2012 Mazda5 Automatic Transmission Trying to Downshift While Driving
Been having this issue for a couple months and it's steadily getting worse. Most often it occurs while cruising, not under heavy load. It does seem to happen after harder driving (either a spirited bout on the commute home or after hauling probably too much mulch in the back), but never during.
At first it would be momentary, almost feeling like it was locking up for a split second, but I found out it was trying to go into third gear. The most recent occurrence was the worst. Kind of jumping all over the place, AT light on (it comes on every time but turns off after a bit) and even had the gear indicator light on the dash turn off completely. I've found that switching to manual mode is usually enough to get me home, but that was only mildly successful this last time and even going into neutral didn't stop all issues completely. Fortunately I was quite close to my destination and with no one behind me I was able to get it in neutral and coast for 1/4 mile or so and then didn't have any problems for the last ~1.5 miles til I could stop. No issues this morning coming to work.
Like I said, it can happen after some harder driving, but it's pretty random. The first time it happened was while gently driving home on a cool night at low-moderate speed (40-60mph). No ambient heat to consider, no hard acceleration, nothing. Transmission fluid level is fine, and color doesn't look bad. I don't actually know if the Mazda ATF that's (probably) in it is red or another color, but it's far from black, more of a slightly greenish brown, like new motor oil. I will say I am generally a more spirited driver, but I'm not hitting the limiter all the time or flooring it from every stop light. I beat my cars a fair bit but I take care of them and have never blown anything up in the past with my antics.
Could it be a TCM going haywire? Can I scan for codes when the AT light is off? It would be very difficult to repeat the issue if I tried for a mechanic and only happens once every couple hundred miles at most. I'm just concerned because I need the car and it seems to be getting worse.