Help Tekonsha P3 issue

Okay, so I’ve now bought 2 P3’s to install/try in my 2016 OR.
One off EBay and one from brand new from Amazon.
I also bought the plug and play harness from Amazon.

Each one says camper trailer not connected, even though the lights and blinkers work and it locks up the breaks keeping me from towing it.
If I unplug it I can tow the camper no problem.
I’ve sanded on the connects to make sure there is no corrosion and I’ve checked to make sure the emergency pin in the camper hasn’t been pulled.

I can’t have bought 2 defective P3’s so thinking it’s on the campers end, but the lights/electrical is working on it and the guy I bought it from towed it with a Jeep Wrangler (not sure what brake assist he ha)
Figured I’d give this a try before I pull it to a local camper dealer.

I’ve researched on here, for anyone with a similar problem, but I’m either not asking the right question or I’m the only to have this issue with this plug and play.

Thanks for any help.

 

Check that your trailer wiring matches standard. Don’t be concerned with wire colours, just function.

 

Okay forgive my stupidity on this, this is a learning situation for me.


If I’m not going off color how do I know if the brake wire is connected in the wrong spot?
I really appreciate your help already

 

Check out the towing bible
https://www.tacomaworld.com/threads/the-tacoma-towing-bible.4031/

 

There should be no brake output if the controller is not showing detected. Use a voltmeter to measure the voltage across "Brake Controller Output" and "Ground" using the helpful diagram @landphil posted. If there's no voltage, that proves the issue is the trailer. If there is voltage and the P3 isn't detecting a trailer, the harness may be hooked up wrong.

You can also get testers for cheap if you don't have a voltmeter - this is cheap and easy:

$12 CURT 58270 7-Pin RV Blade Trailer Wiring Towing Vehicle Socket Tester, Black

https://www.amazon.com/CURT-58270-Vehicle-Socket-Trailer/dp/B001EOWQY4

What harness are you using? With the brakes being just on and it not detecting the trailer I'd say you need to look at your harness and make sure it's the correct one and that it's not plugged in upside down or something.

 

Did you connect the ground wire? Are you sure it's getting a proper ground?

 

Grounded it here

 

I think that's where I grounded mine, so that should be fine. As others have said, I think you need to check and confirm your trailer's wiring. I'd trace the wires from the brake to the plug. Ensure that they're not broken and that they connect to the plug in the proper position. If you look at the plug cover on your Tacoma, it shows you the proper wiring diagram for your truck.

 

Do you have a basic test light? This is the ideal tool for sorting thus out, along with a piece of 14ga or 12ga wire for a jumper to use on the trailer.

 

I do have one

 

Ok, so here’s what I suggest, and hopefully your camper trailer still has a battery installed in it as it makes it easier. And leave your truck out of the picture for now.

Connect your test light ground clamp to a good, clean ground point at the front of the trailer. If your battery is mounted up front like many, you can use the negative battery terminal. Or a coupler bolt. Or...

Following the upper diagram I posted earlier, put your test light probe into the “12V power” pin on the upper left. Your light should glow. If it doesn’t, test all other pins for power to find where that wire actually is connected (you should only have power on one pin) and move it to the “12V power” location of your plug.

Next, pull the breakaway switch cable to power the trailer brakes from the trailer battery, and use your test light to figure out which of the pins is now powered by this. It should be the lower left, labelled “Brake controller output” on the lower left, and if it isn’t, move the wire to that pin of your plug.

One word of caution though- don’t leave the breakaway switch pulled for more than 30 seconds or so, as the brake magnets can start overheating and failing.

Now, to check that your light connections are correct - grab a short piece of wire with stripped ends for a jumper. Have someone watch your lights, and jump one at a time between the “12V power” pin on the top left to “left turn / stop”, “right turn / stop”, “tail and running lights”, and make sure the correct lights are lighting up. If not, move those wires to where the diagram shows, and re-test. ( I doubt your trailer has reverse lights, but if it does, you can repeat this for them as well)

Last step would be to test the ground connection. Hold your test light ground clamp against that “12V power” pin on the top left, and poke the probe onto the lower right pin labelled “Ground”. You should have a lit up test light.

