Nissan Repair: terrano td27 auto, shift into overdrive, vacuum switch

Question
Hi Von,  my Terrano TD27 auto suddenly wouldn't shift into overdrive, and the box stays in 3rd.  Next day it was ok again, but fault then returned.  Fault is there almost all the time now, but occasionally it will be ok even if only for a few minutes.  Torque converter locks ok in 3rd. Someone has suggested TPS on the injector pump or temp sensor (there are 2 of them)Vehicle is a Jap import, Parts are very rare in Australia. I am at my wits end. Please help.

Answer
Peter,

Check the overdrive button and the wires leading to it.  These have a tendency of shorting out intermittently.  Pull the button and wires and find the open.  That is the usual problem.  I say this since the torque converter locks up.  It it did not lock then I would say the vacuum switch that lets it know when to lock the converter and shift to overdrive.  It will not lock the torque converter or shift to forth gear until it is at operating temperature.