I need some tail light wiring help, please....
 

Working on the project - 1965 SWB Fleetside. I am trying to get the tail lights working with blinkers, brake lights, etc... Over the years, someone did a hack job on the rear taillight harness and there are splices of different wire everywhere. Here is what I have at the plug for the harness:

1. Black/Yellow wire lead
2. Black lead
3. Dark Green lead
4. Yellow lead

Can anyone tell me where or how each lead needs to go...? I was able to play around with it a little yesterday and got the brake lights, running lights, and signal lights working UNTIL you turn on the headlights, then the blinkers just hold and do not blink. The plug has had the wires spliced off with only about 3 or 4 inches on them, so the original wire colors are all gone...

Appreciate any help...

Re: I need some tail light wiring help, please....
 

I use a trailer wiring harness to clean things up...go back to someplace the harnesss is clean the take your time and spice in the new wire..the colors will even match up...I'm not going to guess what colors go where ( I'm having CRS right now) but on the box it will tell you everything its standard

hope this helps

http://67-72chevytrucks.com/vboard/s...d.php?t=185856

heres a diagram for our trucks you can follow

Re: I need some tail light wiring help, please....
 

I went through the same thing with my tail lights and would get it figured out and they would work for a little while then go out. I got tired of chasing the gremlins and broke down and got both front and rear tail light harnesses. the best $70.00 bucks I ever spent.

Re: I need some tail light wiring help, please....
 

I looked in the LMC catalog and they say a 4 to 6 week wait on a harness. Any other recommended places I might be able to pic a harness up...?

Re: I need some tail light wiring help, please....
 

Does this help at all? I have a pdf I can email you if you can't read this one.
http://i117.photobucket.com/albums/o...0/Untitled.jpg

Re: I need some tail light wiring help, please....
 

I would only add that MAKE SURE you have a great ground. If one ground does not have a good connection, it messes with the entire system. Check them all, and be sure your tail light areas are not painted over where the housings touch the body.

Re: I need some tail light wiring help, please....
 

Here's where I got mine from. fast shippers also. here's a link to their page.
Part numbers 52-623 and 52-662 hope this helps.

http://www.classicparts.com/Wiring-H...oducts/205/3/0

Re: I need some tail light wiring help, please....
 

Thanks for the schematic... I will print if off and see if I can make sense of this. It looks like I have the yellow and green wires, but the brown wires are black and black/ yellow on the plug that is being used. Maybe a different plug-harness than the stock one has been put in. I will try to wire it up and use the black and black/yellow wire as browns per the schematic and see what happens.

Re: I need some tail light wiring help, please....
 

YeLlow is left turn
gReen is right turn
Brown or black is park /tail
the other one is prolly back up lights usually lt green
these are the SAE /stock rear light colors using them make later trouble shooting easier
As posted above sounds like a ground issue

Re: I need some tail light wiring help, please....
 

Got all the wires traced out today, found were each was supposed to go and was able to get it working correctly. It is true that good grounds are very important on this type of system. I found that the lights were just a little dim just using the buckets as a ground themselves. So, I ran additional wire connected to each bucket screw and made one good, solid connection on the frame. Brightened up the bulbs considerably. Thanks to all for the help. She'll be up and running soon. Pics to follow...

Re: I need some tail light wiring help, please....
 

Try here:

www.classicparts.com
www.bowtiebits.com
www.oldchevytrucks.com
www.truckandcarshop.com

I have purchased wiring harnesses from LMC Truck on several occassions, over the counter, without waiting for backordering.

Re: I need some tail light wiring help, please....
 

The short answer is yes. The ground side must be just as efficient as the power side or the device will not operate at full capacity. Grounding all the lamp buckets with wire to a common ground, instead of relying on brackets (which may be loose, rusty, or painted) will eliminate many random electrical problems in the future.

Re: I need some tail light wiring help, please....
 

I just received the wiring harness (from classic parts) from the firewall to the rear for my tail lights and noticed that there is a 3 prong plug that plugs into the firewall and a single that I don't have a plug for. Is the single a ground?

Re: I need some tail light wiring help, please....
 

Nothing is grounded in the harness, only at the light buckets. You should only need three wires to operate the taillights. Left, right, and brake. The extra wire may be for back-up lights if you have them. The only other wire is a short pigtail off the drivers side tail that is for the license plate; connected to the running lights.

Re: I need some tail light wiring help, please....
 

I just received the wiring harness (from classic parts) from the firewall to the rear for my tail lights and noticed that there is a 3 prong plug that plugs into the firewall and a single that I don't have a plug for. Is the single a ground?
__________________

I'm sure that wire is for your backup lights, if you have them.

Re: I need some tail light wiring help, please....
 

I added a grounding block to the rear and front of my gmc, soldered a ground wire to every light housing then grounded it to the block. Bright lights no mysterious dim light............and then searching around for a good ground. It is worth the time and the money. Kieth


Attachment 824272

Re: I need some tail light wiring help, please....
 

thanks for the info guys.....I'll see what happens when I get the battery hooked up.

Re: I need some tail light wiring help, please....
 

Re: I need some tail light wiring help, please....
 

