(1) push the dimmer switch to "low beam" & pull the connector off & see if the specific switch terminal is hot (2) if not clean or replace the switch (3) if its hot plug the connector back in & pull the connectors off of the low beam lights and see if the specific female connector terminal (the one from switch low beam terminal) behind each light is hot. (4) if not there is an open rearward to the dimmer switch (check bulkhead first) (4) if both are hot then ohm the male terminals on the low beam headlights to check for an open. I'm thinking there is 1 ground for each side of the vehicle (1 low beam/1 high beam), it's been awhile & it must already have continuity to ground as you are getting some filaments lit up but do some checking & holler back. EDIT the violet with tracer wire is the low beam circuit (1) see if it is hot at both low beam lights (dimmer on low) (2) if so pull the connector off of each low beam bulb and ground the bulb male lug the black wire connector was on & (3) jump fire to the high side (other end "red wire" male lug) & see if it lights up and (4) Then jump fire to the low side (middle male lug that the violet wire was on) & see if it light up (check both low beam bulbs) & not likely both lights went bad so see what develops