Fitting a remote central locking system to a pneumatic B2 system

[BackintheFold]

I tried fitting one yesterday. A cheap eBay one as per Nobbly.

I couldn’t get it to work. I think this may be because of the way the switch in the key lock applies power to the pump.

It may be possible to remove the key based central locking from the system and get it working. The keys would still lock/unlock but not affect the central locking.

I ran out of time (and patience!) with it so will try again after I’ve sorted the clutch.

[Hanuman]

Do you have any details?

The quattro/Audi system of the era is a little ‘lacking’
Were you to be A gentleman, and open the passenger door for your companion first, then you’d need to open your own door independently.
Rather pointless as a system. Or half pointless… Or half a system….

I used to have a remote closing system on mine, and it really was more a liability. What is really needed is something that acts directly on the pump input, electronically, rather than by hanging onto the door actuators as most appear to do.

[BackintheFold]

The one I have is set up to give 12v for 3.8 seconds on one wire when you lock, and the same on a different wire when you unlock.

If you plumb this into the system without cutting the connection to the key switch, you end up with 12v to both activation wires.

As you know, the pump has two wires. When you lock the door, one wire is changed to permanent 12v until you unlock the door, when the other wire gets 12v.

If you cut the wires to the key switch, it should work off the remote, and the keys will still operate each door but not the central locking.
I tried that yesterday but it didn’t work.
I had to stop before I could investigate further.

[Hanuman]

I started looking at something like this some time last century (it might have been early this century.)

B2 era cars had what I describe as a single channel pump, and a single door actuator having an electrical connection. I thought the connection was momentary. ie. You turn the key, to lock, and it returns to centre. You turn the key to unlock in the other direction, and it returns to centre. I just can’t remember.

Later, all the pumps, although looking similar, had two channels, and both Driver’s and passenger door both had actuators with electrical contacts.
I think, but don’t know for sure, that the flagship t44 fleet had the later iteration from quite a bit earlier in the build.

Quite frankly, Audi might have been better off putting the actuator on the passenger door. Then, if you were alone, you only unlock the drivers door. If you were with company, you centrally unlock all the doors.
Better still, they should have just had the dual version from the outset. I think the circuit board had provision for the components.

Ultimately, what’s needed is a way for the pump circuit to be told to trigger off the input from whatever control box. So if there had been an unlock and a lock function, each would be fed to the respective side of the pump. But if this is a single impulse, then I think it would need some other gizmo in between your box, and the pump to interpret the sense. I could see a simple flip-flop circuit doing it.

[BackintheFold]

For the 1988 ur, and others, there is a contact in the door key switch that makes one wire positive or the other permanently.
Those two wires go back to the pump that has a central earth and two other connections. 12v on one and the pump sucks. When the door knobs are both down, the vacuum increases and pulls a physical switch in the pump. This stops the pump and sets it to wait for a signal from the other wire.

When the key is then turned to open, the positive goes down the other wire. Because the pump has moved a contact over, this makes the pump blow. When both door knobs are up, the excess pressure now flicks the pump's internal switch the other way and the pump stops. Again, the pump can now wait for a signal from the other wire.

There is no vacuum connection to the driver's door! So the whole "central locking" thing in an ur is just the driver's door operating a pump to open the passenger door...

[Sandro]

That's why I'll go for "normal" electro-mechanical central locking + alarm system for my C2. Not sure if that would be the case for my V8 since the pump is alarm itself as well.
Why Audi ever had to come up with the vacuum system?

[BackintheFold]

Tried this again today. Everything is set up properly, but some times it works perfectly and others if doesn’t.
That would be too frustrating for me to use day-to-day so I disconnected it all and put interior back together.
I can live without remote locking!

[BackintheFold]

Yeah. So I had another go and figured it out.
Anyone fitting one to a B2 era Audi who finds it works intermittently…pm me your number and I’ll talk you through it.