My central locking isnt working at all, in-fact I cant even open the passenger side doors... does anyone know what the main causes for failure and how to trouble shoot effectively to isolate the faulty bits?

Having similar problem,

Central locking works randomly, it locks each and every time, but unlocks every now and then.

Have tried all sorts of things, like changing receiver and sender, sorting out ground contacts, etc and none worked.

Any idea?


Thanks

Ziga

check that the power cable of the receiver is pluged in properly

I had the problem of the pin in the fuel flap lock hitting the edge of the hole and unlocking the car had to push fuel flap in to get it to lock right

the mechanism's on the doors attract the dirt and grime which cause them to stick. also the electric motors themselves the grease dries out in them. also the metal warps due to the stress of the mechanism sizeing up.

clean the whole mechanism on every door
split every central locking motor


grease everything! youll find that it will lock and unlock fine!

Will do, thanks!

I think the mechanics in the 405 doors and locks generally are prone to fail way too early!

If one of the locks i.e. gets resistance (i.e. the push/pull knobs inside), it will unlock randomly, or 1-2-3 seconds after you lock with the master...
This has been an issue in all the 405's i've seen. Sad to say, i wish our cars were a little bit more like i.e. german cars in this area..