4-Flat to 7-Way Trailer Wiring Conversion

Does your vehicle have a 4-Flat trailer wiring harness, but you need to tow a trailer with a 7-Way harness? In this video we go over how easy and fast it is to convert a 4-Flat harness to a 7-Way harness using U-Haul part# 47185. This conversion includes the reverse lights, power wire, and brake controller wire.
To purchase this product and other towing accessories visit www.uhaul.com/trailer-hitches...
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[@kimberlyk.8569]

Great video! Thank you!

[@UncleFjester]

Incredibly useful!

[@adventuresofaidenandaviana4683]

Awesome video, have a question. I bought this part at U-Haul after watching, asked the install guy, he said on my 2013 Volvo xc60, all I need is the ground and plug in the 4prong. On a video, it said on Volvo you cannot access the brake control. It shows not connecting blue or purple wire but hook up the power wire. What do I do?

[@SAMSON-X2]

I Just Went To U Haul today. And They Didnt Wanna Mess With A Brake Controller Or A 7 way Plug . They Told Me To Take It Elsewhere. I Have A 08 E350 Van. Wow. I Never Thought They Would Do That ! In Selinsgrove Pa...

[@davenstorm7271]

Did you finally find someone to install it ? I have a Toyota Tacoma and can't believe it doesn't have the 7 pin connector on it just a 4 so gotta have it installed.

[@mediocreman2]

@@davenstorm7271 No surprise there. Tacomas are not great at towing, I'm sure the manufacturer knew that and put a 4 pin plug to help reduce people trying to tow larger trailers.

[@agustincampos8084]

Best video

[@benjaminwilkins5650]

Ok, this will work in theory but a lot of this workmanship won't last, self tappers and crimp connectors will corrode over time, if you are going to use crimps make sure to apply dielectric grease to help prevent corrosion

[@Thumper68]

No you use glue filled shrinks if you want them to last forever

[@CD-zx4zu]

Depends where you live, in the south west you can put those on and expect them to last just about forever. Glad you know about your area, but your general experience doesn't speak to everyone else's.

[@user-yj6jg7it4n]

I can't mount the bracket underneath the bumper cus it's plastic, how would you recommend getting a square shaped bracket mounted to a circular tow hitch bar?

[@andrehansen585]

Hey. Anyone know .. i have a suburban with 7 way spade., i need adapter for euro 13 pin or 7 pin. ??

[@pkeegs]

what if you have a wireless brake controller like the echo?

[@Wishfuldream]

What size fuse for the circuit breaker?

[@jeffsellers3497]

Does the charge line hook up to only the positive post? My vehicle has a U-Haul hitch and wiring (bought the used vehicle with it already installed). I have a flat 4 connector, but I also have a separate two-line wire (red & black) that comes off the positive and negative post of my car battery (with fuses). I'm guessing U-Haul put that on to charge the RV battery when towing? Do I use red, black, both? It used to have a 2-pin plug on the end until that part corroded off.

[@alejandrovaldez2620]

Hi, great video. If I do not have brake on the trailer, do I still need to connect the black connector?

[@hav1byte]

if you dont have brakes on your trailer, you dont need the blue or purple wires, maybe not the black ffor 12v aux either...better to just have a 4 flat vs. a 7 pin

[@tomlawson7847]

Great video! What is the make and model of the shrink wrap tool you are using? Thanks! Have a great day. Tom.

[@michaelbrooks4800]

It's actually a butane soldering iron with an attachment. Similar to a Berkling BSG-568 Butane Soldering Iron Kit.

[@josephbranchflower6270]

What about for a vehicle without a brake controller?

[@Bluenoser613]

For the black wire (accessory) which is also used by the Echo, doesn't it need a switch to prevent it from draining the battery when the engine is off?

[@TheChicowus]

For the Echo, you don't need the connect the blue, right?

[@DeadeyeDick1]

No it does not.

[@emmetthoffman593]

Either way, most rv owners (or other things that use the aux power) unplug it when the trailer is not in use

[@TheChicowus]

When connecting the purple wires, is the wire in the vehicle loose or did you have to cut something before connecting to the 7pin wire?

