The simple answer is you can't get there from here. The headlamp switch is part of the steering control module. There is no individual wire external to the switch that controls the high beams. The switch module is hooked up to the Totally Integrated Power Module via the LIN BUS, the Cluster, and the CAN Interior Bus. In short, when you hit the headlamp switch, you are asking the computer's permission to turn on the lights. The computer then grants your request - usually.
08 4 Door Rubicon
Member of Two Trackers 4wd Club
Great Lakes Four Wheel Drive Association
United Four Wheel Drive Associations