Really? I wonder why? .... anyway, I clearly didn't read all of it then. The only reason we end up in 4wd on the road is 'cause it didn't come out automatically.
Okay, so we'll just reverse it a little to ensure it comes out before we hit the road then.
Thanks All
The reason not to use 4wd on a hard surface, is that there is no central diff, or torque converter on a Terrano, so while the left and right wheels can travel at different speeds via the diffs on their axles, the front and rear axles are driven at the same speed, and rely on slippage if one set of wheels need to travel faster/further than the other set, e.g a bend. 4WD in a dead straight and level line would be OK on a hard surface, but that is practically impossible. The problem is, on a hard surface, if you do not go in an exact straight line, then all the wheels start to twist against each other as the ones taking the outside of a curve travel further than the ones on the inside, plus the front travels further than the back, and the result is they start to try and twist the transmission until something has to give, hopefully one of the tyres slip, but it could be worse! On a slippery surface, the tyres slip easily to remove the lock up, and everything is happy.
How did you decide it had not come out of 4wd? basically, once you return the lever to 2WD, the front wheels are physically disconnected from the engine, so you have to be in 2wd once the lever is moved properly.
As far as I can think, there are 2 potential things that you may have picked up on:
One is the auto hubs did not disengage, as mentioned by the others, a short reverse usually does that, but since some are fitted with fixed or manual hubs, and the front axle does have a diff, driving with them still engaged would hardly notice to most people. Basically, because you are driving a short bit of transmission backwards, which is then geared up, rather than down, it will have a bit of an impact on your fuel consumption, and I also find the steering feels just a tad heavier.
The second is that you were looking at the light on the dash board, which is controlled by a simple push switch somewhere on the side of the transfer box, and by pure mechanics get pressed when the lever is moved to 4wd. Maybe it is a bit sticky, and took it's time to pop back out when you returned the lever.