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Alright I tried searching for some threads but came up empty. I just rewired the tail lights on my 66 all the way from the engine bay to the pigtails. (Did not replace pigtails). I did this because my left tail light stopped working. It’s now working again HOWEVER the brake light is stuck on as well causing it to be brighter than the right right side. The turn signal also won’t work if the tail lights are on because that filament is already stuck on. I don’t think I did anything wrong, the harnesses only go together one logical way after all. I’m stumped on this one but admittedly don’t know much about electrical stuff.
Did you solder all the connections? If you used crimp lugs that could be a problem.
How is that a connection is a connection.
I hate to say this but you did something wrong.
As a test if the tail lights are off do you get brake & turn signal lights on the sides they are turned to?
If yes you did wired it wrong.
Each bulb has 2 filaments 1 a little brighter than the other.
The dimmer 1 is the tail light filament and the brighter the brake / turn filament.
You will need to swap the 2 wires at each light assy. and it should work like the factory wanted it to work.
Before you go making any perament connections test to see if you have the right wires to the right filaments.
Good luck
Dave ----
If your light stopped working, it is likely a grounding issue. Brake & turn share the same filament. Don't know what you crossed but it is likely at front with flasher.
If your light stopped working, it is likely a grounding issue. Brake & turn share the same filament. Don't know what you crossed but it is likely at front with flasher.
John
If I under stand it right he never touched the flasher(s) so how could that be?
He replaced the wiring down the frame rail from engine bay to rear lights.
That would be 4 wires (L stop /turn, R stop /turn, running, back up lights) maybe 5 if there was a ground wire run with them like on the newer trucks.
If he was to swap the running lights for the stop / turn he would have bright lights when the running lights are on and he would not see the dimmer now turn / stop lights.
That is why I asked him to leave the running lights off and try the turn / stop lights.
If they work and are dimmer he has the wires crossed and needs to swap them around.
Dave ----
If I under stand it right he never touched the flasher(s) so how could that be?
He replaced the wiring down the frame rail from engine bay to rear lights.
That would be 4 wires (L stop /turn, R stop /turn, running, back up lights) maybe 5 if there was a ground wire run with them like on the newer trucks.
If he was to swap the running lights for the stop / turn he would have bright lights when the running lights are on and he would not see the dimmer now turn / stop lights.
That is why I asked him to leave the running lights off and try the turn / stop lights.
If they work and are dimmer he has the wires crossed and needs to swap them around.
Dave ----
You’re correct I just replaced the two harnesses along the frame and back to the tail lights. Both harnesses are from Carpenter and the two pin connectors can only go together one way which is why I didn’t think anything was crossed. But the symptoms you’re describing are accurate. When the tail lights are on it’s brighter and when the flashers are on it’s dimmer. And then with the twilights and flashers on it won’t even blink. I’m wondering if it’s a manufacturing error, but I’m either case it looks like a wire is crossed. As I said before I know nothing about automotive electrical but I’m guessing what I have to do is cut and strip the wires, cross them and splice them back together? There is no ground wire coming off the harness just a little 1 pin for the license plate
I wouldn't cut and splice any wire on a brand new wiring harness. Instead perhaps use jumper wires to connect the harnesses with the wires swapped at the jumpers. Then if you figure out what is swapped I'd contact Dennis Carpenter and review with them. I have several NOS harnesses for the taillights themselves that I can take pics of for wiring colors, connector orientation, etc. if you'd like. I don't have an NOS intermediate harness but I do have the originals on my trucks.
What happened to your originals? Are they still around such that you could compare close-up?
I have found grounding issues in the taillights have been the cause of many of the problems in the electrical circuit, whether it be the sockets with the pigtail connections, or bulb sockets possibly corroded or aftermarket foreign-made bulbs where the retaining pins are short stubs and barely hold the bulb in the socket??
I have disconnected the taillight harness and connected the small square type 9v battery and alligator clips to the leads and perhaps able to isolate the problem???
Sounds like FuzzFace2 is on the right track, and I would just like to emphasize what Dave and John have said - the biggest culprit for taillight issues is grounding. Make sure the grounding features are bright shiny metal. I have had some real head-scratchers that good grounding fixed. I always apply a very light coat of grease to deter new corrosion. (I use pure silicone grease, common in electrical work, but I think any could do)
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a connection is a connection.
