Weird intermittent bulb failure...

[Klutch9]

Over the past week, the front turn signal/parking light bulb (2357A, dual filament twist-in bulb) does not work. I first noticed this when I used my fob to unlock the vehicle, and the turn signal light did not flash on the drivers side. Instead, the side marker bulb flashed, which shares a harness with the turn signal bulb.

To make it even weirder, when one filament isnt working, neither is the other. When one IS working, then BOTH work

But the side marker bulb that this bulb shares a harness with always works, regardless. I pulled the 2357A bulb to check for any sort of damage, broken filaments, incorrect installation, and I came up empty. It almost sounds like a bad ground and/or voltage supply, but I'm curious as to why the side marker bulb still works, and even takes over the flashing duties when I unlock the vehicle with the fob. I bought a new bulb, so maybe swapping the bulb might be a good idea, but the current bulb looks just fine.

The most curious thing in all of this is, as I've stated, that when one filament ceases to work, so does the other, even though they each have their own lead on the socket...

 

[Cardenio327]

Originally Posted By: Klutch9
and even takes over the flashing duties


^Sign of a bad ground.^

 

[JR]

All signs point to a faulty ground.
the sidemarker works so it power and ground is good, it shares power with faulty light so it only leaves the ground.

Ken

 

[eljefino]

Some side markers are wired in series between the park hot and turn hot. When there's a difference between the two, it flashes. This way it flashes in phase with the turn signal sometimes and out of phase other times, depending on parking light status.

When the parking lights are on, the turn glows very very dimly, unnoticeably so. As the side marker light is more effecient, it gets most of the voltage per ohm's law.

Yet I agree, bad ground in the main socket.

I'm explaining it poorly, so here's a diagram:

 

[Klutch9]

Originally Posted By: eljefino
Some side markers are wired in series between the park hot and turn hot. When there's a difference between the two, it flashes. This way it flashes in phase with the turn signal sometimes and out of phase other times, depending on parking light status.

When the parking lights are on, the turn glows very very dimly, unnoticeably so. As the side marker light is more effecient, it gets most of the voltage per ohm's law.

Yet I agree, bad ground in the main socket.

I'm explaining it poorly, so here's a diagram:

But I just noticed a few other things...

1) I went outside and turned the parking lights on. Side marker was on, but the parking filament in the 2357 bulb did not come on. So I banged on the headlamp housing a few times, and it turned on and stayed on. Interesting...

2) After a few minutes of being on, both bulbs simultaneously turned off, without me touching them or the lighting control on the stalk. So I flick the lights off on the stalk, then back on, and both bulbs come back on. This happened twice.

This makes it even more odd. I'd turn the parking lights on, verify operation, and then I shook, twisted, prettymuch everything short of mutilated the wiring harness, and they stayed on without a flicker. So it seems that the wiring isnt an issue. The only thing I noticed as a potential problem was inside the socket of the 2357 bulb, there is a contact strip on the side that seemed kind of stuck. So I bent it out a little. Other than that, I dont know what else I can do. The "lighting" portion of the stalk on the steering column has a slit in the back where the wire feeds in for the lighting control. I wiggled and prodded it, but the lights continued to work as normal. The most interesting thing to me is why both lights (side marker and main bulb, including turn signal) turned themselves off after a few minutes, then happily turned back on after cycling the switch