(Headlight) Power flows from the HL switch to the dimmer switch/to bulkhead/out to headlights & start with the dimmer switch, which is either on the floor or in the dash. It has (3) terminals: the power in, power out to the low beams and power out to the high beams which lights up the low beam filaments at the same time. www.mymopar.com will have the colors for you. See if you have fire at the (2) bulkhead terminals (1 for low beams/1 for high/low together) & since you have neither I'd say start at the dimmer switch & if it has power in then work downstream (2 "out" dimmer switch terminals to bulkhead). EDIT I ain't familiar with a headlight relay & how it operates