How Do I run a trailer light harness to the back of my truck?

bubbas91lariat · 08-02-2007, 02:39 PM

I have a 91 f150 and when i got it from my dad, it didnt have a lighting harness on it. We are thinking of buying a new trailer and we dont want to get pulled over for not having lights. How do i run a harness wire from the fuse/relay box in the hood?

mrjohnwayne · 08-02-2007, 02:43 PM

there should be a connector for the rear tail lights at the back of the bed underneath. most parts houses sell the connector that plugs in the factory harness so there are no cut wires.

mudseeker · 08-02-2007, 02:45 PM

i just spliced in to my tail lights on my GMC. actually i spent the extra 15 dollars and bought an adapter so i didn't have to cut the tail light wires under the bed.

bubbas91lariat · 08-02-2007, 05:18 PM

there is a plug for trailer lights in the fuse/relay box under the hood but i cant figure out how to hook anything up to it. and i dont really know how to splice into the taillights.

crabtruck · 08-02-2007, 05:57 PM

You should be able to snag a plug from a U-Haul place or any other that rents trailers.
On the back of the package is a wiring diagram.
Whatever you touch in wires on that old a truck be sure to seal or tape over, even just pulling apart plugs and replugging.
Insulation and orig sealants get brittle after a while. If you don't use extra protection, before winter is done you may have no lights on trailer and none on truck too. Moisture tends to crawl up under insulation and corode the wire invisibly. And if you're getting freezes that breaks strands too.

bubbas91lariat · 08-02-2007, 06:21 PM

Thanks. Ill see if tht wrks.

390FE · 08-03-2007, 08:09 AM

The plug johnwane was talking about is usually on the rear drivers side near the tail light. The wires run back the length of the truck to the rear. There is a seperate wire harness going from the end of those wires to the tail lights. The connector it a T connector with male and f-male on the top of the T and a length of wire with the 4 way flat off the bottom of the T.

Unplug and replug. No thought no wiring and a lot faster, unless the stock plug dosen't want to come unpluged.

bubbas91lariat · 08-03-2007, 05:13 PM

I found a little plug that ties into the taillights. Its shaped like a circle. Is that the one yur talkin about John?

mrjohnwayne · 08-03-2007, 05:46 PM

If I remember it is a circular or square plug depending on year. If you can snap a picture of it it would help.

bubbas91lariat · 08-03-2007, 05:56 PM

ill see wut i can do.

08-02-2007, 02:39 PM	#1
bubbas91lariat Senior Member Join Date: Dec 2005 Location: Elberton,GA Posts: 825	How Do I run a trailer light harness to the back of my truck? I have a 91 f150 and when i got it from my dad, it didnt have a lighting harness on it. We are thinking of buying a new trailer and we dont want to get pulled over for not having lights. How do i run a harness wire from the fuse/relay box in the hood? __________________ IF YOU AINT FIRST YOUR LAST!!!

08-02-2007, 02:43 PM	#2
mrjohnwayne Moderator Join Date: Apr 2005 Location: Texas Posts: 3,114	there should be a connector for the rear tail lights at the back of the bed underneath. most parts houses sell the connector that plugs in the factory harness so there are no cut wires. __________________ John Wayne 2000 F-350 7.3L Powerstroke 4x4

08-02-2007, 02:45 PM	#3
mudseeker mod-o-tator Join Date: Feb 2006 Location: michigan Posts: 4,059	i just spliced in to my tail lights on my GMC. actually i spent the extra 15 dollars and bought an adapter so i didn't have to cut the tail light wires under the bed. __________________ member map add yourself

08-02-2007, 05:18 PM	#4
bubbas91lariat Senior Member Join Date: Dec 2005 Location: Elberton,GA Posts: 825	there is a plug for trailer lights in the fuse/relay box under the hood but i cant figure out how to hook anything up to it. and i dont really know how to splice into the taillights. __________________ IF YOU AINT FIRST YOUR LAST!!!

08-02-2007, 06:21 PM	#6
bubbas91lariat Senior Member Join Date: Dec 2005 Location: Elberton,GA Posts: 825	Thanks. Ill see if tht wrks. __________________ IF YOU AINT FIRST YOUR LAST!!!

08-02-2007, 05:57 PM	#5
crabtruck Senior Member Join Date: Jul 2007 Posts: 1,464	You should be able to snag a plug from a U-Haul place or any other that rents trailers. On the back of the package is a wiring diagram. Whatever you touch in wires on that old a truck be sure to seal or tape over, even just pulling apart plugs and replugging. Insulation and orig sealants get brittle after a while. If you don't use extra protection, before winter is done you may have no lights on trailer and none on truck too. Moisture tends to crawl up under insulation and corode the wire invisibly. And if you're getting freezes that breaks strands too.

08-03-2007, 08:09 AM	#7
390FE Senior Member Join Date: Sep 2005 Location: S. NH Posts: 336	The plug johnwane was talking about is usually on the rear drivers side near the tail light. The wires run back the length of the truck to the rear. There is a seperate wire harness going from the end of those wires to the tail lights. The connector it a T connector with male and f-male on the top of the T and a length of wire with the 4 way flat off the bottom of the T. Unplug and replug. No thought no wiring and a lot faster, unless the stock plug dosen't want to come unpluged. __________________ 87 Toyota 4x4 -- 72 F250 -- 68 F250 -- A Ford kah -- New to Family is 07 Ranger FX4

08-03-2007, 05:13 PM	#8
bubbas91lariat Senior Member Join Date: Dec 2005 Location: Elberton,GA Posts: 825	I found a little plug that ties into the taillights. Its shaped like a circle. Is that the one yur talkin about John? __________________ IF YOU AINT FIRST YOUR LAST!!!

08-03-2007, 05:46 PM	#9
mrjohnwayne Moderator Join Date: Apr 2005 Location: Texas Posts: 3,114	If I remember it is a circular or square plug depending on year. If you can snap a picture of it it would help. __________________ John Wayne 2000 F-350 7.3L Powerstroke 4x4

08-03-2007, 05:56 PM	#10
bubbas91lariat Senior Member Join Date: Dec 2005 Location: Elberton,GA Posts: 825	ill see wut i can do. __________________ IF YOU AINT FIRST YOUR LAST!!!

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