1995 E320....driverside wont lock

[ontime-njoy]

Hello ' I got a 1995 E320 Mercedes . The driverside wont lock with the key .It seems like its lock ,the little pin on the door goes down indicating its locking ,but if I open the door the Alarm goes off and door opens up .All other 3 doors lock fine .It happened about 6 months ago .At first it was intermittent but now it never locks .has anyone encountered this problem and would tell me what it is please ?

[softconsult]

I have read some posts over the years discussing worn out drivers door lock and alarm system going off. Suggest search on maybe w124 Lock Alarm or 300E Locks Worn etc.

Steve

[J. M. van Swaay]

When you lock/unlock from the drivers door, do the other door lock plungers also lock/unlock? When you lock from drivers door, does alarm arm? (can be verified by blinking red light on center console just to the right of emergency flasher switch.) When you unlock from drivers door does alarm disarm? (check for absence of blinking light after unlocking but prior to opening door)

There are two switches associated with the left front door lock/unlock, and alarm arm/disarm. (S47 and S62/1 on MB wiring schematic) S47 is part of the plunger mechanism and signals the vac pump to lock/unlock other doors based on plunger position. S62/1 arms/disarms the alarm and is only actuated when using the key to lock/unlock.

Without more specific symptoms, it's hard to say what the problem might be. Based on your post, it sounds like the door can be locked/unlocked but you have a problem with the alarm. From this I would conclude a bad alarm switch (S62/1). It is accessable by removing a black plastic plug on the back edge of the door just above the exterior door handle.

[ontime-njoy]

All plungers work fine except the driver side one that works intermittently .I can use the key to lock the Door ,The plunger does go down but the door wont lock .The Alarm gets activated when I lock and unlock the driver side Door .Everything seems to work fine but If I open the door without using the key ,it opens up ,the Alarm goes off .Awhile back the Alarm would go off by itself during the day ,I would had to run ,unlock the door to disengage it .That has happened lately though . Can it be a bad Lock ?????