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Old 09-02-2014, 05:44 PM   #1
davepl
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No-cut trailer wiring?

Does anyone make a harness that would allow me to add camper wiring, including an electronic brake controller (which I have) without cutting into my brand new harnesses?

I found one in the Brother's catalog that appears to go in-line at the extension connector under the bed to the tail lights, but I think that'd only work for the boat setups (hydraulic trailer brake) and not with a brake controller.

The setup installed in my truck when I got it was completely a hack job. I mean they used a torch to blow a 2" jagged hole through the frame to run the wires and all the connections were "twist and tape it" jobs. I want to do it right, and to not hack up my harness.

Thanks!
Dave
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Old 09-02-2014, 08:21 PM   #2
Mike C
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Re: No-cut trailer wiring?

If you are going to have electric brakes, you must add that circuit along with the brake control, heavy 10ga wire, and circuit breakers. You can get an extension harness that plugs in between the front and rear factory harnesses, then you can modify that to hook up the brake, turn and tail lights. I did same thing on my '70 GMC 3/4 ton.
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Old 09-02-2014, 09:45 PM   #3
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Re: No-cut trailer wiring?

Are you running a 5 pin connector or larger seven pin rv plug? If all you need is electric brakes, all you need is a 5 pin. 7 pin is only if you also need a charging circuit. No one I know of makes a plug in 5 pin, but why couldn't you use the 4 pin adapter, clip the end, and add the wire from your brake controller to the four wires and terminate them in a 5 pin connector? You would still need to tap into the brake light circuit, and get power for the controller from the fuse box.
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Old 09-02-2014, 10:19 PM   #4
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Re: No-cut trailer wiring?

This site might have something you are looking for:

http://www.hopkinstowingsolutions.co...ing-harnesses/
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Old 09-02-2014, 10:20 PM   #5
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Re: No-cut trailer wiring?

I recently wired my truck for trailer brakes. I followed the instructions here and it turned out pretty good and everything works like it should.

http://67-72chevytrucks.com/vboard/s...d.php?t=513440
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Old 09-02-2014, 10:28 PM   #6
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Re: No-cut trailer wiring?

If you still have the factory camper wiring, the solution should be easy as you can just run it to the back, add a brake wire and connect all wires to a 7-pin connector. That would include ground, taillights, brake lights, turn signals, backup lights, 12volt hot and brakes.

If you don't have the camper harness, This (http://www.hopkinstowingsolutions.co...ban_73-84.html) plugs between your front and rear harnesses and should take care of your basic 4 wire hookup for ground, taillights, turn signals and brake lights without splicing. Then cut off the 4-way trailer plug and get a 5 or 7 pin connector that matches the one on your trailer. Run those wires plus a wire for the brake controller, a 12 volt hot from the auxiliary battery (if desired) protected by a 30(?) amp breaker. If you want backup lights you'll need to tap into that line at the rear of the truck. The backup lights and hot wire would require the 7-pin connector. If you are running wires it would be a good idea to run a heavier ground in place of (or in addition to) the one in the Hopkins connector.

By the way, my factory camper harness was also run through a jagged hole in the frame , but it is only one inch in diameter. I wouldn't be so hasty to assume yours was a P.O. hack job. Below is a picture of my factory camper harness coming through the frame. I assume the quality of the hole and diameter would have varied depending on the day, plant and worker.
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Last edited by FirstOwner69; 09-02-2014 at 10:36 PM.
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Old 09-03-2014, 07:58 AM   #7
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Re: No-cut trailer wiring?

Quote:
Originally Posted by FirstOwner69 View Post
By the way, my factory camper harness was also run through a jagged hole in the frame , but it is only one inch in diameter. I wouldn't be so hasty to assume yours was a P.O. hack job. Below is a picture of my factory camper harness coming through the frame. I assume the quality of the hole and diameter would have varied depending on the day, plant and worker.
Wow-You'd think a grommet would have been added at least or they could've made another bulkhead connector like for the taillight harness. But if it lasted 40+ years....
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1988 GMC Sierra, 305, Auto
1984 Jeep Grand Wagoneer, 360 V8
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Stuff I wish I still had:
2013 Toyota Matrix [RIP]
1967 GMC 910 Fleetside, 283 V8 [1st Love-SOLD]
1987 Jeep Cherokee Laredo 4X4, 4.0 I-6 [SOLD}
1994 Chevrolet Caprice Classic, 5.7LV8 [SOLD]
1995 Chevrolet Astro AWD, 4.3L V6 (RIP)
1998 Chevrolet Suburban 4x4, 5.7L V8 [SOLD]
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Old 09-03-2014, 01:03 PM   #8
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Re: No-cut trailer wiring?

