If you are still looking for physical fuses or relays, check these three main areas:
2019 Freightliner Cascadia , the trailer light "fuse" location is actually a shift in technology from older models. Instead of a traditional dedicated fuse box on the driver-side firewall, this model often uses the SAM (Signal Detect and Actuation Module) Chassis systems to manage trailer power. The Story of the "Missing" Fuse Box 2019 freightliner cascadia trailer light fuse location
If you check fuses 60, 61, and 62 and they are all fine, but your trailer still has no lights, look for a labeled Fuse #1 (usually 30 or 40 Amp). If you are still looking for physical fuses
The trailer light fuse on a 2019 Freightliner Cascadia is typically located in the fuse box, which can be found in the engine compartment. Specifically, you should check: The trailer light fuse on a 2019 Freightliner