Xantia Central locking fault

[Mandrake]

Hi All,

The central locking on my Dad's 1994 Xantia SX has just started acting up recently - sometimes when locking the doors it will unlock again half a second later - the same behavior you would normally get if the opposite front door was left open while trying to lock, except the other door is closed properly.

I've seen it happen in front of me for the first time today - and I re-closed both doors and it was still doing it, a dozen times, then a bit later it started working again - clearly an intermittent fault.

More worrying is that apparently it sometimes unlocks the doors some time after leaving the car "locked", thus leaving the car wide open to theft of contents...

I have to look at it in a couple of days, so can anybody give me some pointers ? I'm presuming that the fault can only be in the front doors (or the control system) as the rear doors don't have a sensor to tell if they're locked at all ? (They're just a passive slave)

When a front door is open the central locking will unlock after you try locking, so the switch/sensor that detects if the doors are open or not (in the lock mechanism, not the interior light switch) seems like the logical first place to look - except I don't know which door it might be.

Anyone had a similar problem and tracked it down ? In the meantime I've had to remove the central locking fuse to stop it from unlocking itself randomly...

Regards,
Simon

[kevino]

Hi I have this same problem I think I have found the fault on my car but haven't done anything about it as of yet.
I have tracked the fault to the front passenger door, when the fault happens put the key in the passenger door lock and rotate it to the locked position, whilst doing this, press the button on the remote to lock the doors it seems to work and stay locked. I am going to replace the central locking sensor on the passenger door to see if that cures it. If you find any less expensive quick fix let me know.

Cheers Kev o

[DickieG]

I've had this problem on a couple of Xantia's now, each time its been down to a poor electric connection between the plug and socket of the lock on the front nearside/passenger door. A cleanup sorted it out.

[uncle buck]

I had a similar problem on my ZX about a year or so ago

At first the drivers door was just occasionally showing as being open on the door open dash display thingy.....but soon after the opening & closing thing started....I removed the door lock mechanism & found the fault to be the micro switch on the mechanism...it was covered in a thick paste of grease & muck which must have built up over the years...a good clean & the problem was sorted

[kevino]

thanks for the advice, I will tackle this annoying problem as soon as my bad back clears up.

Cheers kev o

[xantia_v6]

To identify which lock is faulty, lock and unlock the car manually from each door, using the key or the lock button on the door.

When locked manually using the FAULTY lock, the other locks will never spring back open.

[jonnydrumm1967]

A similar thing has been happening in a 95 Xantia estate I'm using.

Using the key to unlock the car (the remote's goosed)the locks would go haywire,locking and unlocking up to ten times. It would also,lf left unlocked,lock itself minutes later! trapping the keys inside...
looking to take fuse21 out I discovered it was already missing...! So I disabled the ECU that lives next to the handbrake.Problem solved for now until I find the time to sort it properly.

[Mandrake]

To identify which lock is faulty, lock and unlock the car manually from each door, using the key or the lock button on the door.

When locked manually using the FAULTY lock, the other locks will never spring back open.

Hi - unfortunately the barrel in the passengers door is now faulty (I've had it out and the inner sliding part that slides with the key insertion is split) so it can't be locked/unlocked from the key on that side... but this problem has existed longer than the faulty lock.

If I lock and unlock using the buttons inside the door, the problem happens from BOTH sides - making me think its probably a fault with the microswitch or the wiring rather than the lock mechanism. (faulty lock barrel excepted)

Thanks all, I'll have a look at the switch and cable on the left front door and see what I find.

Regards,
Simon

[xantia_v6]

If I lock and unlock using the buttons inside the door, the problem happens from BOTH sides

You should also try the rear doors and boot lock, as they could be the problem.

[Mandrake]

If I lock and unlock using the buttons inside the door, the problem happens from BOTH sides

You should also try the rear doors and boot lock, as they could be the problem.

Don't quite follow this - the rear doors and boot are all just 'slave' doors - unlocking the rear doors doesn't operate the central locking, nor does leaving a rear door open prevent the central locking from working normally...

Unfortunately bad weather prevented me looking at it today, so it will have to wait until next weekend now.

Regards,
Simon

[xantia_v6]

You should also try the rear doors and boot lock, as they could be the problem.

Don't quite follow this - the rear doors and boot are all just 'slave' doors - unlocking the rear doors doesn't operate the central locking, nor does leaving a rear door open prevent the central locking from working normally...

You seem to be right. Failing memory on my part... sorry

[seedy]

I know this thread started a while ago, but the problem might still arise for other users...

I had the ‘spontaneous central locking problem’. I would drive along to the accompaniment of the doors locking and unlocking repeatedly. People at traffic lights would wonder what the noise was. I’d arrive at a destination and find the car locked – had to insert ignition key, turn on ignition, lower window, turn off ignition, remove key, use key in external lock, open door (pretty smartly), insert key, turn on ignition, raise window, etc…

(Yes it might have been possible to close the window with the door open and no ignition).

Sometimes you needed two hands, one to unlock and the other to open the door – if you used the same hand, it’d be locked again before you got to the handle. I’d leave it locked overnight and come back to it unlocked. I daren’t leave the keys inside and close the door. It was embarrassing.

This went on for a couple of months. Then the clutch cable snapped. I disconnected the battery whilst I did some work, reconnected and – presto. The locking works as it should. Now where did I save the radio code...

[seedy]

So here we are a few years on and I have another Xantia and it has a locking problem. I say to people, 'I have had a similar problem before but I can't remember how I fixed it. Perhaps I can find something on the Forum'. I did find the answer - in my own post from 2009. And it reminded me just how bad the earlier problem was. I love these cars, but then you have to.

[Mandrake]

Even worse, sometimes I search for something Citroen related on Google only to find the top matches on Google are links to threads on this forum, often threads I've started or posted in, that I had completely forgotten about, and that the answer to my question is sometimes in one of my own forgotten posts!

At least Google is doing a good job of finding stuff...

[myglaren]

At least Google is doing a good job of finding stuff...

It is, no question.

Firefox has for a while now defaulted to Yahoo! - possibly as my ISP is BT(Yahoo!) in the navbar.
It couldn't find it's own arse with both hands and a torch.
Fortunately Google is default in the search bar.