Low beams

The circuit depends on whether you have automatic head lights and/or daytime running lights. You should be seeing twelve volts on the yellow wire for the low-beam light. The two yellow wires for the two low-beam head lights come from the under-hood junction box, but on different terminals. That is the box the low-beam and the high-beam relays, and their fuses, are in. All versions use terminal 31 for the passenger low beam and terminal 73 for the driver's side low beam.

The splice for the two lights is in that junction box. There has to be a break somewhere starting at that splice, to the socket where you found the twelve volts missing. If you can find those yellow wires at the junction box, check there for twelve volts. If you find it there, inspect those wires for a break.