I thought I would let people know about my 4WD issue and how i fixed it.
I needed a wheel bearing replacing. I ordered a NON nissan wheel bearing to get fitted. I had my mechanic change it for me, which he did. However after fitting, he took it for a test drive and my dash lit up like a christmas tree. So the lights that came on, were abs, vdc and 4wd. So the van had no abs and was only running in rwd mode (i checked on his gravel path). So upon further inspection, it turn out to be the ABS magnectic ring on the wheel bearing was sitting too far away from the ABS sensor. Comparing it to the other side with the nissan bearing in, the nissan bearing ABS magnetic sensor was sitting about 1mm ish away from the ABS sensor. The aftermarket NON nissan bearing i had just replaced had its ABS magnetic ring sitting about 5-6mm away from the ABS sensor. We had no reason to believe that the ABS sensor had failed as it was left in the hub when replacing the bearing as quite often ABS sensors get stuck in the hub and brake when you try to remove them. So i got a proper NISSAN wheel bearing and swapped that out for the the aftermarket. So after fitting the NISSAN wheel bearing, it was taken for a test drive. All the ABS and VDC lights went out on the dash and i tested the ABS and the was working fine again but the 4WD light remains on. If I went to select 4WD AUTO or LOCK the all the lights would come back up on the dash. You turn the car of and then on again, and the ABS and VDC lights would go out again and the ABS working fine again but the 4WD light would remain. So if i left the 4WD selection alone all was fine. So i was convinced it just needed the 4WD codes clearing from the ECU. I had a cheapo code reader, which only read engine codes on Elgrand. My mechanic with both his fancy diagnostics machines could not clear the code (however somehow one of his units could read a code, a C1118 i seem to remember, but could not clear it). I went to another garage and still no luck on another 2 diagnostic units. I was about to give up and go to Nissan to get it cleared and wallet reemed out, then tried a local chap round the corner from where i live who specialises in auto boxes. He had 3 different Diagnositic Units he could try. First one no luck. The 2nd one wasnt looking hopeful. It picked up it was a nissan elgrand and we went to manually select the 4wd system, but nothing came up. Then he set the unit into a full system auto search mode or something like that.....and bobs ya uncle.....there was the 4wd error code. Cleared that. Turned car off and on again and the 4wd was working again as it was before. It been fine now for a good couple of months now.
So, i made a not of the unit he used and its called an "AUTOBOSE V30" and i think his was the "ELITE" version.
If you're down in the somerset area and have this problem his garage is called... IC AUTOMATICS LTD and hes located in High Littleton not too bar from bath or bristol.