I have a 89 560SL that has recently started having problems with the door locks. I have an after market alarm installed that apparently 'hooks' into the door locks, etc. Just recently when I start my car, my passenger door lock locks, then reopens. The driver's side never locks. My mechanic thought it was the passenger door & replaced the handle - but my problem is still there. He claims that it worked at his shop & its my after market alarm. He hates after market alarms. He also tells me that I should NEVER have my doors locked while driving anyhow! When I am in my car & manually lock my drivers side, it does lock. When I unlock it, I hear the vacuum on it for about 20 seconds--not sure if that's normal. Also a few times, I've been in the car, manually lock it & the Mercedes alarm goes off. I have to get out, lock & unlock the car & get in again. And leave my doors unlocked. I did have a problem several years ago where something similar to this happened & it was some kind of mechanism in the trunk? Which was replaced. I went round & round on that bout too-- having my after market alarm disconnected & reconnected about 5 times until someone would listen -- also taking it to 3 different shops... Anyhow, short of having the after market alarm disconnected -- any other suggestions? Anything I can look at or do? Help!!! I'm very frustrated!