OEM Alarm Wiring Help Needed

[Gadgetjq]

Tech question here gang, two local dealers shops don't have a clue.

I just purchased a motion (microwave) detector to mount inside the convertible, just to keep nosy hands out of the cabin when it's parked. The unit is very small and designed to be plugged into a port available on most aftermarket alarm systems.

What I want to do is connect it to the OEM alarm and what I need is a guide to the "Trigger Wire". I know the OEM system counts on a door, hood, trunk opening and completion of a circuit to ground to set off the normal alarm but this little thing puts out a 200mA signal, presumably to trip a relay.

Do any of you electrics guru's know what wire I need on the car (assuming there is one) to make this little guy work?

There 'is' some aftermarket alarm system wiring installed for the dealership with about a dozen pins on the connector, four of them are ground and the rest unidentifiable without a schematic. I thought about touching the output to each wire but one or more of those might disable the starter (or worse) so don't want to apply power blindly.

Once I get it sorted out I'll post the fix for everyone else. This could be $10 well spent or wasted.

Thanks,
Gadgetjq

[[SMAN]]

Well, the way i see it, you need to be able to trigger the factory alarm. Your sensor outputs 12V when it is triggered, then you need to trip a relay to switch that output to a ground signal. The way to trigger the factory alarm is to just trigger one of the door courtisey switchs. To do that, it just needs to be grounded. I have included a picture of the wires in question, the ones with a (*3) are for the coupe and the ones with the (*4) is for the convertable. Just tap into one of those wires and you should be set to go.

[Gadgetjq]

Thanks Sman, you've been a huge help.

Connecting the output to a relay to ground the door switch was going to be my "plan B" if I couldn't locate a dedicated wire. Now I know to look for green/red or red/green.

The trigger output of the device is really low, only 200mA so guess I'll need a really small relay.

Cheers,
John

[[SMAN]]

200ma should be enough to trip a standard 30 amp relay, you don't actualy need to show much ground to the system because it is a low power trigger on the door wire, so a simple transistor would work as well, but a relay will work fine too. These wires can be found in the kick panel in the corner by the door, or at the ecu behind the fuse panel. Let me know if you still need help, but i'm surprised your shop couldn't figure this out cause it only tooke me a few minutes, because even if they were gonna install an aftermarket alarm, they would need to use those wires to trigger an open door for that as well.

Here is a diagram to show you how to wire the relay to convert your output properly.
http://www.the12volt.com/relays/page1.asp#p2n

[philosophicaljt]

this is sweet.