Chuck if you look at the
Scamp wiring diagram in the Documents center that should help you assuming no one has messed around to much with the wiring. At the point where the wiring comes into the trailer may be a good places to check the voltage. Thats inside the trailer & the wiring is hidden under the rat fur is where you will find most of the connections to the outside. On mine thats inside the passenger side front bench hatch - on the front wall of the trailer.
Scamp btw in case your unaware does have two inline fuses on their wiring - one just off the
battery and the buried under the rat fur where the wiring enters the trailer. You may need to cut the rat fur to get it pulled back enough to see all the connections. While you have it all exposed you may also want to redo some of the connections and heat shrink wrap them as I noted that on my trailer some of the connections where pretty shaky. Another place to check may be at the point your wiring harness connects to the trailer - which depending on the age of your trailer or what others have done in the past in regards to changing wiring harnesses may or may not be inside the bench in the trailer - that may be outside and all wrapped up with a cover or tape.