Headlights and front turn signals share a common grounding circuit at right side pof engine compartment, behind the headlights on inner fender at lower position. You might have to remove the battery to check. The grounding circuit could possibly be loose or contaminated or damaged by presence of battery electrolyte which has overspilled onto them.
Symptoms indicates the headlights is not getting sufficient ground and when turned on, voltage is moving backwards along the turnsignal circuit causing the blbs to illuminate.
Use a remote ground wire to ground the Black wire at headlight low beam bulb to test.
Tuesday, January 2nd, 2018 AT 2:43 PM