If I am seeing your picture correctly that is "off" on my Seneca. When toggled "up" on mine it lights up and works well.
Unsure of fuse location too, since we have a multiplexed electrical system and the EB is a "smart" switch it may be something Freightliner needs to diagnose.
2014 Seneca 37TS
Toads: 2014 Ford Explorer Sport or 2013 Ford Focus ST