2019 Freightliner Cascadia (New Gen model), trailer light issues are often controlled by the system rather than traditional fuses. Unlike older models that had a dedicated black fuse box on the driver-side firewall, the 2019 model typically uses Field Effect Transistors (FETs) that electronically shut off and reset once a short is cleared. Primary Locations to Check
Often a black or red box located near the steering rod or washer reservoir. Power Distribution Module (PDM):
Depending on the specific lighting issue, you should check these locations: Module Location Specific Identifiers SAM Chassis (Engine Bay) Relay R9 and Fuse 13 Trailer Stop/Tail Trailer PDM / SAM Cabin Varies; check labeling on the lid Trailer Turn Signals SAM Chassis Relays R3 (Left) and R4 (Right) Trailer Auxiliary Power SAM Cabin (Dash) Fuses 61A and 61B Trailer ABS Passenger Side Fuse Box Fuses F43, F25, and F26 Freightliner Cascadia Trailer Light Fuse Location - Q&A 2019 freightliner cascadia trailer light fuse location
Located under the passenger-side dash cover or beneath the passenger seat. This panel contains high-amp fuses and main power relays. Troubleshooting Common Light Issues New 2019 Freightliner Cascadis Truck Fuse & Relay Location
On many 2019 models, the trailer light circuits are computer-controlled. If there is a short in the trailer wiring, the system "trips" the circuit internally. Instead of replacing a blown fuse, you often just need to fix the short and cycle the key If there is a short in the trailer
The SAM modules use "virtual fuses." If there is a short in your trailer wiring, the module may temporarily disable that circuit. In some cases, turning the truck off and on (key-cycle) resets the circuit, but if the issue persists, a dealer may need to perform a software reset .
If your trailer brakes are not illuminating when you press the pedal: but if the issue persists
You are on the side of the highway and don't have spare fuses. Look at your PDM box. Freightliner usually includes a (10A, 15A, 20A) clipped into the inside of the PDM lid.