Trailer Brake Controller Prewiring

[Kokorone]

It looks like the 4Runner SR5 has a prewired connection just behind the blank trailer brake controller panel! Huge win for future upgrades here.

 

[Kokorone]

Still digging here. These might not be the wires we are looking for

I was under the impression the controller plug would be on the left of the steering wheel but it may be on the right.

Will update later!

 

[Gastan]

Still digging here. These might not be the wires we are looking for

I was under the impression the controller plug would be on the left of the steering wheel but it may be on the right.

Thanks for taking apart your dash panel to see what prewiring you have!

As I posted in this thread - Aftermarket Trailer Brake Controller -- DIY how-to install instructions unfortunately the 2024 Tacomas that aren't fitted with Tow Tech Package from the factory don't have a pre-wired wiring harness to connect the OEM Toyota trailer brake controller.

I was hoping the 2025 4Runner would be different and would have a trailer brake controller wiring harness pre-wired behind the panel even if it doesn't have the tow package. Fingers crossed you find one.

 

[Kokorone]

Thanks for taking apart your dash panel to see what prewiring you have!

As I posted in this thread - Aftermarket Trailer Brake Controller -- DIY how-to install instructions unfortunately the 2024 Tacomas that aren't fitted with Tow Tech Package from the factory don't have a pre-wired wiring harness to connect the OEM Toyota trailer brake controller.

I was hoping the 2025 4Runner would be different and would have a trailer brake controller wiring harness pre-wired behind the panel even if it doesn't have the tow package. Fingers crossed you find one.

I was unable to find anything similar to what the tundras have in terms of color of wires and position but this connector type is exactly the same as what should be compatible with a trailer brake controller. I’d be interested to see if this is in fact the right connector if anyone has a redarc to connect to it using the tph-021 harness.

Here is what the tundra plug looks like.

 

[Kokorone]

Just a little comparison with zoomed in pics.

First the Tundra

Then the 4Runner

Something of note based on the forum here:
https://www.tundras.com/threads/adding-trailer-brake-controller-to-sr.108436/page-2

The white connector shown actually is exclusively for the models without the brake controller from the factory. If the car comes with it, it’s completely absent and reterminated into a black plastic connector.

 

[4running]

The white connector shown actually is exclusively for the models without the brake controller from the factory. If the car comes with it, it’s completely absent and reterminated into a black plastic connector.

So the conclusion is that your SR5 without factory tow package DOES NOT have the prewired wiring harness to install a trailer brake controller?

... based on the fact that it has that white connector, instead of black connector - did I understand that right?

 

[Kokorone]

So the conclusion is that your SR5 without factory tow package DOES NOT have the prewired wiring harness to install a trailer brake controller?

... based on the fact that it has that white connector, instead of black connector - did I understand that right?

Unsure. This white harness is the prewired that tundra users can install trailer brake controllers with. If it is what it looks like you can very easily install something like a Redarc in just a few minutes. It just doesn’t work with the OEM brake controller.

 

[Kokorone]

I don’t have a redarc with the right harness to plug into here and try it

 

[jdgreen]

If the white connector is for attachment of an aftermarket controller, it seems that Tekonsha or others would soon build a custom jumper to go between their controller and the connector. But if the white connector is for the OEM brake controller, then why couldn't a OEM unit be installed? I found a Toyota part number 84391 that appears to be the OEM control unit. Perhaps there's more to it than that?

 

[jdgreen]

If the white connector is for attachment of an aftermarket controller, it seems that Tekonsha or others would soon build a custom jumper to go between their controller and the connector. But if the white connector is for the OEM brake controller, then why couldn't a OEM unit be installed? I found a Toyota part number 84391 that appears to be the OEM control unit. Perhaps there's more to it than that?

As others have mentioned, the Tekonsha Prodigy RF is verified by eTrailer to fit 2025 4R, and it's plug & play, but doesn't require an under-dash connection. It works via Bluetooth.

 

[Kokorone]

As others have mentioned, the Tekonsha Prodigy RF is verified by eTrailer to fit 2025 4R, and it's plug & play, but doesn't require an under-dash connection. It works via Bluetooth.

Definitely an option, but seeing as Bluetooth often requires your phone to have the app active and its tough to use in a pinch where a physical control would be preferred I wanted to investigate if its easily addable aftermarket from a hardwire perspective

 

[jdgreen]

Definitely an option, but seeing as Bluetooth often requires your phone to have the app active and its tough to use in a pinch where a physical control would be preferred I wanted to investigate if its easily addable aftermarket from a hardwire perspective

The Tekonsha Prodigy RF doesn't use your phone. It has its own little control panel that plugs into a 12 volt receptacle (cigarette lighter).

 

[Jetsareus]

The circuit at the connector would certainly have two large gauge wires, - power and ground. The brake pedal input and control output wires plus a panel lighting would account for all of the wires shown.

A search near the bumper may reveal one of the smaller output wire.

 

[ryno]

take a test light and or do a continuity test between the harness and 7 way at the hitch , or if its just a connector back there also? I'm curious as ill be installing. swing spare tire and need a power lead for the new plate light. I haven't taken delivery yet..

 

[Jetsareus]

I agree with Reno. BTW, the schematic is a generic for discussion, not Toyota.