imported post
This wiring harness will let you just unplug the plugs to your back lights and the just plug this harness in without cutting any wires. It is $16.00:
http://www.cyclemaxohio.com/inc/sdetail/195
We then bought an adapter/Isolator from uhaul for $39.95. This was needed because the Goldwing uses separate turn signals and brakes and our trailer used a common bulb for turn signals and brakes with a flat 4 connector. It also gets its power directly from the battery so if there is a problem with the trailer lights it doesn't bring the bike down:
http://store.uhaul.com/product_detail.aspx?id=4074