Update #2

Its fixed!!!

How?

Self healing car. We finally had a warm day and it just started working on its own.

Either the lock was frozen or maybe the grease being cold got sticky and the mechanism would not function. Not sure, but it had to do with sub freezing temps.

 

Actually Land Rovers do that, perhaps too often it seems - fix themselves and then you are waiting for it to happen again.

If the problem reappears, there is a splice hidden within a wiring bundle under the door sill, sometimes the passenger side and sometime the drivers side, that consists of three about 22 gauge conductors and one of those telephone squeeze type wire joiner things.

Water gets inside the spice and the resulting corrosion reduces conductivity. These wires send signal to the door lock to operate.

I wondered if you tried the mechanical door mechanism just to confirm that it does work or not. If you do try it, make certain you have either a window down or one of the other doors open.

... and thanks for the update - it is appreciated.

 

I think this issue was purely mechanical in nature.

At no time did the door lose power. Using either the key-less or the button on the dash the door lock would make a sound and also the lever would move in/out on pushing the unlock/lock button.

It was as if the mechanism that actually locks the door was getting power but sticking.

I don't like working in freezing temps so I left it alone till it warmed up.

 

I do not do much either re "fixing" on my 3 in the winter; too much stuff snaps rather than releases; hence I delay most of my fooling around stuff as best I can.

The location and operation of the single mechanical door lock is explained under the locking section of the owners manual. It is a good thing to have practised before hand as if the battery is dead, the mechanical lock is the only simple way of getting in. The alternatives usually require breaking something expensive.

Also the mechanical lock can "freeze up" with lack of use; hence once a year at least, I usually cycle mine - that is try it out just to see if it is still working; also that way I renew my unlocking skills and hence nothing breaks as that can be a problem as well.

 

That sounds like a good idea, as I've never tried the manual key method.

What kind of lube should I use on the door mechanism? Dry stuff, or like WD 40?

 

Whenever I lubricate locks, I always use powered graphite. I have a little squeeze tube of the stuff. I just stick the nozzle into the lock slot and squeeze a couple of puffs in there; also I apply some to the key blade and then insert the blade a few times. Other than that, you would have to pull off the door card, and that you do not want to do unless there really is a problem.

I regard WD40 as more of a cleaner - that is it washes away stuff; that can be good or bad depending upon what you use it for.

WD40 as a good cleaner for the block valve O rings as they need stuff, usually the broken up desiccant powder, to be washed away. Lock mechanisms on the other hand, usually need lubrication rather than cleaning and with something that does not attract dirt or that dirt does not soak into.

 

Update.
Well the sticky door lock is back. I had my LR3 at a body shop and they pulled the door cover and lubed it. It did work for about 2 weeks and now that its cold its sticking again. Locks maybe 50 percent of the time.

It has a plastic sleeved cable that connects to the locking mechanism. Just like a 10 speed bicycle hand brake. I probably will have to buy the part and change it out.