If anything was out of place and you moved it, I’d now suggest connecting your truck and trying a test drive. If all was good...

 

@landphil thanks a ton for the help/directions!
I’m stuck at work through Thanksgiving, but as soon as I get home and get a chance to work on it I’ll definitely be doing that

I’ll post the update as soon as I can


Thanks for everyone who has pitched in!

 

If your trailer matched the diagram, then it’s time to check the truck 7 pin connector. Connect your test light to a good clean ground on the rear of the truck.

Turning the key on should power the “12V power” pin in the top right, Using the brake controller manual lever should power the “Brake controller output” on the bottom right, and tail, RH signal, and LH signal, and reverse light speak for themselves.

 

I was hoping to comeback and give a positive update a couple weeks back with a success story for anyone that helped like @landphil but I’ve been soundly defeated and had to get away from the project for a couple weeks.

But here’s where I got. I followed the diagram/instructions that you gave and everything appears to be working/wired correctly on the trailer.

I bought a 7 pin curt tester for my truck and everything works as it should on it.

But the Tekonsha P3 still doesn’t detect a trailer connected, even though all the lights work while connected and it keeps the brakes locked up preventing me from towing, so long as the Tekonsha is hooked up.

I would guess the Tekonsha is bad, but this is the second one I’ve bought with the same issue.

Currently thinking I should just buy another truck, camper or both

 

Given my experience so far with Tekonsha on my '06 TRD, I'd be inclined to blame their unit and/or the harness.

I have been considering a Tekonsha for my new '21 TRD OR AC. Their web site does not show a harness for the '21 - only the '20 and earlier. Calling them got me nowhere - the sales/customer service rep I talked to passed me off to Tech Support who never answered the phone.

eTrailer.com shows a harness that's allegedly compatible with the '21 TRD, but I'm not completely comfortable with how it's listed. I'm beginning to give up hope that Tekonsha will work and am considering going with something like a Redarc Tow-Pro Elite which is a bit more costly. The advantage would be that I can mount the main unit under the seat and then I'd only need to find a place for the control knob in the dash. Meso makes a panel just for this.

Since I only have about 40 miles on my TRD at this point, I'm going to wait until I'm more familiar with the truck. Not yet sure where the best place for the controller knob would be, and I still need to decide on whether or not I'll use a weight distribution hitch. My typical trailer weight (loaded) will run around 3-4K pounds carrying my rather pricey sub compact tractor. Want to be comfortable that I won't ever lose it.

 

I’ve got the tekonsha brake controller as well and haven’t had a single issue. 2019 trd Tacoma off road. I haul a 20’ car hauler trailer and carry my mahindra 1626 with loader/grapple and a box blade or bush hog on rear or even tiller. Have no issues.

 

By the way, if it’s saying not connected it’s very likely your trailer. Could be the ground but unlikely. There’s a wire that runs through the housing of the brake axle and sometimes that wire brakes or shorts or whatever. Another possibility is the magnet on the brakes. There’s plenty of info on google and YouTube how to diagnose and change either.

Coming from the truck though very likely if your lights are working then the system is setup properly. Check the lights, brake lights, turn signals. If all function then all that’s left is the breaks. Should be very simple fix and nothing to do with the brake controller itself.

 

Okay, but with the Tekonsha why is it locking the breaks up on the camper?
All the lights work with it.

When I troubleshoot through the TP3 it gets a battery volt reading, break out put reading when I step on the break.
The other two readings are at 0.

If I unhook the TP3 and it’s just truck and camper I have lights and can pull it no problem.

 

Usually when a trailer locks up like that it’s because you need a reverse wire connected. If the reverse is connected properly, I would check the grounds on the brake controller, and also the trailer itself.