7-Way Trailer Wiring Review and Testing

In this video, we will review a 7-way trailer wiring harness (U-Haul p/n# 47185), what makes it different from a 4-flat and how to locate and test it's functions. This is one of the most common types of trailer wiring and understanding how it works can help you troubleshoot problems down the road.

ABOUT U-HAUL Since 1945, U-Haul has been the No. 1 choice of do-it-yourself movers, with a network of more than 21,000 locations across all 50 states and 10 Canadian provinces. U-Haul Truck Share 24/7 now offers customers access to U-Haul trucks every hour of every day through the self-service options on their Internet connected mobile devices. U-Haul customers’ patronage has enabled the U-Haul fleet to grow to more than 150,000 trucks, 112,000 trailers and 40,000 towing devices. U-Haul offers more than 581,000 rooms and more than 51 million square feet of self-storage space at owned and managed facilities throughout North America. U-Haul is the largest installer of permanent trailer hitches in the automotive aftermarket industry and is the largest retailer of propane in the U.S.

[serguei]

Thank you for putting this video together.
This is how every DIY video on YouTube should be: short, informative and straight to the point! Thanks again

[daved]

One of the best videos on YouTube about trailer lighting TY!!!!

[hamradiowithkevin]

Thank you for making this video; it was really helpful

[seanclark]

Outstanding Video. Very informative and to the point.

[MrTeff]

Perfect, thank you. But next time, nix the music. It's distracting. Or at least turn it down.

[cherylnunez]

I have a 26' trailer and HAD a winch to load vehicles into it. My original winch setup had a small motorcycle battery with a solar panel recharging it. I ended up getting a 12v battery powering a larger winch. I could get a larger solar panel, but would rather have the battery charged by the engine. The plug is 7 pin. Can I charge the battery from the charge pin? Is there wiring to be done on the truck side?

[madisonhadley]

The only thing that doesn't work on my suburban is reverse lights. Thanks for the great video!!

[nicholasmassaro]

So we’re just going to pretend that he didn’t grind down the bolt threads he used as a frame ground? 😂 great video though 👍

[lukehalkett]

I’m trying to splice the wires together. How would the colours correspond with the pins? So what does each colour do?

[hussainbarat]

Thank you for the video. if I will get wireless brake controller what will I do with the wire on the 7 pin connector? Do I need to connect it anywhere?

[yvfbkiv]

Question.
i have an 02 Dodge Ram 1500. My 4 pin flat connecter on vehicle for trailer works fine. EXCEPT THE RUNNING LIGHT. My 7 pin connector on vehicle for trailer works fine. EXCEPT THE RUNNING LIGHT.
What do you recommend?
Thanks.

[waynew]

I have a 2012 Nissan Titan with a tow package. You mention the 5th wire as the brake function wire. I DO NOT have a brake controller in the truck. Do I still have functioning brakes on the trailer, or do I need a brake controller? Thank You

[jaymonroe]

We have a 7 wy coming off the motorhome and a 4 way on the tow vehicle. I want to bring a power wire from the motorhome so I can keep the battery charged on the toad. I have a trickle charger for that purpose. How should I wire the toad? Thnks

[AmericanTrapper]

My trailer brakes lock up in reverse. Started after I wired in a new 7 blade

[juanmoreno]

My brake one doesn’t turn on what does that mean other lights work tho

[dougmead]

I've been having problems with my boat trailer lights intermittently going on and off. All other turn signal, brake lights work fine, I suspect loose connection in the plug here, on the inner, truck side. Anyone have same issue? Thanks!

[mrobvious]

Great video. I have an 02 Silverado 1500 2 wheel drive. I am the 2nd owner. On the back bumper there is a 7 way trailer hook up with a backup alarm.. I've always used it with that GM adapter that you stick in so you can use your 4 way pin from your trailer. I have no intention of using trailer brakes since I only have a single axle 12' trailer. Right now I plugged in one of those little led testers into the adapter and it blinks when I have left turn and right turn and flashers. But the green led light that's all the way on the left does not light up when I apply the brake or turn on the headlights. I have 2 questions for this scenario.. Is there a way for me to return this to a 4 way pin set up so I don't need the GM adapter, and while I do have this thing on my truck, how would I go about figuring out why the tail light running light does not make the green light turn on? I assume I have no problem with the fuses because the other green lights on the little tester work. And of course I do have tail lights working on the back of the pick up truck.

[hnstevens]

After harness installed, neither of my rear turn signals work when the truck ignition is turned on. Why?

[msnive]

Can I do this with a multimeter? Which mode should I use?

[JoseGonzalez-pfvx]

You didn't specify the wire colors to install.