Hi there, these Micras had problems with the lock/latch harness separating at the loom that runs from the body to the rear hatch.
This is likely where your problem stems from. You will obviously need the hatch open to easily access the harness and remove the grommet and loom covering it.
Thanks for your info I have had a look at this wiring and cannot see any obvious fault. is there a connection near the roof rails that I have not found? Meanwhile the weather has cooled down and my actions (as you suggest) appear to have worked is there any history with the weather known so I can calm my fiance whose car it is!!?
I followed all your suggestions as it confirmed a diagnosis that I made on my own car a year or two back. My nissan problem re-occurred a few days later when the weather heated up again so I triple checked the wiring again stripping out all the trim to get at it (becoming quite an expert at trim work!!) but found no sign of external damage. I then removed all the catches and switches from the tailgate and refitted very carefully with no change. Being somewhat pressured by my other half I stripped it again this time when I reconnected the microswitch that operates the tailgate from outside it opened the TG so I stuck the multi meter on the switch and got a 5k ohm measurement on the open switch and zero when pressed as it should so the problem turned out to be inside the microswitch which explained the weather related symptons. The local dealer had the switch in stock and exchanged a new on for a large number of beer tokens and the problem was fixed in 20 mins!! Hope this helps you in the future.
ps yes I did give a rating you helped set me on the right track. C