Almost certainly you're going to find a broken ground wire for the left front bulb. Current goes to the left front signal filament in the dual bulb, can't get to ground, so it looks for an alternate path. That is through the running light filament, over to the running light on the other side, then to ground on the right side. The proof is the left bulb will turn off if you remove the right one.
Saturday, May 23rd, 2015 AT 7:59 PM