It could be the Becker unit itself, behind the faux pass side firewall *or* it could be the wiring. I've heard of and experienced probs with the wiring in the door. Sometimes the window mechanism can mess things up, esp if someone has gotten the inside panel off in the past in order to repair a regulator or what have you. I suspect if you have a short the alarm would simply not shut off (in my case) or it's been disconnected altogether, probably your case. Good luck with the big Benz!