Central locking locks rear doors, and immediately unlocks

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Jugostran
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My Cars: 1989 Cimos-Citroën BX 16 TRS

Central locking locks rear doors, and immediately unlocks

Post by Jugostran »

Hey, so, I've been having this problem since I got my '89 16 TRS. When I lock the car from the driver's side, the rear doors lock, but immediately unlock again. Then I have to unlock the front doors, and relock in order to get all doors to lock. After doing this, the central locking works perfectly. Well, perfectly until I go for a drive. The issue only seems to occur if the car has been driven.
Any help would be appreciated greatly.
(PS: the car has no remote lock/unlock)

Kaapelimies
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Re: Central locking locks rear doors, and immediately unlocks

Post by Kaapelimies »

The problem might be the microswitch in the lock itself or a broken cable at the hinges. Do you have the "doors open" led-panel next to the ashtray and does it show that all doors are closed?
BX 4x4 estate, several BX Van's and some more normal estates in Finland.

Jugostran
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Re: Central locking locks rear doors, and immediately unlocks

Post by Jugostran »

The cable probably isn't broken since the locks do work after the first attempt. Also, the doors open panel is partially broken due to burnt bulbs (don't know how to fix). But those lamps that do work indicate all doors as closed.

Kaapelimies
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Re: Central locking locks rear doors, and immediately unlocks

Post by Kaapelimies »

Yes. They work like that because the controller _thinks_ one door is open. The second time you lock is override mode, so your ALL doors won't be open. This mode is missing from the C5 and it sucks. Just check the cables and microswitches from the locks (after fixing the doors open panel, pull it out and change the bulbs, if they still don't light up this is the proof of broken switces or cabling). Sometimes, the controller box can be faulty (next to the handbrake lever) but this is not so common.
BX 4x4 estate, several BX Van's and some more normal estates in Finland.

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white exec
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Re: Central locking locks rear doors, and immediately unlocks

Post by white exec »

That may not be the case.
Have just checked on ours, and leaving a rear door open does not prevent normal operation of central locking from the driver's door. (You can't leave the driver's door open and try to lock it - the key will not turn in the lock.)

IIRC the doors open indicator is just lots of 1.2w capless (T5) bulbs.

The circuit diagram for central locking is in Haynes, Fig.13.76 circuit IX (cars from 1987). Haynes editions vary.
There does not appear to be a connection between the four door-open switches and the central locking system, so back to the locks themselves.

Just possible the original PLIP (#91) remote receiver is misbehaving, even if you're not using it.
It can simply be unplugged, and should leave central locking working from the driver's door.
Chris

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Vanny
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Re: Central locking locks rear doors, and immediately unlocks

Post by Vanny »

This happens on my car all the time. One or more of the motors jams and probably goes over current,asking the controller think it didn't lock, and unlocks again.

Solution was initially a replacement driver door actuator, but as the rest of the lock have got old, same issue reappeared. Lubricating the mechanism and using the car more works.

Jugostran
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My Cars: 1989 Cimos-Citroën BX 16 TRS

Re: Central locking locks rear doors, and immediately unlocks

Post by Jugostran »

Vanny wrote:
Fri Sep 24, 2021 7:14 pm
This happens on my car all the time. One or more of the motors jams and probably goes over current,asking the controller think it didn't lock, and unlocks again.

Solution was initially a replacement driver door actuator, but as the rest of the lock have got old, same issue reappeared. Lubricating the mechanism and using the car more works.
I have some lithium grease ready. What exactly do I need to lubricate? Thanks everyone for all the helpful suggestions by the way!

Jugostran
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Re: Central locking locks rear doors, and immediately unlocks

Post by Jugostran »

white exec wrote:
Fri Sep 24, 2021 5:55 pm
That may not be the case.
Have just checked on ours, and leaving a rear door open does not prevent normal operation of central locking from the driver's door. (You can't leave the driver's door open and try to lock it - the key will not turn in the lock.)

IIRC the doors open indicator is just lots of 1.2w capless (T5) bulbs.

The circuit diagram for central locking is in Haynes, Fig.13.76 circuit IX (cars from 1987). Haynes editions vary.
There does not appear to be a connection between the four door-open switches and the central locking system, so back to the locks themselves.

Just possible the original PLIP (#91) remote receiver is misbehaving, even if you're not using it.
It can simply be unplugged, and should leave central locking working from the driver's door.
Thanks for the advice! Now, how do I access the door open panel? Also, are the bulbs easy to replace, and if so, what sort of replacement should I get?

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white exec
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x 54

Re: Central locking locks rear doors, and immediately unlocks

Post by white exec »

Like the ashtray and coin holder, the d.o.display comes out forwards. It's on four springy plastic lugs.
If you slide the ashtray and coin holder out (just open, and pull), you can put your hand behind the display, and just push it out.

The bulbs are T05 (T5) capless, W1.5W 12v (or 12-14v) 1.2W. Motor factors will have them, and you can usually find a box of 10.
They slot into the black bulb holders, which come out of the panel by rotating them anti-clockwise - use a small pair of pliers, as they're likely to be stiff with age. The bulbs pull straight out of the holders, but again can be stiff. You can grip the bulb glass (for removal and inserion) with a short length of plastic/rubber tubing, to get a safe grip.
Chris

Jugostran
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Posts: 9
Joined: Fri Sep 10, 2021 6:22 pm
Location: Subotica
My Cars: 1989 Cimos-Citroën BX 16 TRS

Re: Central locking locks rear doors, and immediately unlocks

Post by Jugostran »

white exec wrote:
Sat Sep 25, 2021 7:16 am
Like the ashtray and coin holder, the d.o.display comes out forwards. It's on four springy plastic lugs.
If you slide the ashtray and coin holder out (just open, and pull), you can put your hand behind the display, and just push it out.

The bulbs are T05 (T5) capless, W1.5W 12v (or 12-14v) 1.2W. Motor factors will have them, and you can usually find a box of 10.
They slot into the black bulb holders, which come out of the panel by rotating them anti-clockwise - use a small pair of pliers, as they're likely to be stiff with age. The bulbs pull straight out of the holders, but again can be stiff. You can grip the bulb glass (for removal and inserion) with a short length of plastic/rubber tubing, to get a safe grip.
Thanks for the assistance! Sounds quite simple. I'll let you know how it goes!

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Vanny
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Re: Central locking locks rear doors, and immediately unlocks

Post by Vanny »

I lubricate the mechanicals of the latch and the associated rods. Not tried lubing the motor its self yet.