Nissan Repair: transmission shifting funny, automatic overdrive transmission, lockup torque converter

Question
I have a 1994 altima w/ auto trans it does not slip but will not shift into overdrive correctly it does hesitate to shift sometimes what could be the problem shift soleniod tourqe converter ? I am a fair mechanic I know more about domestic cars than foreign.

Answer
Mark,

The automatic overdrive transmission uses a couple of things to allow it to shift into overdrive and to have the lockup torque converter to apply.  First, operating temperature has to be reached.  If the temperature switch is screwed up it will not allow the shift or lockup.  Second, there is a vacuum switch that lets the computer know there is not a load and to allow the overdrive shift and the torque converter to lock up.  Get a factory manual if possible since it has everything.  Otherwise, get a Haynes or Chilton to show the location of the switch and such.