Tail lights not working, wiring question.

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rc51kid

rc51kid

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So my tail light/brakeligjts were both bad about 2 months ago. Put new bulbs in all was good. Now both dont work again. But new bulbs in and they still don't work. This time around the bulbs did not look blow.

I have power at the fuse and replaced the fuse in the dash listed as "tail". Rear side marker lights work, third brake light works, and turn signals work. I am going to grab a multimeter and start checking things. But can anyone help with where the wiring runs? I know it is in the rear quarters but does it go to one side then the other or any particular other electrical items I can check? Is there a large common plug that powers the tail lights AND turn signals that I can check? It's a little tight in the quarter panels. Thanks!

Edit: quick update. Good power at fuse. Driverside plug socket reads about 2.5v with the headlights on and truck running. Passenger bulb was also not on. I pulled that bulb and was able to read 12.5 v. I reinstalled it and messed with it and got it to come on. I think I got a flicker ou tof the driverside after that also. I am think that ng the bulb sockets themself are bad or have bad contacts. Does anyone know if the sockets can be disassembled? I am also going to check the plugs in the quarters becouse I do get water in there.
 
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Malleus

Malleus

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The schematic is (like all schematics) particularly unhelpful, unless you already know where everything is. You circuit is on page 25 of the components file (it has the whole truck in it).

To answer your pressing question, if you have power to the circuit, IME, the most likely fault is the hot connection in the bottom of the bulb socket. The front turn signal pigtails are notorious for this. I have resorted to an aluminum sheet, peeled off the paper gum wrapper, to overcome the corrosion. Fortunately, the rear circuit has a removable pigtail for the lights:
1638383053814

So, if your problem is in the sockets, you can replace the pigtail (for a mere $30) and move on with life.

1638382868879


1638382964398
 

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BILT4ME

BILT4ME

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We tore apart a friend's LC trying to find a similar issue. We had voltage at the socket, but not enough.

Turned out it was the short harness at the light.

$28 per side later and all was good. Well worth it to replace.
 
gummycarbs

gummycarbs

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I finally replaced my left, rear light harness. One thing that surprised me was how mashed down the center 'bump' was on the original bulb sockets. The bit that provides positive voltage to the bulb. I probably had intermittent lighting for years and didn't know it. Definitely worth replacing, and not hard to do.
 
rc51kid

rc51kid

Joined
May 31, 2010
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The schematic is (like all schematics) particularly unhelpful, unless you already know where everything is. You circuit is on page 25 of the components file (it has the whole truck in it).

To answer your pressing question, if you have power to the circuit, IME, the most likely fault is the hot connection in the bottom of the bulb socket. The front turn signal pigtails are notorious for this. I have resorted to an aluminum sheet, peeled off the paper gum wrapper, to overcome the corrosion. Fortunately, the rear circuit has a removable pigtail for the lights:
View attachment 2852986
So, if your problem is in the sockets, you can replace the pigtail (for a mere $30) and move on with life.

View attachment 2852984

View attachment 2852985
Wow that's cheap. I think I will give it a try.
 
rc51kid

rc51kid

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Thanks guys. I just ordered the pigtails and new rear belt moulding. Maybe new belt moulding will keep water out my rear quarter panels.
 
Malleus

Malleus

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Charlotte, NC & Alexandria, VA
Thanks guys. I just ordered the pigtails and new rear belt moulding. Maybe new belt moulding will keep water out my rear quarter panels.
You can be fairly aggressive when you remove the belt molding; the new clips are included. I'd recommend plastic body panel tools, or failing that, do what the manual suggests and tape the end of a screwdriver, so you don't scratch the paint. I bought one similar to this from Napa several years ago, but this one's much nicer, for the same price. I use it all the time.
1638453190966


I still don't know what the ring tool is for...
 
rc51kid

rc51kid

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Another update. I needed to get things working well enough to get to work. Cleaned the contacts really well and it didnt help at all. It had REALLY strange behavior. Tail lights would work until I hit the brake lights. Then both would stop working. Multimeter would still read 14v even when bulbs didnt work. Tail lights work with truck not running but didnt work with it running and so on strange stuff.I had all the bulbs pulled out from the tail light housing obviously. So when the light was working I started moving and pulling wires. I could get the driver side to go out if I pulled the white/black wire where it entered the bulb socket. It had a little play to it. This is the ground that goes to the metal housing and contacts the side of the bulb. I thing it was not conected to the housing well enough to power the bulb once they were drawing and real load. But my electrical knowledge is limited.

Since I have new harness ordered I dont really care about butchering the old ones. Sure hope the new harnesses dont turn out to be discontinued. So I basically skinned a small section of the white/black wire and ran a wire to the metal housing. I drilled a small hole in it and scuffed it well. My plan was to solder it to the housing. But my crappy soldering iron didnt get jk ot enough. So I got a little blob on there and a little of the wire through the hole. When I insert the bulb it is tight and smushed a little of the wire. It is really ghetto and temporary. Turned it all on and it is all working. Tail lights, brake light, running and not running.

It just made me thing again about how strange things can run when they have a bad ground. Also for some reason when the driver side does not work the passenger side didnt work. But the passenger can go out without effecting the driver. Power must go to the driver first maybe? Hopefully things will keep working until the new harnesses arrive. I will update again when they are in.
 

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