That's why the classic first step is to disconnect the loads (light bulbs and trailer relay, yes the trailer relay is a load) and then test the positive wires going to the front bulbs with a VOM and a separate known-to-be-good ground, like a jumper cable going to the negative battery post. Then, assuming the positive wires are hot when they should be and not when they shouldn't be, you put the bulbs back, leave the trailer relay disconnected, and test the front end lights. If one of the front bulbs doesn't look right, or behaves funny for some reason, switch the bulbs and see if the funny look or behavior switches with the bulbs or stays with the socket. All testing includes putting the turn signal/running lights bulbs through their paces both with and without the headlights on. That's the first step and that tackles the front end.
