A blinking O/D lamp is the transmission equivalent of the "check engine" lamp -- it means the tranny computer is unhappy about something.
See
http://www.camrystuff.com/manuals/Gen3/ax1.pdf , starting at the middle of page 44 for instructions on how to get the diagnostic code from the computer (use an unbent paperclip to jumper the terminals on the DLC). Once you have the code, c'mon back and we'll take it from there (there's also a pretty decent troubleshooting section in the abovementioned FSM chapter if you want to troubleshoot after you get the code).