[@loglution]

It isn't loose. It's still connected to the light in the harness, the blue crimp he used splices into that so that it continues to work as it was, but also now supplies power to the purple wire.

[@bvictory5698]

The trailer I want to haul doesn’t have anything on it but lights, it is a 7 blade plug. I don’t want to run the purple or the white and blue wires. Will this still work? My trailer doesn’t have its own brakes it’s just a 12ft aluminum trailer w/ a tailgate ramp. Single axle. I’m just hoping I can wrap the bigger wires in electric tape and zip tie them up for later if I ever decide to get something bigger that has any of these needs.

[@aaronlimon4803]

If you need it for just the lights, check out our conversion here: kzbin.info/www/bejne/fnrXcpqkocqWrLs

[@joesmith7156]

What do I need to do before backing up my trailer into the water? What is the name of heat shrink tool you used?

[@hav1byte]

go to amazon, plenty of heat shrink tubes you can choose from, if you have blubs, may want to unplug before launching, if LED, no worries

[@cmac747]

What make/model is that flameless heat tool you are using on the heat shrink wire connectors? Thank you!

[@leesire]

Nice isn’t it.

[@bassfan41]

Must not be that nice. Can't find it googling it and that guy isn't bragging about it

[@garrettburt511]

Great video, I'm a rookie at this stuff - where does the black wire plug in on the battery in the engine compartment? Anything else I would need to be aware of if i attempted this myself? Just need to add the black battery charging line.

[@trailerhitches]

To attach it to the battery, just use a ring terminal and attach it to the positive post.

[@garrettburt511]

@@trailerhitches thanks!

[@garrettburt511]

Also - what gauge wires should I use?

[@Ryan63d]

@@garrettburt511 and what size circuit breaker

[@suryavaraman.4277]

I have a 4 pin connector with s trailer brake controller. Yet I don’t know if controller works. I plugged it in to a trailer with trailer brakes and didn’t work. I guess i have to bolt the white wire into ground? And wire blue wire into controller?

[@mediocreman2]

Did you even watch the video? Yes you need ground, yes you need power for the brakes (black wire), and yes you will need the signal to send to the brakes from your brake controller (blue wire), unless you have a wireless controller. I highly recommend you take your vehicle to a trusted mechanic or Uhaul.

[@CuddiWraps]

That’s good information. Now what if you don’t have that brake controller & you have a one of those Bluetooth echo controller how do you do that?

[@trailerhitches]

For the Echo Bluetooth, you need to connect the black wire to the battery using a 30 amp fuse and its ready to go!

[@CuddiWraps]

@@trailerhitches Yeaa one goes to the reverse another to the battery & what about the one that goes to the brake controller ?

[@trailerhitches]

@@CuddiWraps The blue wire isn't used for the Echo Bluetooth. You won't hook it up to anything.

[@CuddiWraps]

@@trailerhitches ohh okay so you only use it if you have the wired brake controller than?

[@trailerhitches]

@@CuddiWraps Correct

[@kennethsaras4598]

I dont have a brake controller. So where would i wire the blue and black wire too?

[@trailerhitches]

You can just tape it up to the other wires so they stay out of the way!

[@tylersheehy3918]

he said but connector

[@lanksterprice]

They forget to tell you as soon as you hit the water it sorts out and pops the fuse... TIP: Unhook your power to your trailer before going into the water.

[@hav1byte]

if you have LED, should not have any issues, just with bulbs

[@hav1byte]

you should unhook if you have bulbs, can enter the water with LED. Keep in mind, i you unplug, your boat breaks will lock up if you go in reverse

[@clarkjones2579]

No electronics in water good plan

[@harlandcofferen3346]

A scotch lock is the worst thing to use they corrode very quickly

[@jamesmeadrs9309]

Does this connection give you the aux?

[@hav1byte]

the black wire is the 12v au.

[@jessepayne6757]

Do they make these without the trailer brakes?

