2020 Tundra - Brake Controller

Hi! New to the group, but been reading lots of great info on here last couple of weeks.

We bought a new travel trailer a couple months ago and have experienced weak braking on the trailer. At first I thought it was the trailer and even replaced all 4 brake assemblies, but still got weak braking power. The other day I severed the blue brake wire on the backside of the harness just behind the rear bumper of my truck. With my trailer plugged in and gain all the way up to 10 I only got about 11 amps on my multimeter. I then tested the individual brakes on the trailer and got about 2.8 amps. It's a dual axle trailer with 10" brakes on all 4 wheels, so the 2.8 times 4 adds up to about 11 amps which is what I got on the truck output. From my research each brake should get 3.2-4 amps and the truck should put out a max of 16 amps at full gain. So I took my truck to Toyota for the second time. After a few hours the tech called me and said it checks out to factory specs and 10 amps is about the max output for the electric trailer brake controller. He said Tundras prior to 2012 would put out close to 20 amps, but later models were only rated for 10 amps. Sounds like Toyota has messed this up! My trailer is only 5,000 lbs so well below the towing capability of a Tundra, but it doesn't supply enough power to properly brake a dual axle trailer.

I just ordered a Teknosha P3 brake controller to see if that will correct the issue and supply enough current to the trailer brakes. The Tekonsha website and other sites like etrailer say the P3 isn't compatible with a 2020 Tundra but I called tech support at Tekonsha and the guy said they have notes in their system from people saying it does work but it's just not published yet. He said get the

$23 3031-P Tekonsha Trailer Brake Controller Harness, Compatible with Select Toyota Tacoma, Tundra

3031-P wiring harness and that should plug right into my Tundra to connect the P3. Fingers crossed this works!

If it works I'm going to ask Toyota to reimburse me for the after market brake controller.....

 

Did you check with Toyota first? There was a TSB that some said helped, even on new models. There’s a couple of threads about it.

 

Not an uncommon problem.

Tekonsha guy is close, but the

$23 3031-P Tekonsha Trailer Brake Controller Harness, Compatible with Select Toyota Tacoma, Tundra

3031-P is not a plug-n-play harness for 2018+ Tundra, only for 2015?-2017. In fact, for maximum economy, you could probably just extend the wires of the universal harness that comes with P3 and forget the 3031-P harness.

The harness connector used to hard wire an aftermarket controller is on the passenger-side upper dash/firewall (2018+). You'll have to extend the blue (controller output) and black (12V+) wires to reach. Use Search to find a ton of threads by owners replacing the IBC with aftermarket controllers. If you can't find anything useful, shout out.

Your next question after installing the P3 will be: "How do I stop my Tundra from telling me I don't have a trailer connected, when I don't even have the IBC anymore?" Do the Search.

Oh, uh, good luck getting Toyota to refund your money for the P3.

 

Thanks for the info! The P3 should be here today so I'll try to get it installed tomorrow. Annoying that Toyota can't figure this issue out!

 

His is a 2020 and the TSB was for 2016-17, but that doesn't mean Toyota corrected it. They are still using the old gray sealant for the cam towers instead of the black sealant.

 

Yeah but I’ve seen posts where 20/21 owners got theirs fixed by this or another tsb. I don’t feel like searching though.

Did Toyota diagnose it? What did they tell you when they said they couldn’t figure it out?

 

Yes Toyota did say they diagnosed it. I had it in there twice in the last week. The guy said per factory specifications after 2012 the Tundra has only put out approximately 10 amps max from the IBC. He said there was no fix for it, but I didn't know then to ask about this TSB thing. My new P3 controller arrived yesterday though so I'm going to install that and see what happens. Sounds like it is a far superior brake controller and I'm going to be towing a lot so might be worth it anyways. I'll update here once I install it.

 

There was no IBC for 2013 or earlier.

 

Let us know how it goes. There’s also a mount for a P3 that fits where the stock controller was.

https://www.esptruck.com/product-page/p3-brake-controller-mounting-kit