My left parking light and turn signal began giving me trouble. When my parking lights or headlights were turned on, the left turn signal would illuminate steadly (no flash). When I would try to make a left turn and switch on the turn signal nothing happened. The emergency flashers worked normally. The turn signal indicator on the dash would illuminate at half brightness when the parking or headlights were turned on. The rear turn signal would also be on. The left parking light would not illuminate when the parking lights or headlights were switched on.
I read a bunch of stuff on google and replaced the flasher. No joy. Then I replaced the bulb 1157A. This solved the problem for now. I tested the bulb I pulled out. It tested fine with an ohmmeter. I then used a 12 volt power supply to apply power to this old bulb on both filaments. They both worked.
I do not believe the bulb was the problem. I think I moved a cable assy when changing the bulb and there was a bad connection to the ground wire for this bulb. The socket looked absolutely pristine. I am expecting this problem to recur. I have in mind to find the ground wire in the cable going to this light. I will cut it and splice in a separate ground wire to the chassis.
What does anyone think about all this??? Am I on the right track. I looked at the print in my manual and realized that a missing ground would back feed power to the panel lamp and the rear turn signal lamp. Just my thoughts.