We sell a harness made by M&H wiring that plugs directly into your taillight intermediate harness and into your taillight harness. It has a pig tail that comes out of the end where it plugs into the intermediate harness to wire the plug for your trailer. It has the factory rubber bulkhead connectors so your factory wiring plugs into it, no cutting required. $40.00 WES
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Old 09-03-2014, 01:30 PM   #9
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Re: No-cut trailer wiring?

Just finished up with the same thing. Mounted 2 breakers (30 & 40amp) near the battery, then ran the 40 all the way to the back, and the 30 to the brake controller. Drilled a small hole below the bulkhead connector for the power to the controller, then the brake lead from the controller. Then ran the 40 amp lead (auxiliary) and the brake lead tie wrapped with the existing wiring. Overall not a real hard project, just amazing how much wire you need, and the cost, if you do it right. I cut the connector off the brake controller, then added spade terminals, so i can disconnect when it is not needed. I also added a terminal strip, and some covers so i did not have a bunch of exposed terminals. Also i had the 4 pin connector already, so the harness for the 7 pin that i got plugged right into that. All i had to do was connect a ground, auxiliary, and controller to the harness. So from standpoint the only cutting i had to do was the line from the brake switch.
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Old 09-03-2014, 01:54 PM   #10
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Re: No-cut trailer wiring?

Sanity check my understanding:

If I use the harness from Wes that gives me all of the trailer LIGHTS but without brakes or charging.

I then add three runs:

1) Heavy gauge from bat to brake controller
2) Heavy gauge from brake controller to trailer brake pin in 7-pin connector
3) Heavy gauge from bat to trailer pin for camper charging
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Old 09-03-2014, 03:01 PM   #11
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Re: No-cut trailer wiring?

That sounds correct. However, no brake controller I've installed required "heavy gauge" wire. I'd follow the manufacturer's instructions for the brake controller. I don't think you need anything heavier than 14 gauge for that. For the 12 volt hot for charging, I'd run 12 or 10 gauge. I think GM included 12 gauge for the charging wire... and still does today. Of course, there would be nothing wrong with 10 but it gets pretty difficult to get that all into the 7-pin connector housing.
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Old 09-03-2014, 03:10 PM   #12
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Re: No-cut trailer wiring?

Quote:
Originally Posted by Classic Heartbeat View Post
We sell a harness made by M&H wiring that plugs directly into your taillight intermediate harness and into your taillight harness. It has a pig tail that comes out of the end where it plugs into the intermediate harness to wire the plug for your trailer. It has the factory rubber bulkhead connectors so your factory wiring plugs into it, no cutting required. $40.00 WES
How much to ship one ( possibly 2) of those to me in Canada? S0K2T0. Thanks, Rod.
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Old 09-03-2014, 06:03 PM   #13
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Re: No-cut trailer wiring?

Looks like about $20.00 in a small flat rate box. WES
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Old 07-06-2016, 02:35 PM   #14
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Re: No-cut trailer wiring?

So if I get the pigtail from Wes, I have 7 pins:

- 12V POWER - From AUX battery I think is best because I have that option
- GROUND - Ground
- Tail & Running - From pigtail
- Reverse Lights - From pigtail
- Right turn and stop - From pigtail
- Left Turn and stop - from Pigtail
- Brake output - From brake controller

Sound right?

I wish there was a retro looking brake controller that looked period correct that I trusted... that'd be cool.
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Old 07-06-2016, 04:01 PM   #15
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Re: No-cut trailer wiring?

Quote:
Originally Posted by davepl View Post
So if I get the pigtail from Wes, I have 7 pins:

- 12V POWER - From AUX battery I think is best because I have that option
- GROUND - Ground
- Tail & Running - From pigtail
- Reverse Lights - From pigtail
- Right turn and stop - From pigtail
- Left Turn and stop - from Pigtail
- Brake output - From brake controller

Sound right?

I wish there was a retro looking brake controller that looked period correct that I trusted... that'd be cool.
This link should help you sort out the wiring connections.
https://www.etrailer.com/question-363.html

If you had a retro looking controller it'd probably tap into the brake hydraulic system.
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