Drivers side remote lock doesn't lock or unlock or lock at 15 mph.All other locks work.Thinking it is the actuater called dealer and the price to replace it is $612.00.Could it be something other?

 

If you tinted windows recently it might be those guys not flly engaging the connectors.

 

If you "trouple" door locks/unlocks when standing still - but doesn't auto lock at speed - I would try resetting the auto lock feature - off - drive 5 minutes - turn GLK off - then turn GLK back on and "enable" - page 124 US manual from mbusa.com - might help -

 

Thanks but windows were tinted 5 years ago and I tried sitting in the car trick so not that.Drivers door the only one not working.Checked DYI videos but out of my level so will have to bite the bullet and pay the man (dealer).