I have an aftermarket keyless entry/alarm hooked up to my central locking system on my 95 E320 (W124). It works flawlessly. However, I would like to hook the keyless entry up to the factory alarm. I found two wires in the trunk, next to the trunk lock, which activate the factory alarm. Using my multimeter, I checked the wires. When I activated the factory alarm using the trunk lock, the hot wire dipped from 12V to 0V for one second, then returned to 12V. So I assume the change from 12V to 0V and back switches the factory alarm on and off. However, when I hook up the aftermarket alarm to this wire with negative polarized relays, I can't get it to activate the factory alarm. In case you didn't notice, I am an electrical amateur. Any help would be greatly appreciated.
'95 E320 Sedan w/224K Miles (W124)