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Modify central locking

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Rogge69

New Member
Hi!
Have got a wish to be able to lock and unlock (from driver's seat while driving) the sliding door separately from the other doors on a minibus and tried to figure out an appropriate way. Have got as far as the scematic shows but then came to a stop. My idea is to cut the original cables to the central locking actuator in the sliding door and allow the signal to go through a couple of changeover-relays instead, but I can not come up with any good way to control the relays when you want to lock or unlock the sliding door separately. As I see it, I would need 2x buttons. A momentary button to give the voltage at the terminals 86 so that the relays pull and then a further DPDT switch so that you can switch the polarity of the terminals 87. It seems a bit awkward having to press both a button and operate a rockerswitch so I have been looking for alternatives but failed to find anything. Would have been great if there was a momentary button that you could push in order to get voltage at 86 and then turning it to lock / unlock. The car remote key will be dominant so the relays may only pull for a short time while locking and then go back so you can use the remote control as usual. I suspect it would be possible to design a smart solution with eg an Arduino, PIC or similar , but this exceeds my knowledge so I would be very grateful if anyone can help me with a good solution.
C-lås - kopia.jpg
 

cowboybob

Well-Known Member
Most Helpful Member
Welcome to ETO, Rogge69!

Are you intending to alternate control of the sliding door locking mechanism between "normal" (ALL doors) and just the sliding door or a permanent change of sliding door lock control only from this new control?

Are you willing to sacrifice your lock/un-lock control of the sliding door from the key, fob and in-cabin controls?
 

alec_t

Well-Known Member
Most Helpful Member
Have you checked with your insurer that this won't invalidate your insurance?
 

Rogge69

New Member
This new control is ment to be an alternate function. All original controls must still work as normal. I'm wondering if it would be possible to add another couple of relays together with a 3 pole switch for generating a signal with varying polarity for terminal 87 and control to terminal 86 of them relays I've already drawn into the scematics?
 

cowboybob

Well-Known Member
Most Helpful Member
OK.

Can you please provide the Make, Model and year of your minibus? Going to need to see the vehicle's wiring schematic for how, exactly, your vehicle locking system is configured. "Winging" it often results in the law of unintended consequences rearing its ugly head...:banghead:.

Generally, locking systems are wired such that all vehicle locks are fed from a common set of relays. Basically, each lock/unlock motor is wired in parallel with all the others. Some vehicles have a "First un-lock" command that operates the driver's door only, with subsequent commands un-locking the remainder.

If nothing else, wiring into the sliding door lock motor harness, from the driver's side door (dash?) is going to be a bit of a bear. Not saying it can't be done, but...
 

Rogge69

New Member
Sliding door lock.jpg
BCM.jpg
Hi, and thanks for your reply. It's a brand new Volkswagen Caravelle and I have attached the scematics for you (sorry, the text is in Swedish). You are absolutely right about all locks are wired in parallel with each other and thats why it's important to break loose the sliding door lock circuit from the rest of the doors by feeding the relaycoils with a positive voltage on terminal 86 before locking or unlocking the sliding door, and this is where my dilemma lies. I was planning to break the circuit at T10bk/4 and T10bk/5 under the passenger seat and also mount the relays there but I can't come upp with a circuit that will both apply voltage on terminal 86 and simultaneously apply voltage with appropriate polarity depending on whether you want to lock or unlock the sliding door with only one switch. However it would be okay to have one pushbutton to lock and another to unlock. I have been in contact with a company that among other things retrofits equipment for the police and and received an instruction how they're doing. For VW Caravelle they do as I have shown in the scematic in my first post, the only difference is that they also fit a controllbox that handles all other additional equipment that is retrofitted, and the controlbox automaticly apply correct signals for the relays. However in this case when only the extra lockfunction is in demand it would be a huge overkill to mount such advanced and expensive box.
Sliding door lock.jpg BCM.jpg
 
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Rogge69

New Member
Made changes to the circuit diagram and added an on-off-on switch and a SPST relay, which pulls both SPDT -switching relays when you operate the DPCO switch (Learning some designations during the project).
Do you think this would work?
C-lås - kopia 3 - kopia.jpg
 

cowboybob

Well-Known Member
Most Helpful Member
So, you cut the wires from the ECU, energize the SPST relay, thus energizing the 2 SPDT relays (and removing the ECU from the circuit) and then alternate the DPCO away from OFF to lock/unlock through the 2 relays, Right? That will work.

One question: where is the + feeding the SPST relay coming from and how do you control it?

I forgot to ask: of the circuit(s) you've posted, how much of them are existing components/wiring and how much of it is (are) your proposed modification(s)?
 

Rogge69

New Member
This ought to also work? It will also be a relay less. power supply to the switch and relays should probably be via a fuse to terminal 15 (ignition).
I will cut the original cables under the passenger seat before they go out to the sliding door so most will be my own.

C-lås..jpg
 

cowboybob

Well-Known Member
Most Helpful Member
That will work as well.

Although it appears the ECU control will be reversed, i.e., an open command will force a lock.

(Could also be going blind... :woot:).
 
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