Adding 7 pin trailer wiring

I am going to install the wiring for a 7 pin hitch on my non tow package 5 lugger. This is going to be a completely custom install. From what I understand even if you have the factory tow package it does not have all 7 wires for the 7 pin hookup. This is why I decided to do it custom. If others are interested in doing this on their truck I will make this a how to once I have mine done.

I ran a 7 wire trailer cable from my rear bumper to the engine compartment. Now I have to figure out where to tap in the 7 wires. The one for the brakes is the easiest, it will go to the brake controller. Ground can just goto a ground in the engine compartment.

For the auxiliary wire I can put a relay connected to the ignition and tap into either the batter directly or look for something in the engine electrical panel. There is a empty spot in there labeled 30 amp towing. It has a space for a relay and it already has a 30 amp fuse so I may be able to tap into that. There is also a 30 amp fuse labeled "towing tail". I don't know what that is for.

Left, right, running, and reverse are the wires that I have yet to figure out how to tap in to. I could just find those 4 wires and tap into them but I'd like to make my trailer wiring completely independent from the existing factory wiring. If anyone has done this before I'd love some info. If not I'll figure it out myself and post how I did it.

 

If I could change you mind.
https://www.etrailer.com/Custom-Fit...Tacoma/2009/118496.html?VehicleID=20091176461

https://www.etrailer.com/Wiring/Tow-Ready/30717.html

Not saying your method won't work. But this might be slighty easier on you. Less crimps overall

 

I've used a similar style harness on my old ranger. Worked better than the crap uhaul harness that was installed on it prior.

 

So, @Puppypunter has a handful of 2nd gen taillight connectors as well as a plethora of sealed relays. Pretty sure he could cook you up a custom one-off harness with 7 pin output which would only need as inputs +12v, brake controller and ground. I have one pair of those connectors for 2nd gen but no sealed relays at the moment and less experience tinkering with 2nd gens. I think the flashy flashy turn signals are the only part which gets interesting though, he's got plenty of experience with that and I'm still ramping up on those sorts of things.

I'm not sure why you're against touching factory wiring? Do you just mean you don't want to cut it? I don't see how you can be completely independent from it if you need to tap signals for reverse and turn?

 

I don't have a ton of experience with 2nd gens, but I think we could accomplish what you are looking to do with those 4 wires easy enough. We could make 2 tee harnesses from the taillights to take care of turns, running, reverse, and brake if you wanted to. As to keeping it "completely independent", well, that's a little hard to define. We could easily just use the signals to feed relays so there isn't much added draw (just 80mA for the relay coils), and if you are super-duper wanting to be careful, we could feed it through a diode and fuse, as well as a diode protected relay coil. You would have to get 12V+ to it, but that's part of what you're doing anyway. I think it's a little overkill, but I don't judge Could put all of this in a couple GEP fuse/relay holders mounted toward the rear, and I think you'd be good to go.

 

Thanks for the replies. To answer Dave's question, I just don't like the the t connector type trailer wiring because it seems like a jerry rig job even though that is what I use now. It puts more of a load on the factory wire. Also one time when towing a borrowed trailer, the fuse for the tail lights blew and that locked my truck in park. It seemed logical to me that if I'm going to have to run 2 wires anyway for the auxiliary and brakes I figured why not just have all 7 wires being feed from the front of the truck. There are many of ways to do it I just like it to be as robust as possible.