1993 Toyota Camry

Transmission problem
1993 Toyota Camry 4 cyl Front Wheel Drive Automatic 180000 miles

I have a Haynes manual #92006 for this car, but can't find enough info to determine problem. All forward gears / speeds good with NO slipping, AT fluid levels were down slightly & were re-filled.
Since the on-set of problem was sudden, I suspected reverse solenoid in transmission is defective or not getting a signal to acctuate-- anyway to test?
Car has a tach & I read the tach speed @ 1200 rpm running- cold- that dropped to 1000 when (D) drive was engaged-- but tach does the same thing-- 1200 drops to 1000 when (R) reverse is engaged.
Is this a result of the reverse solenoid engaging or is the ECM or CPU reducing the rpm?
Is the park / neutral switch in the electrical circuit for the reverse solenoid? Car was towed with-in the last 60 days, ignition coil, & the wrecker operator was " rough" when he manually tripped the shift lock - I witnessed, but the car didn't show any immediate effects. Could this have an effect? The shift / lock control switch is still operating, car will start in park & neutral only.
January 27, 2009.

With 180000 miles on it when was the last time the transmission had been serviced { fluid changed and the filter changed.} Was this doing this since it was towed or had this happened even a little before it was towed? How does the transmission fluid smell. Does it smell with a burnt smell? If so then I would have the fluid changed and filter. This might not stop the problem if the transmission hasd internal problems but I would start with the fluid changed.

Jan 27, 2009.
I do basic repairs & maintenance on my cars, family & friends, including oil w/ filter, ATF & filter, gas filter, fuel pump, brakes etc anything top or bottom that doesn't require pulling heads or dropping bottom (oil) pan & I have replaced a transmission solenoid. This is my wife's car & unfortunently she doesn't keep up with the info I give her concerning the mileage & work done @ the time of repair--- she will sometimes take car elsewhere for maintenance without telling me but thanks for the response & I will replace the ATF & filter to see what difference, if any, this will make. Any other thoughts or suggestions would be appreciated. LARRY MO

Jan 27, 2009.
When you put it in reverse can you feel anything. Even the slightest trying to move back or a burnt smell on the dipstick. If it does then I would think about the changing of the fluid. Check the shift linkage. With it being towed a linkage could be off.

Jan 27, 2009.