This weekend, I tried to install a single stage shock sensor into my factory alarm. I wired the negative wire from the sensor into a wire that only gets negative when the alarm is arm. The color is green with red stripe. The sensor's (+) into constant 12 volts. And the sensor's trigger wire into a wire that sets off the alarm, which is a gray with black stripe.

When i hit the car, the sensor does send a signal to the alarm but it doesn't set it off. This is the weird part. If I use a multi meter and set it to "batt", then touch the gray wire/black stripe with the positive lead and ground the other lead, the alarm is set off.

How can I use a relay to make this work? Or is there another way to make this work.

Thaks, Jason.