2002 dodge dakota sport club cab 4.7l manuel 4wd.

bulb is good
ctm fuses are good
im not getting power at the wire plug that plugs into the headlight for dims
brights work.
previous owner wired a switch from battery terminal in the fuse box that will turn on the dims so bulb works. he spliced into the purple/red wire on the plug without that switch on that wire does not get any power with the lights on. where could the wire be losing power? somewhere in the harness or headlight switch?

 

You can find wiring diagrams for your truck here. Check it out, see what presents itself.