Automatic Transmission not shifting to third

I have a '96 3.1L Monte Carlo with an automatic transmission. I’ve had it since 2001, and it’s been great. The other day on my way home, about 2 or 3 miles away from home I noticed that it was revving at around 5k instead of shifting somewhere between 3 or 4 (I had it in overdrive). I was going up a hill at the time, but for the rest of the drive (up and downhill) the car would shift fine to first, and second, but wouldn’t go into third. I didn’t try pushing it too far into the red, although I tried drive and overdrive, but it was really strange because that’s never happened before. I’ve driven it a few times since, and it’s been fine. For the record, I’m quite sure I’ve never flushed the transmission fluid, but it may have been done before I got the car, or shortly afterward when I wasn’t paying as much attention to maintenance and repairs (and my mom was paying for the repairs!). Any ideas, or advice?

Thanks everyone for your expertise,


Possibly a bad 3rd clutch assy. What you really need to do is have a trans shop take a quick look. I would first hook up a scanner and drive it to see whether the computer is commanding the 2-3 shift. I would also check for any trouble codes.


Awesome, thanks for the reply. I guess I’ll have to take it in to a transmission shop. Do you think it could possibly be the modulator valve? I understand that’s a pretty easy and inexpensive repair.

I should add as well that I have 150,000 miles on the car. Thanks again!