Locking Issues

[DaveyP]

2002 V70 T5

I've looked through various threads about central locking on here. Sounds like it might not be the most dependable system in the world?
Anyway, the issue with mine is that it keeps re-locking it's self after I've unlocked it.

I've had cars in the past that would re-lock themselves if they had been unlocked and left untouched. Makes sense. But the Volvo will re-lock it's self unless I turn the key in the ignition.
No matter which doors I open. In fact, it even re-locks it's self with all the doors wide open unless I turn the key in the ignition. So far this has only presented a minor irritation, but the day is coming that I or my better half will lock the key in the car. We all know it is.

So, any ideas? Can the system be somehow reset? Could there be a faulty switch / sensor somewhere that I don't know about? The interior light comes on/off as expected, so I assume all the door switches work, although I can't say that I've actually tested these.

Any help appreciated.

[Dangerous Dave]

Found the same issue here:
https://www.volvo-forums.com/t37010-v40-relocking-itself.htm

Seems like it was a sticking fob "lock" button. Maybe worth taking the circuit board out of the fob and operating it without the fob shell to see if it still does it. After that maybe remove the battery and operate the door locks with the key to totally rule out the fob (easy stuff first).

Then maybe the door lock button inside the car by the window switches (as they can get quite cruddy)?

[DaveyP]

Nice one.

I'll try cleaning them all up.

Thanks

[DaveyP]

Nope, it still does it. Locks it's self even with doors open. It also sets the alarm. Sometimes it happens without me ever having locked it. For example, I drive it home, and it locks it's self while I'm unloading shopping or whatever. Boot open, doors open. Then the alarm goes off the next time I stick my head inside the car...

[LeeT5]

The alarm is a Thatcham approved unit, so it will always arm the alarm when it locks with key or the remote.

I would plug in VIDA or a diagnostics that can communicate with the Alarm control module. This would give you some idea as to what is at fault as there will almost certainly be a fault code or ten!

Top tip: If multiple codes are present across multiple modules, then clear faults first, then rescan after a short drive cycle (couple of mile). Then relock the car and unlock it and then scan.
It could be a short circuit in one of the door locks, hence it locks and rearms the alarm.

[DaveyP]

Fixed it.

Just posting for the record in case anyone reads this in the future.

Someone had, before my ownership, mucked about with the wiring in the driver's door, shorting two wires together. I rectified this, and the locking went dead. Could lock/unlock the driver's door with the key, but nothing else.
Assumed it had been butchered rather than replacing a dodgy lock assembly.
Got a second hand one, swapped it, all's well.

[MoleT-5R]

Fixed it.

Just posting for the record in case anyone reads this in the future.

Someone had, before my ownership, mucked about with the wiring in the driver's door, shorting two wires together. I rectified this, and the locking went dead. Could lock/unlock the driver's door with the key, but nothing else.
Assumed it had been butchered rather than replacing a dodgy lock assembly.
Got a second hand one, swapped it, all's well.

Well done there and thanks for posting the solution, nothing worst than something that just doesn't work as it should.