How to wire a 4 or 7 pin trailer connector and backup camera without splicing/cutting factory harness. (1 Viewer)

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Oct 9, 2023
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I thought I'd share how I wired my trailer connector and backup camera because I haven't seen anyone else use the factory plugs to their fullest potential. I did this on my HDJ81 but this will work for any 80 series.

What you'll need for a flat 4 connector w/ backup camera:
Optional parts for wiring 7 blade connector:

Located at the back of the spare tire carrier area there are two sets of plugs. A single large one in the center that is used to connect the OEM secondary fuel tank, and on the right-hand side of the vehicle is a bundle of 3 plugs that in my case were all taped together. Here I've removed the electrical tape and disconnected the two that are plugged together. Clean these plugs and then pack with terminal grease supplied with the wire harness.

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Others have used this Tekonsha wiring harness to add/replace a flat 4 trailer connector, however, there is an additional terminal in one of the factory plugs that goes unused. That extra black and red wire on the factory 3 terminal plug is a reverse signal wire. The Tekonsha wire harness just has a blank in this position. By adding the missing terminal to the Tekonsha harness we can pull power from the reverse light circuit without cutting into the factory harness.

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Adding the reverse light terminal to the Tekonsha harness:

Crimp the flat/blade terminal onto a red 16ga wire and heat shrink. For a 7-blade trailer connector, also crimp the purple wire (cut to length) from the Hopkins harness into this same terminal as I have done below. This red wire will be run into the rear quarter panel and connected to the camera power wire and the convenience wire in the camera extension cable later.

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Insert this terminal into the blank location on the Tekonsha 3 terminal plug. If you are only using the flat 4 connector on the Tekonsha harness skip the following section.
 
Wiring a 7-blade connector:

Cut off the flat 4 plug and the majority of the wiring from the Tekonsha harness leaving 4-5 inches of wire protruding from the adapter box. Strip these four wires.

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Separate the brown/black, white, yellow, and green wires from the Hopkins harness and cut to length necessary for your application. Strip these four wires.

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Slide some marine heat shrink over the Hopkins harness wires you have just cut and stripped. Then match the colors from each harness and solder the wires together.

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Slide the heat shrink over your joints and blast them with a head gun or lighter.

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Wrap this new section of joined harrness in a wire loom and tape in place.

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The remaining blue wire will be connected to your trailer brake controller (I will be connecting this redarc Tow-pro unit at a later date). The remaining red wire will be connected to aux power (I will be connecting this directly to my battery to have constant power to the trailer).

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Installing the harness and camera:

You should now have a custom harness that looks something like this (or with just the Tekonsha flat 4 connector). I have added wire loom to both sides of the adapter box to keep it tidy and protect the wires from damage.

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Mount your camera as desired. I am flush mounting mine in a 4x4 labs bumper.

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Route your camera wire towards the right-hand side of the vehicle.

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Plug your custom harness into the factory plugs as shown. Route your red wire and camera wire into the quarter panel through the existing wire harness plug seen on the left. (Optionally, also route your aux and trailer brake wires through this same plug.)

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Secure the remaining harness and route your trailer plug as desired. I have my 7-blade connector harness plugged into the Hopkins multi-two connector mounted into a 4x4 labs bumper.

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With the harness in place and secured, connect the camera extension cable to the camera wire. Solder all three red wires together (red wire from added terminal, red power wire to camera, and red convenience wire in extension cable) as shown. Ground the black wire from the camera (I grounded this to a bolt from the factory sub).

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Tidy up any extra/loose wire and route your camera extension wire forward under/behind the trim as you would with any other backup camera setup.

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Connect your backup camera to your head unit along with the red trigger wire. Now you have a functional trailer connector and backup camera without any cutting/splicing of the factory harness. Let me know if you have any ideas on how to improve this setup!

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Good clean work and will prove useful to many.
 
Genius!
 
hey there kendgray, big thanks for this write up.
Saved some time to connect to that wiring plug for the reverse signal.
Reverse camera works perfectly from that connection.

I couldn't tell what colour the wires were, but positive reverse light was the one with arrow below.
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