ml 320 power locking

Sounds like there is a problem with the lock mechanism itself. Have this checked out by a dealer.

I have a 1999 ML320 you do realize that you have to program the locks the drivers door will not lock unless door is closed it's programmed that way so you have to either use your key or your key fob to lock it after it's closed it's designed that way so that you don't lock yourself out of it with your keys in it to get your gas door to open you have to push the unlock button when the key is off and you're in park

I have a 1999 ML320 you do realize that you have to program the locks the drivers door will not lock unless door is closed it's programmed that way so you have to either use your key or your key fob to lock it after it's closed it's designed that way so that you don't lock yourself out of it with your keys in it to get your gas door to open you have to push the unlock button when the key is off and you're in park i hope this helps