My SUV has a 4pole harness so I bought this adapter to convert to a 5pole
http://www.etrailer.com/tv-wir....aspx

There is not much to the harness, you just plug it into your 4 pole and wire up the blue wire to the reverse light using a scotchlock.

I tested everything after wiring it up by starting the car and using a test lead
White - Ground
Brown - Constant on
Yellow - Constant on - intermittent when signaling right
Green - Constant on - intermittent when signaling left
Blue - Turns on when I put the car in reverse

After testing everything without the trailer hooked up I turn off the car and plug her in. Now here's where the problem starts.

As soon as I turn on the car the display panel shows a VMS error. If I step on the brakes it tricks the car into thinking that it is in reverse - the reverse light comes on in the dash, the backup camera turns on, and the reverse lights on the car engage.

The Trailer lights don't turn on, but the reverse lights on the trailer turn on if I step on the brakes just like the car.

What could be going wrong. I just picked up the boat 2 weeks ago and haven't towed it. My buddy plugged in with his Nissan Titan last weekend and everything appeared to be working fine.