finding the right disarm wire

Ok, going by the 2nd post up top, I tested the "disarm" wire by putting the (+) lead from the DMM to a 12v+ source, and putting the (-) lead to the car's Brown wire that I thought was the disarm wire. It seemed to read a constant 12v, even when hitting the "disarm" button on the FOB. There were, unfortunately, 2 lt. green wires. I metered them both and tried them both, and no luck. I guess what I'm confused about is what should the wire rest at? If I connect black to the wire in question and red to a 12v+ source, then won't the DMM read 12v+ as if I'm testing the 12v+ wire?

Arg! Ok, I thought I had the dis-arm working, but apparently not. I had it hooked up and tested it so many times. I locked/armed the car with the factory fob, and then remotely started it without any problem. I did it a number of times in a row without any problems. But yesterday, after the car was sitting (armed) for about 5 hours, I came out and remotely started it and the alarm went off! I couldn't believe it. So apparently I don't have the right disarm or arm wires. I was using the FOB to test the factory security...I did not try it with the key in the door. Ok, so if I hook up the DMM (+) wire to 12v+ and the DMM (-) wire to the car's light green wire, should it rest at 0.0v? Then when I turn the key to disarm/unlock the car, the DMM should read -12v for a brief moment? Is that right? Or will it not read 0.0 at rest?