My H3 didn't come with the towing package. I'm in the market for a travel trailer and would like to get a 7 way harness hooked up. Does anyone have detailed instructions on wiring one of these up. I have the 4 way harness hooked up but like I said I would like a 7 way for a future travel trailer.

 

I went out and looked under the dash (drivers side) by the light. I found all the wires tapped up in there. I have a black ground, Blue brake, Red for auxiliary with B+, and a light blue for brake signal.

I take all those and run them to the rear (with the existing 4 wires under the rear tire) and splice them into my 7way connection correct?

 

I think that is correct, I just have the flat four connector on mine also and it didn't come with trailer tow either, but I have installed the reciever and and transmission cooler. I looked up under dash and found the brake controller wires just like yours. I wonder if there are wires hidden under the truck somewhere, I am going to go on a search this week and see.

 

Some people have found the brake signal wire behind the battery (under the hood). I looked around the other night but didn't find anything.