I let the smoke out of the automatic transmission of my 2007 Mazda 3 and it’s at Aamco now. What apparently happened is I got a tear in the boot of the passenger side CV axle, which let out the transmission fluid. The Aamco guy said my transmission is ruined, which seems fairly obvious to me, so I found a remanufactured one online for a better price than what Aamco would offer. They agreed to install it anyway and even with their labor estimate I’m saving a good amount of money.

The trouble is that now that they’ve started work and have removed the old transmission, they’re telling me that the old TCM, speed sensors, fluid pressure transducer, and neutral safety switch have also gone bad and cannot be reused. Based on a previous experience, I believe they are correct about the neutral safety switch, but I am doubting the diagnosis on the TCM. I asked how they made this determination with the TCM and the reply via SMS was “WE DETERMINED IT WAS BAD WHEN SCANED WITH THE COMPUTER THERE WAS NO COMMUNICATION WITH THE TCM”. After I let the smoke out and the AT light came on, I limped home in fourth gear and then scanned for codes. I came up with P0733 (Transmission Gear #3 incorrect ratio) and P0894 (Transmission Component Slipping). If the TCM was not communicating, wouldn’t I have gotten a U0101 code?

I’m not trying to be a cheapskate, but a replacement TCM isn’t cheap and I don’t want to spend more than necessary.