I have a 2004 Dmax. This truck is new to me. When I put my camper on for the weekend, I noticed the truck was not charging the batter in the camper. I checked pin 4 of both the truck camper harness & the trailer harness. No juice. The manual does not seem very helpful in identifying the fuse or breaker involved. Someone suggested that if the batteries in the truck are up to par & fully charged, nothing will appear there anyway.