Honda Repair: 91 Accord EX wagon transmission, transmission control unit, accord wagon

Question
The sport overdrive on my '91 Accord EX wagon will come on and stay on without warning which is locking the transmission in a single gear (presently 3rd gear).  When it happens, I can hear a clicking sound underneath the front passenger floor.  It almost sounds as if a switch is engaging and causing the transmission to stick in one gear.  Is this a simple matter of replacing a switch or does it indicate a more serious issue with the transmission?

Answer
That year is bad about the transmission control unit going bad.  I priced one this week at about $1000.  If you are lucky enough to find one used, you will need one from a 90-91 Accord wagon and must be a 90-91 Accord wagon.  You will want to see if there are any codes in the computer before you go replacing anything.