-quality electronic components only and a special compound to fill MAZDA TCM".


Assuming their list is correct, you want the latest model number.
Mazda 5 USA 2.3 2008-2012
L39C189E1
L39C189E1A
L39C189E1B
L39C189E1C
L39C189E1D
L39C189E1E
L39C189E1F
L39C189E1G
L39C189E1H

Mazda 5 USA 2.5 2012-2016
L5E4189E1
L5E4189E1A
L5E4189E1B
L5E4189E1C
L5E4189E1D
L5E4189E1E
L5E4189E1F
L5E4189E1G
L5E4189E1H
 
Aamco

I did not have to program anything when I replaced mine.
I'm getting the same statements from my maintenance shop. They say there is specific programming to be done that needs special laptop and software. Sounds like a crock to me.

Can someone just confirm that if this part is purchased, it is just plug-and-play (or maybe just a 5-minute idle program)???

2008 Mazda5 2.3L Touring
https://www.mazdapartswebstore.com/oem-parts/mazda-trans-controller-l39c189e1e
 
I'm getting the same statements from my maintenance shop. They say there is specific programming to be done that needs special laptop and software. Sounds like a crock to me.

Can someone just confirm that if this part is purchased, it is just plug-and-play (or maybe just a 5-minute idle program)???

2008 Mazda5 2.3L Touring
https://www.mazdapartswebstore.com/oem-parts/mazda-trans-controller-l39c189e1e
Not sure if you're still on the fence with this, but I just replaced the TCM on my 2008 Mazda5 Sport with 144,000 miles. The car was throwing the PO753 code, dropping into limp mode, etc. I purchased a new unit (part no. L39C-18-9E1E) and installed in about an hour.

I didn't do an idle program and just drove it. Only a day and about 30 miles so far, but no problems to report as of yet.
 
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