I looked at you headlamp switch, I'm not sure what you mean by third position? Usually if the low beams work and the high-beam doesn't, I suspect the dimmer switch. In the diagram below, lite green wire is voltage for high beam, black is ground. For the low beam, tan wire is voltage and again, black is ground. Use a voltage tester, on high beam voltage circuit, headlamp on high.
Monday, January 31st, 2011 AT 6:29 PM