In preparation for an up coming camping trip, my son was installing a back-up camera on his slide-in pickup camper. After he installed it, he could not make the camera work. So he called good old Dad! He was wiring it into the power source for his clearance lights. He said that the lights were on, but not very bright. I had him test the voltage at the light he was trying to connect to. It read 3.8 vdc. I have seen this several times on other campers. I told him that he had a bad connection somewhere on the line. Either a loose wire, or corrosion. He spent several hours tracing down the wires and finally found the culprit. It was one small corroded connector on the main ground wire. He was so happy when the camera finally came to life. (See photos) Oh, and he said later that his clearance lights were much brighter now.