to start off i have a 1999 s-series trailblazer 4x4 auto trans. so as i was getting on the freeway i laid the go pedal down more and my RPMs jumped like it downsifted then immediatly up shifted and on came the SES light. it ran fine but the light stayed on. when i got to wear i was going i disconnected the negative terminal for awhile then reconnected. light went off. truck ran fine all the way home. any clues? thanks!! and please let me know if you need more info.

Superpoo

 

Yup, that sounds wierd.
How many miles on it? Have you ever serviced the transmission?
I'd check the transmission oil.

 

I'd start by having the codes scanned before removing the battery terminal. The light means that a trouble code was stored and that something went wrong, requiring attention/repair. Autozone/Advanced/etc will do free powertrain code scans. Most of them require that your CEL (SES) light be on to tell you the code, but if you find yourself at one of these stores, have them scan it. If you come up with codes, post them here and we'll try to help in any way we can.