92 Metro automatic won't shift

My 92 Metro with automatic will not shift on its own. I can manually run thru the gears so I figure the tx is ok. The thing is stuck in high. Does anybody know where the automatic transaxle module control is located? I hear its under the dash but thats pretty loose. Does anybody have a way to figure out what part(s) are bad??

Okay, first I'm. no expert. But I used to work on automatic transmissons. The first thing to do is check the fluid level and make sure it's still bright red and doesn't smell funny. By funny you'll know something is not right. If fluid level is ok and fluid isn't black when you wipe with a rag like you would checking engine oil, then it's the governor. If you can manually shift thru the gears fine, then that's your problem. The governor is stuck and doesn't allow the proper pressure required for the valve body to shift on it's own. Don't quote me but it also might be called a vehicle speed sensor on the Metro. It
is located on the trans not under the dash. Hope this helps.

thought the speed sensor was built into the speedometer on metros? the computer for the transmission is located under the dash above gas pedal, its another silver box like the main computer just a smaller size

Automatics have a separate speed sensor built into the tranny. There are a couple of solenoids in the transmission that do the shifting. I've heard it recommended that if it's shifting funny you can disconnect the wires going to the solenoids and if it shifts manually, the trans is okay, problem is in the control system. Sounds like that is what you have going on. Unplug everything going to the transmission and plug it back in. This will renew the connections and is a good idea for every connector in your car. Beyond that you're looking at a complicated troubleshooting procedure that will require a factory shop manual. Last automatic I owned was junked in 1977, so anything I say is hearsay.