I replaced my driver side front turn signal bulb yesterday when I noticed it wasn't working. This is what it is doing now.

When the headlights are on:
1. Left turn signal will not work. Turn signal light and indicator light in dashboard burn steadily
2. emergency flashers will not work
3. right turn signal works ok

When the headlights are off:
1. left turn signal works
2. emergency flashers work
3. All dashboard lights flash in unison with the turn signal.

I included a photo of the turn signal lamp socket. You can see a little wire exposed. Is that likely the problem? Is it causing a short ground wire problem?

 

The bulb is not in the socket correctly.
A short to ground will blow a fuse.

 

Hi Pete,

When I took the photo, there was no bulb in the socket. That photo is just the socket. Please read the details again.

 

Most likely you have a short or two at that socket, probably just as easy to replace the entire socket than try to do a repair!

 

probably the socket and wiring from the looks of it, but also seen wrong bulb installed shorting the park light and signal circuit.

 

Are the old and replacement bulbs the same number? Are the latching tabs in the same location on both bulbs?

 

The bulb is Sylvania 3157. The new one is the same. One of the metal contacts on the old bulb
has a small amount of melt damage. I picked up a new socket pigtail at the parts store.

There might not be enough wire left in the wire bundle, to solder in the new pigtail. So I don't know if that will be a problem. I'm working on another repair. It might take me a little time to respond.

 

I soldered in the new socket pigtail. I still have the failed left turn signal when headlights are on. When headlights are off, left turn signal works ok. But I see a couple new developments.

-Dashboard lights no longer flash in unison with left turn signal when headlights are off
-Emergency flashers now work when headlights are on.

What next?

 

Have you cheked the flasher relay?

 

Hey Ben,

I was tempted to replace the turn signal flasher today. But it the flasher was faulty, wouldn't both turn signals fail to work? I can hear the flasher clicking for left and right turn signals.

Another new development. The left turn signal now works when the headlights are on. But the flash is weakened or diminished. Turn the headlight off, and left turn flash is full strength.

I'll crawl under the truck tomorrow and look for loose ground wires or bare wires. Already checked the engine bay. I might solder on a new left headlight socket for laughs, and see if that fixes it.

Also, one of the two license plate lamps keeps burning out over and over again. This issue could be connected to a tail lamp short.

 

would probably double check your socket you soldered on and make sure it is correctly installed the dual filament bulbs have one bright filament and one dim filament the bright would be for turn signal or brake and the dim is for park lamp circuit if you soldered the bright filament to the park lamps your probably not going to notice the signal working or it would be barely noticeable when the lights was on.

 

I was very careful to connect the wires in the same configuration as the old socket. I labeled old and new wires as 'left, middle, right' in relation to landmarks on the sockets. The new socket wires are not color-coded.

 

I found a broken ground in the lower engine compartment.

I'll post a photo tonight.

 

The negative battery cable is almost broken through. It's hanging on by some threads. I don't know if this is the cause of the left turn signal issue. I'll replace this ground cable and see if this fixes it. I might need one of those battery cable splice repair parts. It's obvious, so I skipped the photo for now.

 

I replaced the negative battery cable, and the weak left turn signal with left headlight on remains.

I wired the new turn signal pigtail just like the old one. But I wonder if the aftermarket socket changed
the wire positions or assignments? I'll probably replace the left headlight socket since it is so old anyway and see if that fixes it.

As far as the new left turn signal pigtail I wired in, how would I check it for correct wiring? The wires coming from the vehicle bundle are color coded black/green/brown. But the new pigtail is all black wires

 

would just probably pop out both sockets on the front turn on the park lamps and look closely at the left and right see witch filament is lighting up on each one if there different probably not wired right.
only 3 wires so one ground and 2 power signal and park lamps if both filaments are working would assume the ground is ok and just swap the 2 power wires retest it before permanently hooking it back up.

 

This test you recommend is a good idea, Alan. I didn't think of this.
But I still don't know which wires are ground, flasher, and parking light.

If I can find out which wires match up between engine bay wire bundle and pigtail, I probably only have to test the left front.