Trailer Wiring

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ETM
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Trailer Wiring

ETM
Having some Issues with it comes with Wiring up some trailer Light on my Old Truck, Not sure you would have any Ideas. The Wiring on my Tuck is an mess and is cobbled together by an Local Shad Tree guy. So all of the Wires out side of the cab are not the correct colour but I digress. So I've Wired in my Flat 4 plug as best as I can but having some issue with having the Headlights on and using my Brake lights. With my head lights off all is good have turn signals and Brake lights but with my Lights are on I no longer have brake light, Thinking of wiring my running lights to my plate light that I just fixed after this winter with it being broken. Any extra Thoughts or Ideas is gratefully appreciated.

Quote on Quote picture of Rear Bumper.


Sorry moved post over
1981 F100 - One Owner 300 I6 - 3 on the Tree
1983 F250 - Mud Truck/ Project 6.9idi / 4spd / 4x4 *Part out Keeping Trans and Steering*

Ontario, Canada
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Re: Trailer Wiring

Gary Lewis
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I think you have a ground problem.  With the headlights off they provide a ground to the brake lights.  But with them on they no long provide a ground.  I can't tell you where the bad ground is, but I'd bet that you have a ground problem, and probably at the tail lights.

On the early trucks, like yours, there was a ground wired from the light socket to ground on the bed inside the tail light opening.  But if your bed isn't grounded well then that could be a problem.
Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker in front & 10.25 Spicer/Trutrac in bac, & EEC-V MAF/SEFI
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Re: Trailer Wiring

FuzzFace2
I also think it is a ground issue.
As for the truck rear light ground others have posted it is not in the light housing, my parts truck was in the housing.
They say the ground wire picks up both rear lights and goes all the way up front and is tied into other grounds on the firewall behind the radio, so they say.

How did you tie in the flat plug?
You should have a wire to:
The left turn / brake light.
The right turn / brake light.
The running lights - this can tie into either light or the plate light like you posted.
The 4th wire in the plug, think white, is the trailer ground and can go to any clean place on the frame.

Now why this happened after the plug install is beyond me. I think you had this problem before and just seen it now.
https://www.etrailer.com/
Have a lot of good information on how to wire up for a trailer to parts to make this happen.
I have used them for different trailer parts when needed
Dave ----
81 F100 flare side 300 six/T18 project
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck
http://cars.grantskingdom1.com/index.php/1981-Ford-F100
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Re: Trailer Wiring

Gary Lewis
Administrator
Dave - I'll have to check when the change was made in the grounds, but I'm pretty sure it was for '85.  Prior to that there was a ground wire in the tail light opening.  After that the grounds were collected into one wire that went all the way back into the cab.
Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker in front & 10.25 Spicer/Trutrac in bac, & EEC-V MAF/SEFI
ETM
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Re: Trailer Wiring

ETM
In reply to this post by FuzzFace2
FuzzFace2 wrote
I also think it is a ground issue.
As for the truck rear light ground others have posted it is not in the light housing, my parts truck was in the housing.
They say the ground wire picks up both rear lights and goes all the way up front and is tied into other grounds on the firewall behind the radio, so they say.

How did you tie in the flat plug?
You should have a wire to:
The left turn / brake light.
The right turn / brake light.
The running lights - this can tie into either light or the plate light like you posted.
The 4th wire in the plug, think white, is the trailer ground and can go to any clean place on the frame.

Now why this happened after the plug install is beyond me. I think you had this problem before and just seen it now.
https://www.etrailer.com/
Have a lot of good information on how to wire up for a trailer to parts to make this happen.
I have used them for different trailer parts when needed
Dave ----
So it is wired into the
Left Brake and Turn
Right Brake and Turn
Then the Running is wired into the Right Running light
^ Thinking of changing this to the plate light and see if this helps.
Grounded to the bed but may change it to the Frame
Been raining non stop.
1981 F100 - One Owner 300 I6 - 3 on the Tree
1983 F250 - Mud Truck/ Project 6.9idi / 4spd / 4x4 *Part out Keeping Trans and Steering*

Ontario, Canada
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Re: Trailer Wiring

Steve83
In reply to this post by ETM
This gives the old Ford colors, the revised Ford colors, the later standard vehicle colors, the standard trailer colors, and the standard trailer connector colors:



If the headlights affect the taillights, it's likely because the taillights are not grounded.  The easiest way to fix them is to run their black wire all the way to the engine block, frame, or body ground (so it's in contact with the big negative cable).
Walk softly and carry a BIG SIX!!!
https://www.supermotors.net/registry/2742#album
Memphis, TN, USA, Earth, Milky Way
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Re: Trailer Wiring

FuzzFace2
In reply to this post by ETM
ETM wrote
FuzzFace2 wrote
I also think it is a ground issue.
As for the truck rear light ground others have posted it is not in the light housing, my parts truck was in the housing.
They say the ground wire picks up both rear lights and goes all the way up front and is tied into other grounds on the firewall behind the radio, so they say.

How did you tie in the flat plug?
You should have a wire to:
The left turn / brake light.
The right turn / brake light.
The running lights - this can tie into either light or the plate light like you posted.
The 4th wire in the plug, think white, is the trailer ground and can go to any clean place on the frame.

Now why this happened after the plug install is beyond me. I think you had this problem before and just seen it now.
https://www.etrailer.com/
Have a lot of good information on how to wire up for a trailer to parts to make this happen.
I have used them for different trailer parts when needed
Dave ----
So it is wired into the
Left Brake and Turn
Right Brake and Turn
Then the Running is wired into the Right Running light
^ Thinking of changing this to the plate light and see if this helps.
Grounded to the bed but may change it to the Frame
Been raining non stop.
Sorry not getting back sooner.
Yep that is how it should be done.
I cant see picking up running lights from the plate light would help the issue but if it makes you happy then go for it.

BTW there is a Tee trailer harness, Etrailer or others, that you unplug the trucks tail lights from the rear harness plug in the trailer harness to the rear harness and the tail lights to the trailer harness.
1 of my trucks came with one and will be using it on mine when I get that far.
Dave ----
81 F100 flare side 300 six/T18 project
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck
http://cars.grantskingdom1.com/index.php/1981-Ford-F100
ETM
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Re: Trailer Wiring

ETM
FuzzFace2 wrote
BTW there is a Tee trailer harness, Etrailer or others, that you unplug the trucks tail lights from the rear harness plug in the trailer harness to the rear harness and the tail lights to the trailer harness.
1 of my trucks came with one and will be using it on mine when I get that far.
Dave ----
Sorry about the Delay, The Wiring in this truck is an mess other then the Interior Was an real Shad Tree Job, it works but lots of wires just taped together, I like to Solder and shrink tube it. Will have to Go over it later. Tested will an Test Light Seems to work fine will new more when the U-Haul Trailer is Hitched up. Thanks for all of the help.  
1981 F100 - One Owner 300 I6 - 3 on the Tree
1983 F250 - Mud Truck/ Project 6.9idi / 4spd / 4x4 *Part out Keeping Trans and Steering*

Ontario, Canada