Rear Driver's side automatic lock doesn't work.

So this has been bugging me for awhile, but now I want to try and fix this. After I went in for the wire fix in the steering column safety recall my rear driver's side door automatic lock doesn't work (by key fob or door panel controls). I have no idea what happened, but it just flat out isn't working.

I've tried contacting the local dealership about it, but they won't look into it without charging me. Since I don't really have any proof to say whether or not it was just fluke timing that it went out the same time they fixed the steering column issue, I figured I would try to fix it myself if possible.

Anybody have any ideas what it could be? Or how hard it would be to troubleshoot this?

 

Sounds like the actuator went out...they're like $60-120 from dealership. It's easy to change out (mines starting to go out on the same door)
Probably going to change it out soon as well