2022 Freightliner Cascadia — Fuse Box Diagram & Amperage

Quick answer

• Under-hood: Chassis Power Distribution Module (PDM) on the left/front bulkhead area (ahead of the driver’s side), houses fuses and relays for headlights, ABS feed, engine/A/C clutch, trailer lighting, etc.
• Dash/kick-panel: Cab PDM (fuse/relay panel) behind the right dash service panel/kick panel; protects cab electronics like radio/infotainment, cigar/12V outlets, blower motor, HVAC controls, wipers, instrument cluster, and ignition feeds.
• Sleeper/Battery box (cargo equivalent): Powernet Distribution Box (PNDB) inside/adjacent to the left-frame battery box and a small sleeper fuse block (if equipped) under the lower bunk; contains main JCASE/MEGA fuses for ECM/PCM, starter feed, cab PDM feed, trailer charge/brake controller feed, bunk HVAC and power outlets.

Note: Freightliner assigns slightly different fuse positions by VIN, engine (DD13/DD15), sleeper package, and options. The layouts below reflect the most common 2018–2022 New Cascadia configuration. Always confirm against the printed legend inside each fuse box cover.

Under-hood Chassis PDM (left/front bulkhead)

Typical blade/JCASE fuses in this box:

Common relays in this box:

• Headlamp Low relay, Headlamp High relay
• A/C Clutch relay
• ABS Pump/Feed relay (varies by build)
• Trailer Stop/Marker relays
• Engine Run/IGN relay (wake)

Dash/Kick-panel Cab PDM (right dash service panel)

Typical mini-fuses and micro-relays for cab loads:

Relays in this panel commonly include:

• Blower Motor relay (low/high)
• IGN Run/Accessory relay (cab feed)
• Wiper High/Low relays
• Radio power relay (varies by option)

Sleeper/Battery Box PDMs (PNDB and Sleeper fuse block)

Powernet Distribution Box (PNDB) near/inside the battery box carries high-current JCASE/MEGA fuses; many sleeper units also have a small fuse panel under the lower bunk.

Relays at/near PNDB and sleeper block (varies by build):

• Starter relay (often integrated in PNDB or adjacent bracket)
• Bunk HVAC blower relay
• Trailer charge/aux relay

Important: Exact PNDB labeling differs by engine/emissions package; verify the molded map on the PNDB cover.

How to test a fuse

• Visual check: Remove the suspect fuse and look for a melted link. Not all failures are obvious, so use a meter.
• Test light method: Key ON for ignition-fed circuits. Probe the two small test tabs on top of the fuse. A good fuse lights the probe on both tabs; power on one tab only means the fuse is blown. No power on either tab? The circuit may be off or the feed is upstream.
• Multimeter continuity: With the fuse removed, a good fuse shows near 0 Ω. Infinite/open = blown.
• Load verification: After replacing a blown fuse with the same amperage and color, operate the circuit while monitoring. If it blows again, chase shorts at connectors, chafed harness points, and the component itself before upsizing the fuse (never increase fuse rating).

Common blown fuses on this vehicle (what to check first)

• 12V outlets (F31/F32, 20A yellow): Portable coolers, CB radios, and chargers can short at the plug. Inspect the socket for coins/debris and bent contacts before replacing the fuse.
• Headlamp fuses (F1–F4, 15A blue): Bulb failures or moisture in the headlamp housing. Check for water intrusion and bulb harness condition.
• Blower motor (F37, 30A green): Seized blower or melted connector at the resistor/control module. Spin the blower by hand and check current draw; verify the blower relay is not heat-damaged.
• A/C clutch (F11, 10A red): Clutch coil shorting when hot. Measure coil resistance; inspect clutch gap and relay contacts.
• ABS feed (F13/M4): Look for rubbed harness at frame clips near the drive axles and trailer pigtail shorts.
• Trailer lighting (F7, F21, 20A yellow): Most repeat failures trace to a shorted trailer harness or lamp. Test with a known-good trailer or a 7-way tester before condemning the truck.
• ECM/IGN feed (F15/M9): After improper jump-starts, the ECM feed JCASE can open. Confirm battery grounds, alternator output, and clean PNDB connections.
• Sleeper outlets/blower (S1/S3): Inverters and bunk appliances overload outlets; verify appliance current draw and wiring condition under the bunk.

Final tips

• Freightliner often groups multiple downstream circuits behind a relay in the PDMs. If a new fuse pops instantly, swap-test the relay and inspect the harness section that moves (hood hinge, cab-to-frame, and bunk tilt points).
• The most reliable identifier is the fuse/relay legend printed inside each box lid. Use it to confirm positions before pulling parts.

Find a trusted shop on Repairius.