Is the built-in brake assist all I need for the electric brakes on the trailer?

Hi, we bought a 2021 4Runner and want to tow a 16' trailer, bout 4500 lbs. Reading up says it has a built in brake assist and good for 5000lb tow. Is the built in brake assist all I need for the electric brakes on the trailer, or do I need to install a separate braking system in the truck for highway towing ?

 

You will need a controller but there’s plug and play units from https://www.redarcelectronics.com/us/

The brake assist is to assist you in general braking, it isn’t a trailer brake controller.

 

I concur with Whippersnapper above. Having a separate controller for your trailer brakes is always a good idea, especially if you are going to pull at highway speeds for any real distance.

 

Does this Toyota come with the wire plug under the dash to plug the brake controller to just plug in with a harness ?

 

Is 4500# just the trailer? God damn.

 

???

 

I got the redarc brake controller. Here is a link to the install video.

https://www.etrailer.com/Trailer-Brake-Controller/Redarc/RED44FR.html

 

???

You said trailer bout 4500#. Is that the weight of just the trailer? Must be one tank.

 

Here is Redarc’s video for installing in a 4Runner.



The brake controller comes with a generic harness with pigtails, but they offer a Toyota specific harness that connects the brake controller to the vehicle harness with a plug. There’s also a switch bezel that can replace a switch blank on the dash.

 

I went with Redarc as well. Installed the control knob into the empty spot to the right of the steering wheel. Used the Redarc bezel they sell separately.

 

I have been towing travel trailers, 5th wheels, toy boxes and have had a truck camper as well for +30 years now. Not trying to be a Debbie Downer but in my opinion when manufacturers advertise tow ratings for their vehicles the testing was done with a lone naked anorexic driver on a diet on flat ground with no turns or hills and no one unexpectedly pulling out in front of them with absolutely nothing else on board but maybe the owners manual. In other words their ratings are in optimal conditions.
A long time ago I towed at the limit on the ratings and will never do it again. I stay under 75% of the max rating(loaded) as I prefer having more truck than trailer for a MUCH more safe & relaxing experience.
It is more than having enough power….brakes and suspension are just as important if not more so.
I am currently towing at 60-65% with my diesel and it is super nice having more brakes and suspension than what I might need in an emergency.
I just hope you are not over-doing it like I did.

Edit: something to consider if you are ever involved in an injury accident while towing and the investigation comes up that you are even just a little overweight on the trailer or payload, you could be legally and financially burned at the stake.
And remember water weighs 8lbs/gallon and the trailer tongue weight counts against your payload numbers.

 

Very useful info. Thanks. So in your opinion, what are reasonable limits when towing with a 4Runner?

 

3,750#
75% of the rating with the trailer loaded….my personal rule, your results may vary.
A 4,500# trailer will have around 400# tongue weight…..I don’t know off hand what a 5th gen payload is but it is not a lot. With a load of passengers/gear along with tongue weight I think it would be easy to overload.
Edit: 4Runners are not the best tow vehicles.

 

You've already gotten solid advice here, but I like to chime in sometimes:

• I have used Redarc and towed our pop-up for the last 25K miles with it flawlessly
• Redarc fits nicely under dash with a single knob installed in one of the blank out plates
• Truck does have appropriate pigtail in place for installing a brake controller
• If you're going 7-pin, you'll likely need to run a dedicated +12V line of appropriate gauge to receptacle in rear
• I've been towing our 2200# rig frequently and the lack of 4R power and need to drive in S4 are REALLY annoying
• Can't imaging towing even more weight
• Buy a scale and setup your tongue weight to ~20% of rig weight or you'll have a bad time
• Spend time getting the correct drop on the ball hitch so the rig is level or you'll have a bad time
• If you live where there are mountains (I travel in Sierras and Cascades regularly) get used to going 45mph over passes with a lot of engine noise

Jason

 

Thanks for chiming in. I’m new to towing. Can you expound on that please?

 

Good information above, you can get more info at a dedicated trailer sales outlet. 4runners don't have differential or transmission temperature monitoring so you may want to install sensors and gauges or at least have an infared temperature gun to check temperatures, don't want to overheat your transmission or diff. Always a good idea to put in thicker differential oil for towing, 75W140 or 80W140 is what most put in, I run thicker diff oil all year to eliminate a deceleration whine, change both diffs to thicker oil if your truck is awd limited. Good idea to change transmission oil at the same time.

You'll need tow mirror extensions and should check that your tires can handle extra weight or change tires to stiffer sidewall tires to reduce body roll, 20" wheels with stiff sidewall tires also help to reduce body roll, you may also want to beef up your rear suspension to airbag springs. Don't forget to have at least 1 trailer spare tire and that the tires are fairly new, I see 10 year old tires on friends rigs and wonder how those guys are still alive.

 

Yep,
If I was going to have trailer behind a 4Runner I would have either a pop top or maybe a compact 7 ft wide travel trailer.

 

It's been a few years so please confirm this advice and do your own investigation.

The stock 7-pin socket either A) doesn't have +12V on one of the pins needed to charge the trailer house battery -OR- B) it does, but the wire gauge was insufficient. I don't remember which.

So I ran a fused 10g wire back to the 7-pin socket directly from the battery. Problem solved.

I did a quick look and found this: Jason

 

-------------------------------------------------------------------------------

was looking at trailers to rent or purchase for a trip to AZ from VA this summer. a handful of renters demand that there be an electronic brake assist installed. but that is for something over 3500lbs. i was looking to be under 3k dry to allow for better handling and braking. the few times i have towed, i felt nervous the entire time even with anti sway dodads and extra wide mirrors. i know 4runners can tow 5k lb, but i think it will be hella better if i can keep it under 3k.

 

I tow frequently (pop-up camper, mountain bikes, full family, etc) and our setup weighs between 2000lbs and 3000lbs depending on where we're headed.

There's no way I'd take that rig without an electric brake controller. Not just for sheer braking force (the 4R probably has enough raw stopping power) but for stability in quick reaction situations and navigating mountains passes and twisty roads.

They're too beneficial and too inexpensive not to unless you're just taking a small U-Haul across town once a year.

Jason

 

This is the best advice regarding towing on this forum. These are words to live by.