Hooked up to my new trailer, purchased in May, to take care of some property about 15 miles away. Got everything I thought I would need and immediately noted the brakes on the trailer were not working, had been fine the last time I used it about 2 weeks ago. Could not put off the work I had scheduled so just made the trip there and back carefully. Today after I finished some other business in town I tackled the trailer to find out just what the devil was going on. Tested the truck and had current to the plug so the problem had to be in the trailer wiring. Pulled the break away switch, still no brakes. Checked the wires at the axle had continuity but still no brakes but had battery voltage. Upon closer inspection found one of the vampire clamps (solderless T-Tap self stripping quick connector) they used to splice the wires did not clamp properly, it had just lightly skinned the wire and it would make contact when I wiggled it but when voltage was applied it would go open again.
I spent the afternoon removing every vampire clamp then butt spliced and heat shrank every splice I found on the brakes. Next I will do the same for the lights. I hate vampire clamp slices with a passion, they are a bad temporary patch at best. I know manufacturers use them to speed up the production line but they are sure fail and most likely at the wrong time.
The Public Service Announcement: Get your solder, heat gun and possibly garlic if you think you need it and get the vampires out of your trailer wiring.