Tekonsha T-One® T-Connector Harness 4-Way Flat Trailer Wiring Kit - Compatible with Toyota Sienna & Other Vehicles - Perfect for Towing Trailers, Boats & Campers

This wiring harness comes with detailed instruction, so even if you have never done anything like this before, it is extremely easy to install. The instruction says that you need to run the main power wire to the battery underneath of the vehicle and avoid contact with hot or moving parts. Instead, I ran the main power wire inside the van under plastic side panels and moldings on the floor, so the wire will not be exposed to elements, water, snow, ice, salt etc. It was easy ho hide the wire without removing any panels inside, except for the rear panel in the trunk because you need to run the wire from the right to the left taillight. The main obstacle is to get the wire through the fire wall to the engine compartment, but there are some grommets that you can stick the wire through and that's what I did. It is plug-and play thing, so no modifications or splicing the existing wires is needed. It took me about 2 hours but I took my time. The only one thing that I want to make you aware of is that the length of the main power cable included with the kit is just enough to go to the front of the vehicle if you run it underneath. I ran mine inside, so I had to add about 2 feet of wire and I used a but connector and some heat shrink to extend it. It works well and I would highly recommend this product!