Hi Briskoda members,

 

I've been looking for a solution for the following question for a while now without any luck so i turn to you for help. 

 

I'm trying to develop a small home-grown alarm system for my Octavia Combi 2010 that will be active only when the central lock is active. My problem, I know very little about car electronics and have no idea where to start. I could ofcourse run down to my local auto repair shop, but i'd much rather learn how to do this.

 

Preferrably there are 12V wires that I can connect to in the fusebox that only provides 12V if the central locking is active. That would allow me to connect the system directly to those and voila, I would be set. 

 

So, are there these magical 12V wires only powered when the central lock is active and if not, do you have any ideas on how I can connect my system?

 

Any help will be greatly appreciated - and sorry for any typos, etc...  :peek:

 

Br.

Jakob

Hi Mike,

 

Thanks for the reply!

 

Very interesting if that's an option!

 

Do you know how to connect to the BCM module and whether it will supply power only when the central locking is activated?

 

- Jakob

There aren't 12v supplies for things like this these days. The door and a control unit that is networked to the body control module.

Meaning that I would need to use one of the wires from the body control module to the individual door motors (or whatever is controlling the actual locking mechanism) to detect when it locks/unlocks?

 

It would be much better if there were an standardized approach - like the BCM module maybe?

You should look at the wiring diagrams for your car, they can be accessed for a small fee from Skoda: https://erwin.skoda-auto.cz/erwin/showHome.do

 

The only sensible place I can think of is the alarm LED on the drivers door but if you don't have a factory alarm it may not be fitted.

 

If you tap into the lock/unlock solenoids, you might have false activations if you have anti-hijack enabled (lock doors above ~5mph).

 

You might need to do something clever like doors locked and key removed from the ignition barrel. This will mean you'll need to run wires to the doors and ignition switch to detect these conditions.

 

Alternatively, you might be able to use a CAN bus tap to see when the lock/unlock events are received and trigger from that. This will mean you'll need to decode the CAN messages and find the right ones.

I'm not sure what you think you're doing, but most central locking systems only have current flowing whilst the doors are (un)locking, rather than at all times when the car is locked.

On second thought, you are right... Somethings wrong here.. 

If I connect it to the central locking mechanism, any thief can brake a window and just open the door from the inside which I suppose will unlock the door causing the alarm to be switched off. :-)

Perhaps I'll have a look at the drawings anyway, maybe that'll bring up some good ideas.

 

Thanks guys!

So your car doesn't have an alarm as standard? Is that a market limitation?

Cars in DK are expensive as ..., so most cars are pretty stripped down for any extra equipment -> No alarm.

 

Just tried the central-lock and you'r right - it doesn't open from the inside, so that's good news.

 

If the BCM is in charge of sending these events, then i guess it should be possible to wire a new controller to the BCM and tell the BCM (via the canbus) to send the central locking event to the new controller as well. Do you know if that is possible somehow?

Bugger. I hoped that there would be some sort of generic way of adding something to the central locking mechanism.

 

Ok, I'll have to investigate further with my local skoda shop then.

 

Thanks.

You could retrofit a factory alarm, do you have remote keys?

 

Otherwise, there are 3rd party solutions designed for CAN bus cars, for instance this: http://www.ampire.de/CAN3901V.htm?shop=ampire&SessionId=&a=article&ProdNr=CAN3901V&t=2899&c=11388&p=11388

The idea was to make it a DIY project, not to buy a third party solution.

A DIY solution can be much more fun to create!

 

It's just that given how modern cars work, you'll need some in detail knowledge about how both the cars electronics work and CAN bus. I'm not saying it's impossible, but probably very hard... Don't let me put you off creating your own system, but if you want something easier to install I'd check those pins exist on your BCM and consider adding a factory alarm to start.

 

The siren and internal sensors are cheap enough.

http://www.ebay.co.uk/itm/322176621076

http://www.ebay.co.uk/itm/121905272132

 

Plenty of info here including some of the wiring diagram:

http://skoda-ural.ru/repair/remont-zamena-sireny-shtatnoi-signalizatsii-na-a-m-skoda-octavia-a5-fl

 

This post also lists the BCM pinout:

http://www.briskoda.net/forums/topic/346789-cecm-pinout/?p=4186021

 

Looks like the sensor deactivation switch is between T52aa/36 and T52ab/37.

The LIN bus for the alarm siren and internal sensors is on T52ab/36.

Not sure where the alarm LED on the drivers door connects to - I can find out if needed.