2025 Kenworth W900 Fuse Box Diagram & Amperage

Quick Answer

The 2025 Kenworth W900 typically features three main fuse box locations:

• Under-Hood Power Distribution Center: Located on the driver's side, near the firewall.
• In-Cab Fuse Panel (Driver's Side Kick Panel): Behind a removable panel on the driver's side kick panel.
• Sleeper/Mid-Chassis Fuse Panel: Often found in the sleeper compartment or a mid-chassis service compartment, depending on the cab configuration.

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Under-Hood Power Distribution Center

The under-hood power distribution center houses many of the high-amperage fuses and relays essential for major vehicle systems like the ECM, fuel pump, headlights, and starter. Always refer to the specific fuse legend on the underside of your fuse box lid for exact fuse identification, as configurations can vary slightly.

Fuse #	Amp	Color	Circuit / Component Protected
F1	10A	Red	ECM/PCM Main Power
F2	15A	Blue	Engine Ignition
F3	20A	Yellow	Fuel Pump
F4	30A	Green	Starter Relay Control
F5	20A	Yellow	ABS Controller Main Power
F6	15A	Blue	Low Beam Headlight (Left)
F7	15A	Blue	Low Beam Headlight (Right)
F8	20A	Yellow	High Beam Headlight (Left)
F9	20A	Yellow	High Beam Headlight (Right)
F10	10A	Red	A/C Clutch
F11	30A	Green	Blower Motor (Main)
F12	20A	Yellow	Trailer Brake Control (Main)
F13	10A	Red	Transmission Control Module (TCM)
F14	20A	Yellow	Auxiliary Power Outlet (Main)
F15	10A	Red	Airbag System

Relay Locations (Common):

• R1: Starter Relay
• R2: Fuel Pump Relay
• R3: Headlight Relay (Low Beam)
• R4: Headlight Relay (High Beam)
• R5: Blower Motor Relay
• R6: A/C Clutch Relay

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In-Cab Fuse Panel (Driver's Side Kick Panel)

This fuse panel primarily handles interior accessories, lighting, and convenience features. Access it by removing the trim panel on the driver's side kick panel.

Fuse #	Amp	Color	Circuit / Component Protected
F1	10A	Red	Radio/Infotainment System
F2	15A	Blue	Cabin Interior Lights
F3	10A	Red	Instrument Cluster
F4	20A	Yellow	Cigar Lighter / 12V Power Outlet
F5	15A	Blue	Wiper Motor
F6	10A	Red	Turn Signals / Hazard Lights
F7	10A	Red	Brake Lights (Stop Lamps)
F8	15A	Blue	Park/Tail Lights (Left)
F9	15A	Blue	Park/Tail Lights (Right)
F10	20A	Yellow	Power Windows
F11	20A	Yellow	Auxiliary Switches (Cab)
F12	10A	Red	HVAC Control Panel
F13	15A	Blue	Mirror Heaters
F14	10A	Red	Diagnostic Port (OBD-II/J1939)
F15	5A	Tan	ABS Warning Light

Relays (Common):

• R1: Accessory Delay Relay
• R2: Wiper Control Relay
• R3: HVAC Blower Speed Relay (Lower Speeds)

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Sleeper/Mid-Chassis Fuse Panel

Depending on the W900's configuration, a third fuse panel often services the sleeper compartment's amenities, trailer connections, and other chassis-mounted systems. This can be located inside the sleeper or in an external, weather-sealed compartment.

Fuse #	Amp	Color	Circuit / Component Protected
F1	20A	Yellow	Sleeper HVAC Blower
F2	15A	Blue	Sleeper Interior Lights
F3	20A	Yellow	Sleeper Power Outlet (12V)
F4	10A	Red	Refrigerator Power (Sleeper)
F5	15A	Blue	Trailer Marker Lights
F6	15A	Blue	Trailer Auxiliary Power
F7	20A	Yellow	Trailer ABS Power
F8	10A	Red	Auxiliary Heater Control (Sleeper)
F9	15A	Blue	Inverter Power (Main - if equipped)
F10	10A	Red	ECM/PCM Auxiliary Power

Relays (Common):

• R1: Sleeper HVAC Blower Relay
• R2: Trailer Auxiliary Power Relay

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How to Test a Fuse

Testing a fuse is a straightforward process and requires a simple tool: a fuse tester or a multimeter. Here's how:

1. Safety First: Ensure the vehicle's ignition is off before removing or inserting fuses. Disconnect the battery for added safety when working with the under-hood panel.
2. Locate the Fuse: Consult your vehicle's owner's manual or the fuse box lid diagram to identify the suspicious fuse.
3. Visual Inspection: Many fuses have a visible wire element inside. If this wire is broken or charred, the fuse is blown. However, not all blown fuses are visually obvious, especially the smaller mini-fuses.
4. Remove the Fuse: Use the plastic fuse puller typically found in your fuse box or a pair of needle-nose pliers to gently pull the fuse straight out.
5. Test with a Multimeter:
   • Set your multimeter to the "ohms" (Ω) setting, or the continuity setting (which often beeps if there's continuity).
   • Touch one probe to each metal blade of the fuse.
   • If the multimeter displays a reading close to zero ohms or beeps (for continuity), the fuse is good.
   • If the multimeter displays "OL" (open circuit) or no reading/no beep, the fuse is blown.
6. Replace (If Blown): If the fuse is blown, replace it with a new fuse of the exact same amperage rating and type. Using a fuse with a higher amperage can lead to serious electrical damage or fire.

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Common Blown Fuses on This Vehicle

While any fuse can blow, some are more prone to failure due to the circuits they protect or common usage patterns. For the Kenworth W900, common culprits might include:

• Cigar Lighter / 12V Power Outlets: Often overloaded by high-draw accessories like phone chargers, power inverters, or portable refrigerators. If your charging ports aren't working, check this first.
• Headlight Fuses: Especially if you frequently drive at night or experience bulb failures, a short in a headlight circuit can blow its fuse.
• Trailer Brake/Auxiliary Power Fuses: Constant use, corrosion in trailer wiring, or issues with connected trailers can cause these to blow. If your trailer lights or brakes aren't working, these are key fuses to inspect.
• Blower Motor Fuse: A failing blower motor or obstructions in the HVAC system can draw excessive current and blow the fuse. If your fan isn't working on any speed, start here.
• Radio/Infotainment Fuse: Aftermarket installations, shorts within the unit, or even a disconnected wire can cause this fuse to pop. If your radio is dead, check this fuse.

What to check first: Before automatically replacing a blown fuse, consider what was in use when the fuse blew. Did you plug in a new device? Did a light stop working? Identifying the cause can prevent the new fuse from blowing immediately as well. Always check the easiest-to-access fuse boxes first (in-cab, then under-hood).

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