Nissan Repair: Nissan Terrano Auto Transmission, nissan terrano, shaft speed

Question
Hi Von, I have a 1991 Diesel Terrano with intermittant auto problems - pulling away from lights, or roundabout it will drop into 1st gear.  I then have to stop and turn engine off and restart - usually this fixes the problem and the auto will change up OK. Sometimes I have to repeat the procedure. I have tried pulling over and running the stick down to Park and back, or even putting into R and backing a few metres, then into D and trying to go forward - this sometimes works.  Sometimes I have to adjust the stick in P (pull it toward me) when stopped and the engine off before the key will can be released from the ignition....  is this related?   Cant think of anything else to add to help your diagnosis...   thanks for help - Roger

Answer
Roger,

The transmission is controlled by a computer, different than the one that runs the engine.  Basically, a shift control computer.  The transmission shifts by means of solenoids.  The computer controls these.  There is a governor that provides output shaft speed to the computer and with other readings such as speed and manifold pressure the computer shifts the transmission.  I would think it is either the computer itself or a solenoid that is hanging.  If you have not changed the transmission fluid as of late I would do this first.  If that does not solve the problem have the shop run the computer codes for the transmission and see if it is a solenoid or the computer itself.  Email me back and let me know...