So, I recently bought an all aluminum car trailer and was told I’d need a brake controller, so I picked up a Tekonsha P3. While reading about it, I learned that Tekonsha makes a direct plug and play harness, so after more research I learned that I needed the 3040-P harness, which I promptly ordered from Amazon. I was pretty excited when I saw the quality of the harness until I went to actually plug it in, that is! According to the instructions I read, and video I watched on etrailer, the white factory plug is right above the driver’s side kick panel under the dash. I actually have 2 plugs there, but neither one fits the Tekonsha harness! The pre-made harness has an almost square, white connector, while the 2 white connectors under my dash are slightly more rectangular and won’t fit. Has anyone else encountered this issue? I called Tekonsha tech line and they were ZERO help! They just told me that is the correct harness for my application and my only recourse would be to hardwire it, which I would like to avoid if at all possible! I actually have pictures of the connectors, but don’t know how to post them here.

I hit the link you have posted and typed your 04/v8 in, states DOESN'T FIT YOUR VEHICLE.

Web search "3040-P harness" then input your vehicle info in it for fitment. Depending on the controller, you might have to cut the small end and splice the ends.

Edit- just hit your link again, and now show a different one.

Just order from Etrailer, you can do the same check there. I've had to order from them for the rear 7pin plug and direct plug fit.

Here is the link to to controller I have on etrailer, and this one comes as a package with the exact harness I ordered, which is vehicle specific fitment to our 4Runners. I ended up ordering it on Amazon after finding the part number here. There is even an installation video in this link showing it being installed on a 2004. This really bothers me because it “should” plug right in!

Tekonsha Brake Controller for 2004 Toyota 4Runner | etrailer.com

My truck came with a trailer adaptor in the glove box and it is a fairly square connector, not sure if it applies to this situation or not but is that what's missing possibly?

Had the same problems before dealing with Amazon. Find the PN then google it and shows on Amazon, run a fit check then no go.
Why I try avoiding Amazon/Ebay on things like this.

I had the dealer one in the glove box when I bought my ride, been in stalled for 10yrs now.

No, but from all the images online I’ve seen, the connector on the harness I have is identical to that connector you have, which means it should plug right in. The problem I have is that the 2 connectors I found near the parking brake (where the trailer plug is supposed to be), are no where near correct to fit it. I wish I knew how to post pics here because maybe someone could tell me what those other 2 white connectors are for that I found. They are taped together, but I can’t see anywhere they would plug in under there. I’m perplexed that I can’t seem to find the correct square one though! It’s supposed to be part of the factory harness for all 4Runners with the 7 pin connector near the hitch. My truck has the class 3 hitch setup, and 7 pin connector, and everything looks plugged in to factory harness back there, so it must be factory.

Yeah, I ran into that when I installed the “smoker’s kit” to replace the original ashtray. I looked up the part number that someone posted here on amazon, and it said it wouldn’t fit my vehicle! I knew it would, so I ordered anyway, and it fit perfectly. In the case of this harness, it is exactly the same part number as on the Tekonsha site, etrailer, etc., so I know it’s correct, and the tech at Tekonsha verified it was the only part number for our 4Runners, other than the same harness made by Reese, but the connectors are identical anyway. I’ve also looked at images of the dealer pigtail like you have, and the plug is identical as well, so now I just have to figure why I don’t have the male side under my dash where it’s supposed to be! I would hardwire this harness, but I have no clue where to tap it in without that plug anyway...

I'll check when I get home this wkend and see what's under there.

Thanks, I appreciate your help!

3040-P Tekonsha Plug-In Wiring Adapter for Electric Brake Controllers - Toyota and Lexus
2
$12.40
3040-P Installation InstructionsINSTRUCTIONS
CLICK HERE FOR MORE VIDEOS/PRODUCT INFO

EXPERT ANSWERS

Tekonsha Brake Controller 3040-P Review

Trailer Brake Controller Installation - 2004 Toyota 4Runner

This is the part # I put in my 05 V8 4runner and my 2015 tacoma PM me with you cell # and I can text you photos of what it looks like under the dash. or just text me 978-886-seven826

4runner is a dream to install compared to the bloodletting that my tacoma put on me!

Eric

Thanks to Eric and his helpful pictures and info today I was able to find that elusive connector and get my PS3 controller mounted and functional! I guess I was so focused on those 2 plugs that were in the general location where the brake harness was supposed to be that I missed what I was actually looking for, which was the square plug. It was more toward the front, and was vertical and buried behind the main harness so I didn’t see it last time. After seeing his pics, which showed the other 2 connectors I found, it really helped me zero in on it, so once I took a bright flashlight and moved the harness, I spotted it!

I love this forum!