DRSMPS wrote:
I would start at the 7-way connector and start following the wires back on the trailer. You'll likely run into several junction points which are corroded or loose. If you use your tester at each connection point, you'll soon find the faulty point in the circuit.
Frustrating - I know. Kind of like finding the loose bulb on your Christmas lights!
Good luck.
A couple days after bringing our camper home, I had this issue. Turned out to be a couple of loose, wire nutted splices in the first (and only, as far as I know) junction box as described in the above post. Seems they tied too many wires together in each splice for most any wire nut to really secure properly. No way I could break them up into smaller bundles without adding a second box. I just redid the splice, but I'll know where to go if it happens again.