[@trailerhitches]

One of the 6 functions on a 7 way socket is for electric trailer brakes. Trailers that have a 7 way plug require more functions and more often than not have electric trailer brakes. A electric trailer brake controller needs to be installed in order to activate the trailers brakes. The blue wire Aaron mentions needs to be connected to the Electric brake controller installed under the dash to complete a full install of this part. However, installation of the Black wire to your Battery with a circuit breaker(recommended) or fuse holder as shown turns on 12v power to your 7 way socket. You can then use the bluetooth brake controller linked below to activate your trailers brakes without one underneath the dashboard. www.uhaul.com/MovingSupplies/Wiring-Lights/Brake-Controllers/Curt-Echo-Mobile-Brake-Controller/?id=20543. You can always schedule an installation with your Nearest Local U-Haul hitch center!

[@badboytilltheend13]

Hello. Question. I have the bluetooth brake controller. How and where do I connect the brake controller wire now? Thank you in advance.

[@trailerhitches]

For a Echo bluetooth controller, You do not need to install the Blue brake controller wire from the 7-way socket to any component. The controller takes care of the signal from itself to the trailer. However the black wire does need to be installed. It needs 12volts from the battery via a circuit breaker in order to power up the Echo Controller. Visit your nearest Local U-haul hitch center to schedule an installation. www.uhaul.com/Trailer-Hitches/

[@badboytilltheend13]

@@trailerhitches thank you for the reply. Do you guys have a video that has 7 pin connection without 4 pin connection? I have 7 pin connection that I'll be connecting to 2021 Pilot.

[@trailerhitches]

Here is a Link to the proper 7-way quick connect for a 2021 Honda pilot. Your Vehicle is prewired for all of these components. This video is specifically for adding a 7 way to a 4 way. None of which your vehicle needs. Unfortunately there is not a video of the install, but It will be easier than all this hardwiring. Here is a link for purchase. kzbin.info/www/bejne/nqGppZKsfZ6BZ7s

[@EmuSkateboarding]

Do you need to ground to car or can I ground to trailer?

[@trailerhitches]

Always ground to the car.

[@CostaRicaInNature]

Great video. Uhaul added a 7 pin to my 2018 Outback. After the installation, the running lights on the trailer come on immediately after plugging in the trailer, but the car is not running. Any idea what is wrong? I took it back but Uhaul didn't know what was causing it. Not the trailer. I had it tested.

[@aaronlimon4803]

Lets see if we can help. Your vehicle's tow harness is equipped with a powered converter box leading to a 4-flat trailer end, which is then converted to your 7-way connector. We suspect two high probability causes for your issue: 1) defective or mis-wired tow harness converter. 2) Miss-wire at the 7-way (vehicle or trailer). To diagnose, start by testing the 7-way on your vehicle. With the vehicle turned off, use a basic bulb test light to probe all 7 pins. Please note, with the vehicle off, the only pin that should potentially light up your test light, is the trailer battery charge pin located directly to the right of the alignment notch. Next is to test with the running lights on, the pin located directly to the left of the alignment notch should now also light up your test light. If your test proves proper power to the correct pins, the trailer 7-way connector is now suspected of being mis-wired. If your test proves a defective converter or mis-wire at the vehicle 7-way, please take your test results to your installer.

[@CostaRicaInNature]

@@aaronlimon4803 Thank you so much for the reply. I will do the test you suggested.

[@Butteredstuff]

They likely took a shortcut and didn't tie your powered converter box to the battery, but instead used a 12v located in the rear of the vehicle. U Haul is notorious for cutting corners.

[@CostaRicaInNature]

@@Butteredstuff Thank you

[@valbean]

What do you tow with your Outback? I’m looking to get a 16’ Scamp or casita.

[@billymcfuggin7549]

What gauge wire is the black and blue wire?

[@hav1byte]

about 14 guage

[@steventyler7663]

12 gauge should be the minimum size wire used, but 10 gauge works better to prevent voltage drop...especially if you have a long trailer.

[@user-cz2bt6ch5g]

How much is uhaul charge to install that ?

[@trailerhitches]

Labor rates can vary per area so its best to call your local U-Haul hitch center for a quote or visit us here uhaulhitches.com

[@ronaldtreitner1460]

ok i'm not hooking up a boat trailer and do not have purple wires

[@hav1byte]

you only need the purple wire for surge brakes, the blue for electric brakes...

