Sorry about another post on door lock actuators, but I am trying to work out a paradigm for isolating the ones which need replacing. 2002 ML 320.

A search has given great info on the r/r, but not too clear on diagnosis by function.

There seems to be little logic in the behavior at this time. With locking initiated can one assume the doors which are not locked have the failed actuator? I am concerned that with a failed actuator, the system has a failed input, and that actual lock status may not be accurate.

If doors are locked with key fob, can I assume that the failed actuator/s are the ones which have not locked? I get the alarm sounding, when some doors are opened which should be locked, can I assume that these door actuators have failed.

The fuel door seems to always be locked, but I suspect this may be due to bad input to the system from a failed actuator.

Thanks

Marty