Ok...seems that I have a better description of what is happening:

When using the key from the outside, only the door with the key is locked and unlocked.

When unlocking/locking the car from the inside with the car off, only the door with the key is locked and unlocked.

When unlocking/locking the car from the inside with the car running, ALL doors lock and unlock (system works).

When opening the door and the car is off, but the doors are locked, ALL doors unlock when you open the door (system seems to work).

Ring any bells?

Would really love for this system to work!!!

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2004 E320 Wagon W211
2000 CLK430 Convertible W208
1985 300SD W126
1983 300D W123