I have a 1991 JDM Nissan Terrano (D21) with a TD27T and an auto. I'm in New Zealand and I'm not sure where exactly this model is offered besides Japan (in NZ we import JDM cars) but I imagine the autos all around the world are probably using the same slush box.
I just bought this truck and it has been going well except I recently drove it and it would not shift out of first, unless I moved the auto switch on the centre console from normal to hold. On the hold setting it would shift immediately into 2nd and was shifting between 2nd and 3rd no problem. I drove home and it started to improve in that I could let it shift into 3rd in hold mode and I could switch it back to normal without it kicking down, but would still kick down into a lower gear at the slightest touch of the throttle.
When I got home I parked it for about 30 mins and then drove it again, it was now driving and shifting normally.
Any ideas what could cause this? Fluid level is normal, fluid is a bit old but not terrible (just waiting for my mechanic to get his fluid flushing machine in). Seeing as switching it to hold makes it shift immediately I'm thinking it's not a mechanical transmission problem but more likely an issue with how it detects speed, when to shift or a problem with whatever rudimentary old sensors this transmission might have.
This is the first auto I've ever owned so really don't know where to start with troubleshooting, and also have no idea how these old mechanical autos work and struggling to find any resources on the net. Any suggestions on what to look at would be much appreciated.