So I've been finishing up the wiring and stuff in the interior of My truck since the rebuild. Yesterday I ran and hooked up the wiring for the Ambient temperature for the panel with the interior lights, mpg etc. To the Fuse panel, and out to the front of the hood. All the sudden I have no low beams. High works, running lights work. But no low beam. Any suggestions

 

2 or 4 headlight system?

 

Each side has 2 pieces, one for headlights one for blinkers, high is outside, low is inside

 

4 headlight system then? Sport Model Truck??

 

So I actually figured out the headlights issue, or it figured itself out rather lolAnother question you may know the answer to.
Behind the plastic that runs from roof to floor rear passenger side. There is a wire harness that runs up to the brake light above the window. On that harness is a plug, any idea what that plug goes to? The interior roof lights are already wired.

 

Maybe for cargo lamps, or, a sensor your truck doesn't have.