High Beam Headlights

I have a 1999 Dodge Ram 1500 quad cab with 5.9 engine. I have a problem with my high beams. The headlight on the right hand side is not getting power for the high beam to work ( low beam works fine). I am trying to trace the problem but am having trouble finding the wire under the front behind the aie dam. Any suggestions on where to look or what to do?

i'm not sure how you're checking this but if you have power on the low beam this is the same feed for high beam in this model year the switch toggles the ground side and not the 12v anymore

I have checked this by unpluging the wire at the back of the light and checking the voltage across the three terminals there. On the right side of the truck ( the one with the working high beam) I get voltage at all 3 terminals. On the left hand light, I am only showing voltage on 2 terminals.

Thanks