Rear light Dilemma

[Arde]

Test for my scenario is pretty simple. Measure resistance from the side of the turn signal socket (which grounds the bulb) to the ground wire attachment point on the back of the assembly and compare to the resistance from the side of the running light wire socket to the same ground wire attachment point. Equal resistance = no problem. Higher resistance at the turn signal socket indicates a problem.

Of course, in this situation, resistance of the bulbs is probably not similar, and that alone could be causing this problem.

I think I am starting to paint this scenario in my head. You apply 12V to the turn signal, that potential goes through the filament (with some voltage drop) but because the ground path between running light and chassis ground has significant resistance the net current is not enough to light up the turn signal nor to get intermittent cycles from the bimetal flasher. A constant voltage differential appears at the running light socket ground. What happens now? For a filament bulb I say nothing happens, the other side of the bulb is open and the voltage cannot create any current. For an LED bulb? I have seen weird things in the lab when a semiconductor gets only one of the rails applied... Worth exploring.

 

[Wobdog]

Sometimes walking away is needed to solve a problem. I needed to drive my car today so I put everything back in place and magically everything works. I suspected it was the ground and I guess it has to all be assembled to ground it.

 

[wkohler]

I guess it has to all be assembled to ground it.

That’s a t-shirt.

 

[Arde]

Bummer, I was about to go out for sushi. Now I have to eat a hat first.