I checked that car service checks many different parts like engine oil, filters, lights, brake, etc. I would assume they will tell you if something is not working. But will I be told also why something is not working? i.e. should I also expect them to diagnose the problem?
For example, say it is quite obvious that my tail lights do not light up, if I bring my car in for service, besides being told what I already know, will they also try to find out why the lights are not working (fuse, bulb, wire, socket, switch, software, etc.) as part of the service? Or diagnosing is always something extra?