"Factory" 7pin Trailer Harness Installation

These are the none towing wires in that plug

 

This was very helpful! Thx, so wire is in fact carrying the 12V+ charge to the 7pin socket for RV battery charging. Also makes sense for the relay so you don't kill the truck battery leaving the RV plugged in but where is that battery charge relay? Didn't see the location in the engine compartment fuse block

 

Thanks again but shoots, my truck doesn't have that nor the wire terminals beneath so no chance of just popping it in.
Also just noticed Mine doesn't have the smaller fuse box that's next to the big one on the firewall side

 

If you get a wrecked truck, remove the top plate of the engine fuse box and remove all wires needed.

 

Has been established on here that due to voltage drop trailer batteries will not be charged properly via the 7-pin

 

Yeah upon seeing that wire I think I might up it a size, that should help

 

I have a 10ga wire running to my aux battery in the bed. I haven't checked voltage drop on that run yet.

 

Probably zero. Did you hook it up via relay that's triggered by your key?

 

It's connected with a blueseas si-acr

 

What does wire #18 do? And #10 & #11?
The reason I think that the factory towing converter relay isn't the same as the one that comes in the Toyota 4pin harness which @Sandman614 installed is the very fact it's got only 4 wires and is missing the trailer reverse light wire which on the factory tow package for sure comes somewhere from the front of the truck... I still don't like the idea of splicing into the tail light. Those wires are thin as it is...

 

Edit: in addition to the trailer lights thefqctoey towing package also has the trailer backup lamp on its own circuit with its own relay & fuse separate from the OEM backup light circuit:

https://www.tacomaworld.com/threads/help-towing-plug-wiring-reverse-lights.150906/

The relay (a standard one like the fog light relay) is behind the glovebox to the left of the ECM and has 4 wires connected to its socket. I don't even have the socket, only the white clip that would hold it:



I'm not sure if it's my OCD kicking in but that's probably like that for a reason and just splicing into the existing backup lamp harness (or even using that circuit) seems a bit like hack to me... not that I plan to back up a huge RV for miles but fuses do blow rather quick

 

You already posted that before. It helped me understand wire #9 but I didn't fully understand the diagram which is why I asked what wires #10, #11 &#18 do

Edit, still trying to copy factory as much as possible but using wire #9 will result in too much voltage drop so I'll make a circuit for battery charging on my bussman box

 

#18 is from tow relay pin 87 (power to tow battery)#10 & #11 are the combined turn/stop left n right from converter.

 

Which one of them is for the backup lamp?

 

Most of your questions can be answered by Caribe post.

BE1 pin 7 Supplied from the below. The same circuit as the reverse lights in the tail lights. So tapping into the taillights like I did isn't going to matter, plus it was convienent for me. If you're worried about too much draw you can use the feed to trigger a relay.

 

Yes..Duplicate a 2013 circuit with larger wiring.