Ok, as you know. I posted about my overdrive not working, well that is not the worst of it. I went to the store a few min. ago and when I was headed home my car was stuck in 2nd gear. it would not down shift or advance to 3rd. Has anyone had this happen to them? I need some help. thanks.

Yes, it could be one of about four things. Input speed sensor, output speed sensor, solenoid pack or internal transmission problem.

First off...
The input speed sensor reads the speed of the input shaft in the transmission. The output speed sensor reads the output speed. Basically says what speed is the engine going, and what speed is the car going. The input speed sensor is closest to the engine, the output is closest to the wheel. The solenoid pack opens and closes different valves based on transmission fluid pressure, throttle position, rpm and other stuff. The solenoid pack is the big box below the transmission cooler lines.

Next... Does your speedometer work?
If it does work you can eliminate that as a possible cause.
If your speedometer DOES NOT work, there's a very good chance that it's the output speed sensor. It's like $20-$30 but you can only get it at the dealership.

The input and output speed sensors both give the same symptoms but only the output will affect speedometer reading.

Chances are it's either one of those sensors. It's cheap and you can put it in yourself. Both are located on the transmission. Pop the hood, find the transmission cooler lines. Directly below them is the input speed sensor. To the right of that is the ouput. They both look identical until you take them out. One has a tit on the end, the other does not. It requires a 1" socket and maybe a 3" extension.
The input speed sensor replacement may also require disconnecting the big plug that goes into the component below the transmission cooler lines. This is the solenoid pack. Some have a black cover to keep down on the ratcheting type noise of the solenoids and newer ones do not.
After removing and replacing the suspected bad sensor, remove the fuse labelled "Engine" or "Motor" in front of the battery for about 2 mins. Then put it back in and crank the car up, go for a drive and see how it does. Some places recomend replacing both at the same time. I did after my input speed sensor went out just because the other normally fails soon after.

If the problem still persists, Retrieve the codes or take it to a dealer. It could be the solenoid pack, or something in the transmission like the torque convertor, valve body or other related items. It's easy to replace the solenoid pack but it's expensive and shouldn't be replaced just for the heck of it.

Hope this helps,
Doug

Just a note. No need to post the same problem in more then one section.

as I was driving yesterday, my car got stuck in 2nd twice again.. this was AFTER I went to the dealership a couple years ago with the problem and got a new transmission and computer.

about the speedometer working... between about 60+ my speedometer sometimes likes to bounce up and down, I thought it was because I changed my gauge faces and took out the needles, but I was just wondering if the bouncing is actually the speedometer not working, anyone know?