Hi Im new to this so please go easy on me, I have recently brought a 51 plate a4 tdi and have noticed that the drivers door is not locking or unlocking with the key fob. I have done a lot of searches on here and read a lot but nothing is giving me a definative answer or at least what i want to hear.
Here it is summed up:

All windows work fine from drivers door,
speaker works,
electric mirror controls work,
door lock buttons will lock and unlock all the other doors but NOT the drivers door.
Door will lock and unlock from outside with key,
have checked wires from car body to door and all look ok,
have felt carpet in the passenger footwell and all is dry and lovely.

I havent pulled the door card yet but my gut feeling is the door lock mechanism/motor is knackered, Im not thick and can figure most things out but this I want to check before i start breaking or replacing bits that i dont need.

Is there a way of checking the door lock motor, or at least which wires are feeding it and what volt reedingd they should be giving out, if you see what i mean.

Please any info would be great

many thanks adam