I know this is a very old thread...but seems to be maybe a issue we all can have,
I have a 62 C10 I recently purchased.
previous owner had installed new LED hood markers an taillights.
Hood markers are good n bright an work as should. However the taillights had worked when purchased but the driver side was a bit dimmer. figured ground but hadn't got to check.
i had been wanting to work on a headlight issue he told me of being the headlamps were very dim an drivers was bright an passenger barely illuminated.
so... when i went to pull the truck outside i noticed i hadn't seen my brake lights light up as i pulled from the garage.
i turned my headlights switch on an surprise i had NO taillights /brake lights or rear turn signals.
So... i checked fuse...GOOD.
Checked wire connections GOOD
However not sure if i have power yet as im still diagnosing this. Need Some Guidance
So Where do i start at ...when it worked fine before..
Could A Faulty Headlight switch be Causing all my issues? with faulty headlights an now NO rear lights at all???

Re: I need some tail light wiring help, please....
 

As is often the case with this old stuff. You may be chasing multiple faults. However your brake lights are independent of the head light switch. They do run through the turn signal switch. I always check power up the column and back.
The switch is like the central nervous system of indicator lights.

Re: I need some tail light wiring help, please....
 

Time to get a voltmeter (DVM), wiring diagram and work on understanding how things work. Voltage is typically measured to ground with everything connected.
Learn Ohm's Law (simple) and the relationships between coltage, current and resistance.
Turn/brake lights are different filaments than running lights. Always keep in mind that the exact same current that flows into a load from the battery/alt has to flow back to the source via the ground. One of the headache reducing things to do would be go through and fix all the grounds.

https://www.google.com/search?client...wiring+diagram

Re: I need some tail light wiring help, please....
 

Are the tail light buckets aluminum or stainless.? just curious how to solder on them

Re: I need some tail light wiring help, please....
 

Neither. Steel as they will rust.

Re: I need some tail light wiring help, please....
 

Awesome..
Well fixed my front headlights over the week...
Cleaned up ALL connections an made new ground wire...WALA bright headlights.:metal:

Re: I need some tail light wiring help, please....
 

New taillight harness came today finally from classic parts along with new tail light buckets.
going to run all new wire harnesses.. an ground these tail light bucket housings separately.
I have been digging into this issue some this week an there may be a issue with the aftermarket turn-signal assembly previously installed by old owner. As well as the wire connection issues. Stay tuned guys..i appreciate all the inputs

Re: I need some tail light wiring help, please....
 

So I finally got to install my new tail light buckets. With new ground wires attached an to frame rails.
Connected my new harness for taillights.
So I was curious to see how the taillights would be .
Yet still having to install the harness to the firewall.
So I plugged in the new taillights harness to existing factory harness.
An I have good bright running an brake.
But now my signals flash like hazards.

Re: I need some tail light wiring help, please....
 

Flash like hazards because when you turn on signal both flash?
If so check signal switch.

Flashing like hazards because of increased speed?
With a bimetal flasher more load forces the flasher to break circuit faster.
This is why you need a heavy duty flasher for towing a trailer. More blinkers.

A weak flasher will have the same effect. May be time for a new one. Or something could be placing more load in the circuit but not as likely. If you have other old cars rob a flasher to substitute.

Reminds me of 80's era japanese cars. For one they had yellow blinkers. That was bothersome enough. But after a few years they would flash at two times speed.
Japanese cars and high speed yellow blinkers.

That story reminds me of two others. What I note today during commuting.
A very disproportionate number of toyota prius with no tail lights. With second place going to Tesla. Why does the electric car have no tail lights?

Which reminds me finally of the fact that every time I see this their dash lights are on. In previous years the dash lights were on the tail light circuit and we were taught that if you had no dash lights. Stop and check your tail lights.
Probably too much info for the modern peanut.

Re: I need some tail light wiring help, please....
 

It has a LED flasher.
An yes the turn signal flashes together like a hazard signal.
The speed isn't the issue.
Its that now when I select right or left turn.
It flashes both sides together.

Hit the brake an they stop.
Without turn signal on.
Stop an taillights work correctly.

Re: I need some tail light wiring help, please....
 

I think I have a harness issue.
I just got one from ecklers.
Maybe its wired wrong.

Re: I need some tail light wiring help, please....
 

ok so...
I rechecked my connections again from front going to back.... i havent changed anything PO has did.
Now when i go to the plug coming from firewall to rear taillight harness i test turn tail an stop functions an all is good.
I plug in my new harness from Eklers an go test the taillight functions an there is
Issues..
1 - Turn signals left an right will flash as a hazard type flash.
2 - taillights only both nice an bright (work as should)
3- brake lights only nice an bright.(work as should)
4 - turn signal left an right both flash together.... an when u hit the brake they both stop an stay illuminated.
Pulled out bulbs an check plug socket...i get same as above off my test light.
I unplug my new harness an re-plug in my old original harness an test all functions an everything appears to work as should.
The reason i swapped old harness out cause it had some wire damage at the socket area an had been previously had some wire repairs in its day.
Could I have Gotten A Bad Harness?
Ill be contacting Eklers before i cut into the new harness wires.

Re: I need some tail light wiring help, please....
 

Well it all boils down to a faulty new harness plug.
Hopefully I get a discount on next parts I may need from Eklers.
Had to cut off new harness plug and rewire my old plug to the new harness....
I now finally have perfect working taillights turn signal an braking light function....