The Control Unit and Harness are strongly recommended if you are going to tow anything that requires lights/brake controls. FYI, you don't have to get Honda control units, most businesses that sell trailers sell various name brands and can do the wiring for you. Anyway, the wiring for the taillights and brakes lights of the vehicle are not strong enough to carry enough power to supply the electrical on a trailer (very dim-could cause a short). The Harness connects a power source (battery) to the trailer wires. The Control Unit is connected to the vehicle wiring as well as the Harness. When you step on the brake pedal, the Control Unit senses it and allows the power to go to the proper wiring on the trailer directly from the power source, therefore you will have brighter lights on the trailer. The same for parking and turn indicators. This is worth the money. I have this set up on my 2003 Odyssey.
inside the tire change tool door located inside left after opening tailgate door
Maximum towing capacity is 3,500 pounds.
The maximum tosing capacity of the 2007 Honda Odyssey is 3500 lbs..
The maximum tosing capacity of the 2005 Honda Odyssey is 3500 lbs..
The maximum tosing capacity of the 2009 Honda Odyssey is 3500 lbs..
The maximum tosing capacity of the 2002 Honda Odyssey is 3500 lbs..
The maximum tosing capacity of the 2003 Honda Odyssey is 3500 lbs..
The maximum tosing capacity of the 2014 Honda Odyssey is 3500 lbs..
The maximum tosing capacity of the 2008 Honda Odyssey is 3500 lbs..
The maximum tosing capacity of the 2004 Honda Odyssey is 3500 lbs..
The maximum tosing capacity of the 2006 Honda Odyssey is 3500 lbs..
The maximum tosing capacity of the 2011 Honda Odyssey is 3500 lbs..