95 Voyager Output Sensor question

95 Voyager. 3.3L engine, 4 speed tranny, 192,000 miles.

Yesterday speedometer did't work, usually main culpurt is output speed sensor. Today speedometer is working again but tranny has very harsh downshift from 2nd to 1st when almost to a stop. Will a faulty output sensor also cause the harsh downshift??? It does shift fine in all other gears up amd down. Done the search with out finding same problem, sure I have read about it before but cannot find any like threads.

She also told me tonight that she had the tranny flushed about 4,000 miles ago a quick lube place which I know they didn't use the ATF+4 fluid and didn't change filter so I am going to change filter and flush system with correct fluid and removing the return cooler line to get rid of the improper fluid. Hopefully the crap fluid did not toast the tranny.

Thanks for input.

Changed the tranny filter and put the correct fluid in today, ATF+4. Still doing the harsh 2 to 1 downshift just before stopping. I am going to try output sensor next maybe the input also.

Changed the tranny filter and put the correct fluid in today, ATF+4. Still doing the harsh 2 to 1 downshift just before stopping. I am going to try output sensor next maybe the input also.

Changed output and input sensors, still had intermitent harsh downshift's. The vehicle has been driven now for several days and the downshift problem has seemed to decease but the speedometer has again quit working and rpm's jumped. Vehicle was stopped and engine shut off for couple minutes, started and all is working properly again.

If speedo quits again I will try changing TCM from a 93 on it too see if that helps if NOT I will start looking for a wiring fault. THinking it could be the 3 splice wiring fault that has been talekd about but never has been posted where it is located. If anyone knows where it is located please post.

Thanks

Far far from even a tranny expert wanna be but, a few fixes for harsh shifting I read about besides what you've already done:

> Get the TCM reprogramed ("flashed")
> Disconnect the battery for a few minutes. This will force the TCM to "relearn" shifting patterns.
> Change the fluid to the AMSOIL ATF4 equivelant.