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Hi

I've owned the van for a month now, and covered about 2k miles.. through this time the central locking has been flawless. It is operated by the 'Sigma' alarm remote fob , for unlocking and locking.

Now, however, the blasted thing doesn't attempt to lock!

The alarm still sets, the indicator alert still happens, all as normal, but the locking doesn't attempt to fire.

However - if I then manually lock all the doors - then when I come back to it I press the sigma fob button to disarm, it all unlocks beautifully!

If I haven't manually locked the doors, the sigma doesn't attempt to unlock them, there's no 'thunk' of it operating.

so.. all that appears to not be being attempted is the 'Lock' process.

Any ideas?! I don't even know where the alarm is situated unfortunately, it was on the van when I got it.

I have checked all the fuses - all fine, and like I say the unlock works fine.

all suggestions appreciated!

Thanks

Ben
 

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You will need to find the alarm to see if it controls the locking directly or if goes via a dedicated locking relay. There may be individual fuses on the alarm outputs or it may be a faulty locking relay (if fitted).
 

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Do you know which sigma system you've got?

I've got a sigma M30 in my van, and I can say for definite that it does not control the central locking directly. There are negative outputs from the control box which will then feed to relays or central locking controller. I'll send you a PM with location of box.
 

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That's a coincidence. I had almost exactly the same problem except it would lock but not unlock (not great after windsurfing for 2.5hours in January).

My alarm was the Sigma M2 with an AC29 central locking module.

The central locking module contains a double relay (wiring diagrams available online) that was earthed on one side or the other to fire the solenoid. The AC29 wasn't difficult to test and was found to be working fine. (I have it still if you need a replacement)

The alarm module would open the wire to earth on the lock side but not the unlock side. Because it was the alarm module itself, I didn't even try to fix it. In the end I picked up a Toad Ai606 for just over £100 (which has the C/L relays in the box already) and spent a saturday afternoon with the fusebox out.

All works now. The toad is a better alarm with more features.

Hope this helps.
 
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