Join Date: Jan 2005
Location: San Juan Capistrano
You have done a good job of describing the classic symptoms of a bad ground at light housing. Since there is no path to ground at the housing, current will run through the turn signal filament, and then back through the parking light filament and on to the other lights on that circuit. Since the parking light is a lower wattage (= higher resistance) load, it will be the one that shines.
These housings typically are just grounded through their attachment hardware. If the nuts & washers that secure them are contacting painted/rusted bodywork, the housing isn't grounded. Sand off the paint/rust, and things should return to normal.
San Juan Capistrano, CA
'65 Guilia Sprint GT
Last edited by Alfajay; 07-20-2018 at 09:52 AM.