I have a 2007 ford e-250 and need to wire it for a boat trailer,I checked hoppy mate and they don`t have the plug in harness that my 1997 van had and they said you have to splice into the harness,what wires go to what in the harness to the trailer plug?thanks for your help.

 

The plug for trailer lights is on the driver's side frame rail just behind the rear axle. the pigtail that fits this plug is over $100 from the dealer , so most people just buy a plug and splice it in. I don't have the colors handy but if you search this forum you should find it.