95 Rodeo, 110k miles, auto transmission. Recently I've stopped driving daily but when I do drive it on local streets with stop and go, the check transmission light flashes on and (according to the manual) it goes into backup mode where I have to shift the gears manually. I turn the car off and back on and it gets rid of it, but I just did this and minutes later it happened right away again.

Any insight as to what's going on that would cause this? Is the tranny going, slipping, etc.? I've checked the ATF level and refilled it (wasn't really that low).

Isuzu dealers are few and far between nowadays so I'm not sure if a typical shop would know what to do with a 'check transmission' light as I don't think other vehicles have it. Any insight would help... thx.