the same wires going into the sw. works both sides so if the left side works that means everything going into the switch is good, if the wire going to and the light on the right side is good then all that is left is the sw. do like denny said, go under the dash, find out which wire goes to the r/r and jump 12v to it ,if the light works then its the sw. i donk know what the mech checked but look like he was just guessing. im taking you word that the light is good if it is its the sw.