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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!
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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