Toyota Repair: transmission problem, 1991 toyota camry, electric solenoids

Question
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Followup To
Question -
Hi Ted,
    I have a 1991 toyota camry 4 cylinder with 140,000 miles.  The previous owner replaced the tranmssion with a used one from Japan.  The transmission skips 1 gear; shifts ok from 0-15mph then goes flat (2nd gear skips) and shifts to 3rd gear.  The O/D light flashes when this problem occurs and the O/D does not not work.  I get about 20 mpg combined city and hwy now.  If I replace the transmission with a rebuilt one will my gas mileage improve significantly?  Also is it a good idea to purchase a  used transmission with low mileage from one of those garages which import them from Japan?
Thanks in advance!
Stan

Ted you did NOT answer my questions.  I did bring my car to an transmission repair shop  AAMCO.  They could not diagnose the problem but recommended replacement of the transmission.   There were NO diagnosis codes displayed on the handheld computer.  Again, if I replace the tranmssion with a rebuilt one will my gas mileage improve signficantly?  Also is it a good idea to purchase a used transmission with low mileage from one of those places that import transmissions from Japan?  
Again, THANKS in advance.

STAN


Answer -
You could have the transmission computer checked for any codes, usually when the o/d light flashes there is a control problem with one of the solenoids, have this checked first, there may not be a mechanical problem with the transmission but rather an electronic control problem, the shift points are set by the computer and the actual shifting is commanded by electric solenoids, I recommend that you have the toyota dealer diagnose what the problem is and go from there.

Answer
With a properly functioning transmission the mileage should improve, in most cases there is no problem using a low mileage transmission from japan, make sure they give you some guarantee that it will work after installation and get it in writing, the guarantee varies from a few months to a year depending where you buy it, most of these places offer the guarantee on the part only and do not cover labor costs should there be a problem.