bmw alarm

I have a e36 1995, came from Italy, with a Gemel alarm (control unit and siren). The problem was in disapearing of

the siren sound. In a forum I found that the problem may be in the siren batteries, I replaced them, with no effect.

Now it is dead. I found a siren from an e38, Gemel too (I think), most e38 and e39 equiped with it. So on my siren

there are 6 wires, on a new one only 4. I connected the brown to brown (-), red to red(+), PURPLE / white (trigger)

from control unit to BLACK/ blue of siren, and everithing works. But I am afraid there is no charging of batteries.

When I connect the BLACK/ red from control unit to BLACK/ red of siren a 4mA current appears in the red - brown

circuit (without it 0.4mA), so I suppose this BLACK/ red wire is responsible for charging, but with this wire

connected the alarm begin to make noise when I turn the ignition off (1 from 3-5 cases) (and there is a voltage drop

from 12V ign on to 7V ign off on this wire). By the way on my old siren shortcircuiting this BLACK/ red to red by a

key in the glovebox the siren became quiet. The remaining 2 wires from my old siren are the second brown and a

WHITE/ black with a 0.15V on it.
So, what is the BLACK/ red responsible for. If charging - I shoud connect it, then what to do with the activating

siren when ignition off. And how to make the siren quiet (sound only when disturbing the car)
PS The new siren begin to make noise when disconecting any of these 4 wires, even if I do not activate the alarm,

the old one did not.

Plese help and sorry for english and techn. I am a neurosurgeon.

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BMW 320, e36, september 1995