My drivers door will not auto lock with with the key fob or when the car goes over 10mph.  It sounds like it's trying to but it just wont lock. It will lock if I turn the key in the barrel of the door though.

 

Is this likely to be the wires in the loom or the actual lock mechanism? I'm guessing it will be the mechanism as if the wires had broken in the lom.it wouldn't try an lock would it? But on the other hand, if it was the mechanism would it lock with the key in the barrel? 

 

 

Forgot to mention, I'm getting fault code 03301

Wires ould be snapping and making some contact but not consistent. Worth a good look at both front door wiring looms.