right front turn signal not working-back works.

well, they are telling me it's a harness??

Typically with these sorts of problems if it's not the bulb it could be a number of other things. Bad wiring/grounding out, the bulbs not making contact with the socket correctly as mentioned above, turn signal switch. It doesn't hurt to get a 2nd opinion especially if that shop offers free inspection/diagnostics. In the directory when you click on a shop it'll list Amenities. In that section you can find shops in your area that provide free inspections. www.repairpal.com/directory