JT trailer wiring harness dissection

[GtownTX]

Ok, I've looked at many wiring diagrams and I just keep not finding one which has all the colors represented here mapped to the right circuit. Interested to locate the tail/license plate lead for the trailer. Can someone point me to the corresponding diagram? Thank you!

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[mojaveron]

 

[Beemer533]

I needed to get brake and signal wiring, but I am avoiding cutting into my factory harnesses at all costs.

I just got this t harness which plugs into the rear of the 7 pin. It gets you left/brake, right/brake, tail, reverse.

I just cut off the 5 pin and spliced my wiring onto that.

CURT 56584 Replacement Vehicle-Side Custom USCAR 5-Pin Trailer Wiring Harness , Black https://a.co/d/2mfheIJ

 

[ShadowsPapa]

Ok, I've looked at many wiring diagrams and I just keep not finding one which has all the colors represented here mapped to the right circuit. Interested to locate the tail/license plate lead for the trailer. Can someone point me to the corresponding diagram? Thank you!

Already a response I see, but gee, this is simple because they are all the same - just Google it and get thousands of hits.

 

[ShadowsPapa]

I needed to get brake and signal wiring, but I am avoiding cutting into my factory harnesses at all costs.

I just got this t harness which plugs into the rear of the 7 pin. It gets you left/brake, right/brake, tail, reverse.

I just cut off the 5 pin and spliced my wiring onto that.

CURT 56584 Replacement Vehicle-Side Custom USCAR 5-Pin Trailer Wiring Harness , Black https://a.co/d/2mfheIJ

Several have done that to get power to aux backup lights instead of tapping into something else.

 

[Beemer533]

Several have done that to get power to aux backup lights instead of tapping into something else.

Yeah, it works really well for sure. I just can't stand cutting into factory harnesses, especially up here in the salt capital

 

[ShadowsPapa]

I just can't stand cutting into factory harnesses, especially up here in the salt capital

I hear ya and agree........ and then you know what the white stuff here is LOL

 

[Beemer533]

I hear ya and agree........ and then you know what the white stuff here is LOL

All too familiar lol. I think most years we get more salt than precipitation.

Makes everything nasty..

 

[bd100]

In case you ever do have to splice into a wire in the salt zone, one way which worked for me and lasted for decades afterwards even after numerous winters:

- Cut the insulation around the wire in the area you want to splice into. Don't cut the wire, just the insulation around it.
- Using a pointed pick, form a hole in the middle of the strand, some wires going past the hole on each side.
- Place the end of the new branch into that hole and wrap the copper around a few times.
- Position the branch to rest next to the original wire.
- Zip tie the branch to the original wire, for strain relief of the solder joint.
- Solder.
- Liquid electrical tape the joint. Good against salt.
- Shrink wrap or electrical tape next.
- Waterproof tape over it all.

It's a big sloppy mess but it lasts "forever"-ish.

 

[Lost1wing]

They make some pretty good heat shrink splices and tee's. I have used them on other projects but not on the Jeep. You get to see how well they work when you error and need to replace the splice. Even though I am salt free, my option would be the plug in trailer connector from Curt and splice in from there. I'm not a fan of cutting into a factory harness either if I don't have to.

 

[Rockabillyroy]

I made my own for my bumper lights. Here is one that has some already added.

https://www.amazon.com/dp/B0B19FZ3JC/

 

[GtownTX]

Thank you all. On the color coded diagram above, I looked at that one a few times and just not seeing the color alignment that I was hoping for vs the one in the harness itself. I'm aligned this isn't necessarily the most awesome place to perform a splice but good news is I'm not in a snowy/icy climate and will ensure I protect it well.

 

[ShadowsPapa]

In case you ever do have to splice into a wire in the salt zone, one way which worked for me and lasted for decades afterwards even after numerous winters:

- Cut the insulation around the wire in the area you want to splice into. Don't cut the wire, just the insulation around it.
- Using a pointed pick, form a hole in the middle of the strand, some wires going past the hole on each side.
- Place the end of the new branch into that hole and wrap the copper around a few times.
- Position the branch to rest next to the original wire.
- Zip tie the branch to the original wire, for strain relief of the solder joint.
- Solder.
- Liquid electrical tape the joint. Good against salt.
- Shrink wrap or electrical tape next.
- Waterproof tape over it all.

It's a big sloppy mess but it lasts "forever"-ish.

Why get so messy?
Having worked in an electronics engineering company and watching how they did their wiring for atmospheres at petrol drilling sites, pumping stations, pipelines and other nasty places, and then going on and making wiring harnesses for automotive restoration, it's really simple.
Electric tape is short term, especially when exposed to elements. It will fail.
I've had liquid tape fail as well - it's very dependent on the type of insulation used on the wire. It just won't last against certain wire insulations.

Do it like the pros - look at wiring harnesses that come with equipment like the RSE power steps or other fun stuff. They use either a butt splice crimp or solder the wires and use a sealed heat shrink tube over it. That's all that is needed.

Extremely simple process:
DO cut the wire, use either a factory type crimp connection, or solder, then use a marine type heat shrink.
Neat and a forever joint.

It's how I did a lot of the wiring when I merged the Jeep PDC and PCM into my car's original systems.

Here's one explanation from Douglas Dynamics/Western Snow Plow -

You can use solder only after twisting the wires together and skip the crimp splice, or use a quality splice connector.

In any case, a good water-proof heat shrink will seal it proper. If you are paranoid after that, you can use a type of tape that is rubberized and sticks to itself. Stretch it around the joint like you would electric tape, but use a bit of stretch in the process of wrapping. Because it's rubbery it forms snug around nooks and crannies and forms a bond to itself that's so good after a few hours you can't pull it apart without cutting it or ripping it to shreds.
It's neat and very sealed, although the marine type heat shrink with the glue inside is all that's really needed.

I'm all about neat in wiring. I want it to look factory when done, not hacked. People look at the engine swap in my car and believe it came that way.

 

[bd100]

Why get so messy?

Was always concerned that the heat shrink glue might not be enough to fill the gap between the two parallel wires.

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