My new (to me) '85 300CD-T has the factory installed alarm.

The master key for the car (square headed) will lock/unlock door & enable/disable alarm for the driver's side of the car just fine. On the passenger side, the same key will only enable/disable the alarm - it will not actually lock or unlock the door. Is this the way this is supposed to work? My '83 300CD-T doesn't have the factory alarm and the master key will lock/unlock anything on the car with a lock.

Perhaps the door handle/lock on the passenger door of the '85 has reached its limit of wear?

Any clarification/help appreciated. Thanks-

Terry

It sounds like a door handle tumbler problem, the key should work as it does in your 83 300D.

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MB Medic
14 year MB tech
7 year shop foreman @ independent MB/Volvo shop

Thanks for your reply-

This sounds like my first opportunity to delve into the door handle lock/alarm combination...

Do you have any idea how the alarm is integrated with the door handle lock? Does it seem feasible that the alarm enabling/disabling would be okay while the actual moving of hardware (disengaging the door's lock) would fail? Another way of saying that is: If the tumbler were failing, wouldn't the lock *and* the alarm both malfunction? Thus I'm wondering how the alarm integrates with the door handle lock...

Thanks you for your help and insight!

Terry