2023 Freightliner Cascadia: Fuse Box Diagram & Amperage

Quick answer

On the 2023 Freightliner Cascadia, you will find two primary fuse and relay centers:

• SAM Chassis Module: Located inside the cab on the passenger side, behind a kick panel in the footwell.
• Power Distribution Module (PDM) / Mega Fuse Box: Located under the hood, typically on the driver's side near the firewall.

Always consult the printed legend on the inside of your fuse box covers to verify exact fuse and relay locations, as they can vary based on your truck's specific configuration and options.

SAM Chassis Module (In-Cab)

The main fuse and relay center inside the cab is the SAM (Signal Detect and Actuation Module) Chassis module. It is located behind a protective panel in the passenger footwell. You may need a flathead screwdriver or a trim removal tool to access it.

This panel houses the fuses for most of the cab's electronic functions, from lights and instruments to HVAC and power outlets.

Common Relays in this Location:

• R1: Starter Relay
• R2: Ignition Main Relay
• R3: Headlight Relay
• R4: Blower Motor Relay
• R5: A/C Clutch Relay

Power Distribution Module (Under-Hood)

This heavy-duty fuse box is located under the hood, usually on the driver's side. It contains high-amperage "Mega" fuses that protect the main power feeds to various systems, including the cab itself. These are bolted-in fuses, not the pull-out type found inside the cab.

How to test a fuse

If a component has stopped working, a blown fuse is a likely culprit. You can test a fuse in two simple ways.

1. Visual Inspection: Pull the suspect fuse from its slot (use the fuse puller tool often found in the fuse box lid). Hold it up to the light. Inside the plastic body is a small metal strip. If this strip is broken or looks burnt, the fuse is blown and needs to be replaced with one of the exact same amperage rating.

2. Using a Multimeter: For a more definitive test, set your multimeter to the continuity setting (it often looks like a sound wave symbol). Touch the probes to the two metal tabs on the top of the fuse while it's still in its slot. If the multimeter beeps or reads close to zero ohms, the fuse is good. If it remains silent or reads "OL" (Open Loop), the fuse is blown.

Common blown fuses on this vehicle

• Fuse F15 or F16 (Cigar Lighter / 12V Power Outlet): This is the most common fuse to blow. It is almost always caused by a faulty or low-quality phone charger, or a device that draws more power than the circuit is designed for. Before replacing the fuse, unplug everything from the power outlets.

• Fuse F20 (Trailer Brake Control Module): If you frequently connect and disconnect trailers, a short in the trailer's wiring can cause this fuse to blow. If it blows repeatedly, have your trailer's 7-pin connector and wiring inspected for damage or corrosion.

• Fuse F8 (Blower Motor): When the HVAC fan only works on the highest setting or not at all, mechanics often check this fuse first. If the fuse is blown, it could be a sign that the blower motor itself is aging and drawing too much current, or that the blower motor resistor has failed. Simply replacing the fuse may only be a temporary fix.

Disclaimer: Fuse locations and amperage can vary by truck configuration and build date. Always verify with the diagram printed on your vehicle's fuse box cover.

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