The fuse for that circuit is #20, 10a in fuse box under dash. That fuse powers other things so you would probably have additional problems if it was blown or had no power ( HVAC, flasher unit,). The switch gets power directly from that fuse so you can ignore other things like shifter, PCM etc, other than a connector or two and maybe a splice or two. If its not a fuse you will have to trace the wiring for an open circuit or loose connection somewhere