Hi Everyone! I am new to this forum and this is my first post so I apologize in advance if this is a well discussed topic. I bought a 2008 Mazda 3 Hatch for my son. It's been a really good car until some transmission problems as of late. Back in May, the car started having issues that felt like the transmission was slipping while accelerating and would shift hard but not past 3rd gear. The AT and Check engine light was on so we took it into a shop. They said the code was for a bad shift solenoid but after testing all of them and finding they were good they replaced the TCM. $1,200 later we had a great running car again until this week. My son called me and said the AT and check engine light was on again but after turning it off to check things out and restarting it the AT light went out and the car drove fine. He brought it to me and I checked the code. PO758 B Solenoid. I cleared the code and he drove the car for another 3 days without issue. Yesterday on the way to work the AT and check engine light went off again and it went into limp mode. We had it towed home and after restarting it the AT light went off again and once again the code was PO758. I proceeded to pull and bench test all the solenoids. The ohms are all within specifications and they all click when hit with voltage. I am thinking TCM again but I hesitate to replace it because it's only 3 months old. It's OEM from Mazda with the E update. Is it possible this thing could be bad?
Last edited by dlcraig1; 08-18-2018 at 02:25 AM.
UPDATE! Turned out to be the TCM. Very surprised since it was new OEM unit from Mazda but had it confirmed by transmission shop. Dealer warrantied replacement and shop warrantied all the labor to replace.
2nd Update! So.......it seems like unless I am the most unlucky car owner in the world, it's not the TCM. it's back to throwing codes and going into limp mode. It's been back in the shop for 3 weeks now. They thought they had it figured out and changed out the B solenoid then it f'd up again. Then they changed out the A solenoid and wanted to test it. That was Friday and i haven't heard back which is most likely a bad thing. I'll update again later. Anyone ever respond to these posts or am i just talking to myself?
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Originally Posted by dlcraig1 View Post