2005 Freightliner Trailer Connector Question

[suprstreet]

Have a 2005 Itasca Meridian 39' on Freightliner diesel pusher chassis. My boat trailer uses the backup light pin (middle pin on 7 pin connector) to unlock the hydraulic brakes when backing.
My backup lights work but the center pin gets no power, want to see if there is some systemic change to get it to work vs chasing down the wiring loom. Upon visual all the wiring looks like it's there and all the other pins except trailer brakes have power (no electronic brake controller attached right now).

[emiddleb]

There is a hidden fuse block in the back of your coach which has fuses for the tow hitch. One of those is a 10amp fuse for the backup lights. Perhaps it's blown. The fuse block is fun to find, on some it's in the very last bay next to the side radiator, on others its behind a screw panel in the electrical bay. You might have to do some Google work and looking around for your particular RV, as its installed differently depending on make/model, but its always at the back drivers side. I think I've read that on a 05 Meridian it's near the cable TV hookup in the bay.

[suprstreet]

I found the relay panel for the trailer connector, in the electrical bay.
There is no power to the backup fuse (all the other fuses have power) so now I'm pulling the relay panel to see if there's a poor or no connection.

[suprstreet]

I didn't find anything wrong with the relay/fuse block there must be something systemic not allowing power to the backup light connector wiring. I'm going to put in a trailer brake controller so we'll see if that gets power to the backup light trailer connector system.