Doors refuse to stay locked

I've just brought my 2006 Eton Mk6 Transit to the house from winter strorage, all seemed fine, both batteries fully charged and no other obvious problems until I came to lock the cab using the remote fob. The doors lock and then about a second later they unlock, I managed to get it to lock eventually and thought I'd try unlocking and locking again, with the same thing happening i.e. lock then unlock. I tried using the key with the same result. I then opened and closed all doors including the habitation door and gave it a good slam and it locked. 

Are there central locking/immobilisor sensors on the habitation door, could this be the problem?

I'm at a loss as I have no electrical knowledge and just wondered if anyone had come across anything similar or has any suggestions before I go to the expense of involving an auto electrician?

Thaanks in advance.

Marko

On my Nuevo there are indeed sensors on the habitation door.

I clean them with isopropyl on a regular basis, otherwise the habitation door won’t lock.

Terry

I would guess that's the answer.

If all the doors are not completely closed the remote door lock pings open again. Can't think of anything else.

When I had those sensors (which are better than the frequently splitting cable at the bottom of the door!) I gave them a squirt of WD40 after cleaning. It did appear to delay the corrosion, but as Terry says, regular cleaning is the answer.

Thank you so much Terry and Gromit, I've just cleaned the upper and lower locking bars and the associated brackets with isopropyl and all seems well, I'm assuming that when you say sensors you mean where the contact is made on the bars and brackets?

No.

The "sensors" are not actually sensors, it's just a group of three (I think, from memory) electrical contacts situated near the top of the opening side of the door. One half on the door frame, and the other on the door itself. One half is a set of sprung plungers, and the other set is contacts for the plungers to press against to complete the electrical circuitry.

They get a bit grubby and corroded over time and fail to make a good contact.

That means they will either not lock, not open, or both - and the problem can be intermittent as you have discovered.

They are quite obvious when you know where to look! 

Thanks Gromit, I'll have a look in the morning. Stop Press I've just had a look and the only possible points of contact are as I described, no plungers or anythiing like that and as I said cleaning the bracket and cylindrical bars seems to have solved the problem, I'll look again in daylight to make sure and post pictures if not sure. Thanks again.

No other contact points and all good so I'm happy except the toilet flush pump is not working but I can live with that until the next service.

Check the fuse on the toilet pump - and the fuse contacts is where the fuse fits into its holder. The fuse is located to the left of the cassette and can be seen if the cassette is removed.
I have a cable connection between the hab door and the body so no contacts problem. Header,if the hab door is not FULLY closed, is partially but not fully latched the locking does not work at all. I guess there is a Microswitch in one of the snap-over catches.

if you have a cylinder that is tight and reqs freeing up will make the others unlock as this cylinder is not going to the full lock position .if any of the inside levers is not returning fully will also make it unlock as it sounds like you have done a bit of lube (spray grease is best long term)

Thanks everyone, the doors lock fine now and the pump can wait.