Yes, I searched.

I'm towing a 6'x12' U-Haul trailer this weekend from San Diego back to Phoenix and had some questions. First off, I can't for the life of me find the little yellow wire harness thing that was in my glovebox. What's that for and do I need it? If I do need it, where can I get a new one this week?

Second, obviously never towed anything in my life before. Any last minute suggestions and tips? From my searches it looks like I'll be keeping it in 4th gear the entire drive and taking it slow and easy especially on the mountains coming from San Diego down to El Centro. Won't have to do too much manuvering which is nice and shouldn't be backing it up to anything which is also nice.

Any help is appreciated.

It'll have surge brakes, so you don't need a brake controller, just a hitch ball and draw bar. Leave extra room between yourself and traffic. Keep in mind the trailer takes turns tighter than you do, so keep an eye on it in the mirrors when turning, especially around gas pumps. Try to center most of your weight middle to slightly forward of the axle(s).

I have the hitch ball. What's the draw bar? Probably really stupid question but total towing rookie right here.

Also, will I need the wiring harness at all?

Tongue weight (the weight the tongue of the trailer places on the ball) is very important in keeping the trailer behaving properly. It is supposed to be 10-15% of the trailer + contents. Too light = squirrely trailer.

Make sure all your trailer lights work. Check them every time you stop. Allow double your normal following distances, anticipate stops, your braking distances will increase a lot. You really don't want any emergency maneuvers. Set your mirrors to see the lanes NEXT to you. Have the trailer shop show you how to hook up the safety chains.

Be careful, take your time, you'll be fine.

Draw bar is what the hitch ball mounts to, think 2 inch channel that comes off the vehicle, held on with a locking pin, slides into your chassis hitch.

You should be fine without any type of harness adapter. 4Runner has both 4 and 7 pin connectors. If I remember correctly U Haul uses 4 pin connector. If you need anything to adapt they should have it at the U Haul store.

Remember in CA you're limited to the 2 far right lanes while towing. CHP loves that rule.

The trailer will plug right in without that pigtail. I have towed those 6X12's several thousand miles with my 4Runner and the trailer loaded to about 4600 lbs. I towed at 65-70 mph and got around 11 mpg fully loaded. Use sport mode, take your time and you will be fine.

Can't help you on the draw bar. He may mean the receiver bar that the ball goes on. Different names in different parts of the country. You may not need the wiring harness depending on what plug the U-haul trailer has. But U-haul should also have an adapter to fit your plug for a fee if it is needed. If not your nearest Toyota dealer should be able to set you up with another adapter pigtail.

If for some reason the trailer gets squirrelly on you and starts whipping around, for pete's sake don't try to correct it. Roll off the gas and hold the wheel as straight as you can while you slow down. If you have to use the brakes do it very lightly. The trailer should settle down as you slow. Trying to correct for the gyrations generally just makes them worse. This is also the reason you want the weight to be slightly forward on the trailer. Rear biased weight will actually unload your ball and make it squirrelly. Better to have too much forward of the axle than too much behind it, but balanced slightly forward is best. Otherwise just drive normally and remember you have an extra axle and weight behind you. It's really not as difficult as we sometimes make it.

The ball is bolted on the draw bar. The draw bar slides into the receiver, held by the hitch pin.

Which wiring harness are you referring to? The trailer plugs into the wiring plug down by the hitch receiver... you have to crawl to see it. Don't let the wires drag.

Also, do you plan any overnight stops? Everyone knows to padlock the trailer doors, but you should be aware that entire trailers can been stolen by simply unlatching the trailer hitch off the ball. Or if you have padlocked that, the hitchpin can be pulled out of the drawbar. Guessing the rental place can help you there.

And thanks for your service. Safe travels.

Phil FT2, USN 1960-1964

Good to hear. I don't expect good mileage at all so I'm not worried about it. Glad to hear the 4Runner can handle it no problem.


No overnight stops. It's only about a 5 hour drive from San Diego to Phoenix and I'll be leaving either late morning or early afternoon on Thursday.

Don't forget that the speed limit while towing is 55 in Cali. Another 'great' rule they hammer you on.

As others have said, no adapter needed. Uhaul trailers will plug directly into your truck (underneath to left of hitch). If you see a clear gel-like substance on the connector it's there to protect the connector and prevent corrosion. May want to pickup some up and reapply after your trip especially if you are in the desert. Load your heavy cargo front-center of the axles. Safe travels.

Remember to bring a lot of water and sun protection in case you have a problem. It is 110 degrees in the desert this week with occasional monsoon storms. Do those rental trailers come with spare tires?

Although many posted great tips and recommendations, I didn't see where anyone addressed just what exactly the "yellow wire harness" was in your glovebox.

That is to wire up a separate brake controller to the factory harness under the dash. It simplifies the wiring for you if you plan to add an aftermarket brake controller. Something I don't think you will need with your uHaul trailer. If you were hauling a trailer regularly that has trailer brakes, then it might be a good idea - otherwise, I put mine in the jack compartment so that I wouldn't lose it!

Thank you! Glad to have that cleared up. Mine stayed in the glovebox until my truck got broken into then my wife took it out and now it's lost. Glad to know I won't need it.


I'm painfully familiar with this drive so I know that 55 is what I'll be going in California and I know CHP are a bunch of sticklers for stupid things so I want to avoid all that. I'm just hoping that the winds won't be too bad.

Even if you do get a trailer with electric brakes and add a brake controller, you're better off buying a wire harness that fits the controller on one side, and the 4runner's plug on the other. The harness you lost would need to be spliced with the harness that comes with the controller.