Gents,

I have the standard driver's side door lock problem where you unlock the door and the alarm goes off (on my '90 300E). Per my searches, it appears that this is most likely due to a bad alarm microswitch. I have located a good driver's door in the junkyard and would like to extract the alarm microswitch for use in my door, as dealer has quoted me $146 for replacement part. I want to keep the alarm feature, rather than disconnect from box on passenger side floorboard. A couple of questions:


1. What are chances switch could require just cleaning as opposed to replacement?


2. Is use of junkyard part (on a pretty decent 300E) a really bad idea for this part?

3. Has anyone got a picture of what this part looks like?

Thx,

KermitF

The alarm microswitch is part of the tumbler/door lock assembly. They fail often so buying a used one is a gamble, may be nearly as bad as yours. You will also need to rekey the used tumbler to your key code unless you want to have 2 different keys. In my opinion you'd be better off buying the right party the first time.

Depending on the lock in the car you can buy a new micro-switch for the alarm. MB number 002-820-10-10 (LIST $109.) is the number for the left side. BUT that only fits lock numbers 124-760-07-77 OR 124-760-13-77! YOU must remove the lock first & check for those numbers.

You might ask Phil (here) on a $$$

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Benzaddict, MB Doc,

Will check lock w/fingers crossed that I have pn where microswitch replacement possible. (Thought junkyard electronics bad idea, but sometimes I am prone to stray in face of dealer prices. Will see Phil for help when I pinpoint need).

Thanks for your help here guys.

BTW MB Doc, do you have a shop here in Atl or are you at a dealer?

MB Doc,

I have finally gotten around to working on my ('90 300E) alarm problem. Removed driver's side door lock (the lock causing alarm to go off) and examined - including with a magnifying glass. Could find no PN on lock, but I can easily remove the microswitch from the lock (it just snaps off and on). Where would I actually look to find the lock PN? (I use same key for all door/trunk locks and ignition, so I presume any prior replacements had been done using MB dealers - most of records I got with the car show dealer work.)

I could just take switch into local dealer for replacement, but wanted to try Fastlane first.