So I hooked the boat up for the first ride of the season and went to check the lights (truck off hazards on) and the trailer backup lights on the trailer and solenoid lockout were clicking on and off instead of the brake/turn lights. Jacked with the connections for a while to no avail. So for grins I turned the truck on and they start working. Seems like a loose ground to me, but I'm no EE, anyone know where to start?

poor ground between your truck and your trailer.

The best $5 you will ever spend: <BR> <BR><a href="http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&amp;langId=-1&amp;catalogId=10001&amp;classNum=426&amp;subdept Num=425&amp;storeNum=17&amp;productId=223090" target="_blank">http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&amp;langId=-1&amp;catalogId=10001&amp;classNum=426&amp;subdept Num=425&amp;storeNum=17&amp;productId=223090</a> <BR> <BR>This will help you determine if the problem is on the vehicle side or the trailer side. I keep one in my glove compartment. As Newty said, I would suspect a ground issue.

Thanks guys...I wish they had one for the 7 pin plug or 5 pin on the trailer.

what happens over the winter is that rust will collect on your coupler and ball, so if you have a poor ground on your trailer, they coupler/ball combo acts as the ground. As you drive, the rust and corrosion will break down and will give a better connection. Long story short, one of your two grounds or both need to be cleaned up.