Missing Blue and Black

2012 Tundra 4.6l no towing package, originally with 4-pin connector

I'm installing a Tekonsha P3 and used the 3040-p harness to connect the controller to factory harness located behind the left kick panel. HOWEVER, the blue and black wires for power and trailer brakes do NOT make their way to the back of the truck where the original 4 way harness is located. Does anyone know where the blue and black wires go to off of the factory harness?

 

Mike,
I have a 2010 Tundra and I am adding a brake controller. The cab of the truck had the factory harness for the brake controller. I have the four flat on the rear bumper currently and I have partially installed a seven blade round. I too have not been able to locate the black and blue wires in the back of the truck. Were you able to locate these wires? if so care to share where you found them and how you made the connection?
Thanks advance for any assistance you may be able to offer.
Bill

 

That was his only post 2 years ago. He’s not coming back. Hopefully someone else answers though.

 

Thanks, It is the last piece of my conversion and addition of the 7 round and brake controller.
Anyone have any ideas?

 

If your truck only has a 4 pin connector, you may have to run at least one additional wire to the rear bumper for your new seven pin connector. The blue wire is the controller brake output to the trailer. The black is +12V to the trailer brake controller, and white is ground. Red is the controller output for stop lights which should already be available, along with tail lights and turn signals.

Have you gotten under to see what wires are in the harness to the 4 pin connector? Tekonsha says all Tundras from 2003 to 2014 use the 3040-P harness which plugs into an factory harness connector. I can't imagine they would provide a connector for a plug-n-play trailer brake controller without giving you the necessary wires back to the bumper.

 

Thank you very much for your reply JohnLakeman,
I installed the REDARC Tow Pro Elite in the CAB and used the TEKONSHA harness 3040-S to connect to the factory existing wiring harness. I installed the

$25 Hopkins 47185 Multi-Tow 4 Flat to 7 Blade and 4 Flat Adapter

Hopkins 47185 7 blade connector on the bumper of the truck. I have the 4 flat connected and working (pretty simple 4 flat male to 4 flat female), I have the white ground completed. That leaves the Black (Power), Blue (Brake Controller) and Purple (AUX and Reverse Lights) which gets wired to the reverse light in tail light. The Four flat goes under the bed. I believe the Blue, Black and possibly Purple would go under the bed next to the four flat connection. See photos attached.
Thanks for your assistance.

 

I've wired a 7-pin connector from scratch before, but it's been decades. The entire harness came from the dash, and included a black box for separating Japanese-style truck lighting to American-style trailer lighting. I also built a 7 pin to flat four adapter for when I needed to use a trailer without electric brakes.

Unfortunately, if it's more than plug-n-play anymore, I would have to figure this out again just as you will. It will be further complicated by my not knowing how your truck came equipped, and how much you've already improvised. I recommend contacting REDARC's tech service guys for assistance. Sorry, I can't help you on this one.

 

Thanks for trying. I spoke to REDARCH Tech at Midnight Central time in US, they were happy to help but said wiring is different in US.
I spoke to eTrailer as well and they said everything should be there near the spare tire. I think I will need to run a hot wire (Black) from battery to back of truck and run brake controller wire (Blue) from Cab to back of truck and be done with it.
Happy Thanksgiving!

 

Here's a wiring diagram from the internet (US style). Good luck.

 

OK, from a little research, I know/remember more than yesterday. (Dohp! )

Yes, if your Tundra has only a flat four, then for the 7 pin round, you will need to run +12V directly from the battery for the trailer brake emergency disconnect (when trailer separates from tow vehicle). This wire should be un-switched, or hot all the time. I remember now that mine was simply connected to the battery positive cable end bolt using a large eye terminal. An inline fuse is a good idea.

You will obviously need to run the blue wire from the brake controller back to the round 7 pin connector as well, since your Tundra never had a 7 pin connector. Back-up lights, you're on your own...If I needed them, I would probably improvise a back-up light connection from one of the tail-lights.

Since your Tundra never had a 7 pin connector, you will want to check your Tundra's Trailer Weight Rating (TWR) in your owner manual. Present day Toyota recommendation is 1000 pounds maximum for an un-braked trailer.

 

Thank again John. I think I have it now. I pulled wire through the free to the engine compartment and have everything connected on the trailer end. I connected the purple back up light wire to the truck back up light on the drivers side tail light. I will uti life a 30AMP circuit breaker on the black power wire going to the 7 blade adapter. I connected a test light and I have power at the center blade, brakes, running lights, and directionals.So I am almost finished.
Will let you know how it turns out.

 

John, project completed! Seven blade installed as well as the REDARC brake controller. My Tundra had a four pin installed and did have the additional harness for the additional brake controller. But it was not quite the simple. The red wire in the existing truck harness activates when the brake pedal is pressed. the white is a ground (I added an additional) the blue is the brake controller wire. I did not use the harness for the brake controller and hard wired it. The blade is the power, I did not use this wire as well, hardwired this as well.
I ran a power wire from the engine compartment to the cab with a 30AMP circuit breaker installed. The blue brake controller wire was pulled to the engine compartment and then connected to the wire I pulled to the bumper of the truck. Also ran a power wire to the bumper with a separate 30AMP circuit breaker. Had to add a 30 AMP fuse to the under hood fuse box for the harness inside the truck to have power.
I hope this helps someone else who is trying to install a brake controller and convert from a four pin to a seven blade adapter.
Have a great weekend everyone.

 

I'm pretty late to the discussion but I just got here this morning. My 2011 Tundra (5.7) lost the trailer aux power a while back. I got the truck used with less than 5k miles on it (110k miles now) but I'm pretty sure the towing package was factory. It has the 4 pin & 7 pin plugs with a brake controller. I've hunted everywhere I can find to see if I blew a fuse but I can't find one to replace. Anyone have any ideas where it might be? Thanks!

 

Your question will have more views if you repost as a new thread.

Click on "Forums" at the top of the page, then choose one of the discussion forums such as New Member Introductions, General Tundra Discussion, 2nd Gen Tundras (2007-2013), or Towing and Hauling. That will give you more views from members that specialize in 2nd Gen or towing. Post-a-new-thread button is on the upper right of every forum page.

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