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Discussion Starter #1
Howdy All!

Thanks for the add.

I am installing an UNGO MS8200 car alarm in a 1989 VW Vanagon (with factory power doorlocks). The VW system requires a 12v+ trigger for both the "lock" & "unlock" circuit which are 2 different wires.

The Ungo lock trigger wires (2) provide a negative ground signal at all times EXCEPT momentarily they provide a 12v + when either armed or disarmed (1 wire provides 12v when armed; the other wire provides 12v when disarmed). After the momentary 12v+ either circuit returns to providing a constant negative ground signal. The locking system in the VW doesn't like this. I guess my question is:

How do I wire in relays to maintain the 12v+ momentarily but delete the constant ground signal that the Ungo brain is outputting?

Any help on this is appreciated! I have tried relays in several configurations but haven't found one that works. The Ungo manual makes it seem that the system should output a 12v trigger without relays but it's the constant -gound (I think) that's throwing me for a loop.
 

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Simple really. Use two relays to help isolate and buffer the (+) triggers from the alarm.
On the two relays:
Pins 87 to 12V constant
Pins 85 to ground
Pins 86 to the lock trigger outputs from your Ungo
Pins 30 to the factory door lock wires
 

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Discussion Starter #3
Simple really. Use two relays to help isolate and buffer the (+) triggers from the alarm.
On the two relays:
Pins 87 to 12V constant
Pins 85 to ground
Pins 86 to the lock trigger outputs from your Ungo
Pins 30 to the factory door lock wires
Thanks for the reply! I spoke to an electrician relative of mine who only knows a little about 12v electrical but he suggested using isolating diodes to filter out the ground current. I am guessing both methods would achieve the same results.
 

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Yes, you may use diodes as well. You will want to orient the diode so that the cathode (striped side) is connected to the wire in the vehicle.
 

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Discussion Starter #6
Yes, you may use diodes as well. You will want to orient the diode so that the cathode (striped side) is connected to the wire in the vehicle.
So far it hasn't worked. I tried installing the diodes but the locks won't trigger. I believe the problem is that the 500mA output from the Ungo isn't sufficient to trigger the locks. I have verified the following using a test probe:

My test probe lights up when I arm/disarm the alarm from the ungo's power door lock wires.
Only 12V+ is getting through the diodes (no ground current).
The Power locks do trigger when I hot wire 12v directly from the fuse panel.
They also trigger when I unplug the 2 lock/unlock wires from the ungo & run 12v power from the fuse panel through the ungo wires (with diodes inline).

I am thinking that I need to go with the relay setup unless there is a way to increase the amperage coming from the Ungo to trigger the locks. It seems strange that this wouldn't be sufficient. Is it possible that I am overlooking something else?

Thanks,
Jon
 
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