[@richmendez726]

Is the purple wire only or primarily for boats? Do I need to hook it up for my RV? Thank you.

[@aaronlimon4803]

The purple wire is for the reverse light function. It is most common on boat trailers. If you have a reverse light on your trailer, you'll want to hook it up.

[@eltonwilliams2]

what if i dont hook up the purple wire, will the break controller still work?

[@hav1byte]

@@eltonwilliams2 the purple wire if a reverse function wire, for surge brakes, the brake controller is a totally separate issue, that's the blue wire, for electric brakes. no impact

[@hav1byte]

the purple wire is a reverse function wire, for surge brakes on newer boats, not sure of rv's....what type of brakes do you have on your rv? if surge, then purple to reverse lights wire on vehicle, if electric, then blue via brake controller.

[@julieschwank6046]

is this fuse holder an inline 30 amp

[@trailerhitches]

Yes, for the power you can use a 30 amp

[@cristianestrada947]

Useful response and useful question!

[@Butteredstuff]

This video assumes the viewer already knows what they're doing. For example, how does one source the lead for the reverse lights?

[@aaronlimon4803]

Sorry, we could have explained that a little better. So we mention that we are connecting to the reverse light wire that comes out of the tail light. On some vehicles when you remove the tail light, you can trace the wire from the bulb. If you cant, use a circuit tester to test each wire to find the reverse light function. Here's a video on how to test wires: kzbin.info/www/bejne/gnjHqWaqeL6EZpo

[@Butteredstuff]

@@aaronlimon4803 Great! Thanks! What if you're dealing with a wiring loom and gromit as you did in the video? Same story? Test light? What if it's an Audi Q5 for example, and the running lights switch from bumper to D pillar depending on the position of the lift gate? 🤔

[@aaronlimon4803]

@@Butteredstuff If you're hooking up trailer lights check out our universal wiring video to follow for the Audi Q5 kzbin.info/www/bejne/fZClZIprfZWBm7M. If the running lights change position, connect to the wire that will be running when the liftgate is in the position it will be in when towing.

[@missUMommanBro]

What if u have the wires there how do we check which is which. 4 wires light up each time no matter what I have on. I turn blinkers on and the light tester only shines doesn't blink. Please help

[@Butteredstuff]

@@missUMommanBro check to ensure the controller box is grounded adequately.

[@wallyburkhart3049]

Why not just install a 7×4 socket on your vehicle. Do not use scotch blocks, they will corrode and cause problems later.

[@planitmc1204]

Im face palming so hard when he put the scotch lock instead of the butt connection iv spent so much time cutting those things out

[@Dreskezi]

It worked for a few days and after that my fuse continued to blowing.

[@trailerhitches]

This part does not have a fuse.

[@Dreskezi]

@@trailerhitches I went to U-Haul to get a trailer hitch and wired combination installed on my Jeep. I told them that I needed the 7 pin connector. They recommended that I get the adapter. I used the adapter after 2-4 days later my main fuse for the wiring source started blowing every time I would plug it up.

[@sjoyce4824]

Called my Uhaul and they said Uhaul doesn't help with this stuff 🙃

[@aaronlimon4803]

Which location was this? I'm gonna give them a call.

[@sjoyce4824]

It was the Uhaul on Andresen Rd in Vancouver, WA. She said she'd talk to the guy who installs (this Uhaul is connected to the hitch supercenter), but said no.

[@irmageller]

THANK YOU FOR SHARING; but TO DIFFICULT. Shalom 🤔🥴🤓😅

[@mckalewirnsberger1910]

Completely no help . I’m looking how to wire the Hopkins cause the wire colors are not labeled as should be .....

[@trailerhitches]

Maybe this video can help: kzbin.info/www/bejne/r3ayo4Ruo89mf5I In this video we look at all the functions and you can use that to trace which wire has which function.

[@01abihsot]

Very poor installation most vehicles come with a plug and play system

[@trailerhitches]

The majority of vehicles on the road do NOT have a plug and play system. This is also a generic install video. Check out our other videos to see installs on your specific vehicle!