2017 Kenworth W900 Fuse Box Diagram, Locations & Amperages

As an ASE-certified master technician, I know that keeping a heavy-duty workhorse like the 2017 Kenworth W900 on the road means staying on top of electrical maintenance. Modern Class 8 trucks utilize complex multiplexed electrical systems, and a simple blown fuse can take down critical systems like your ECM, headlights, or trailer brakes.

Below is a comprehensive guide to the fuse box locations, standard configurations, and amperage ratings for the 2017 Kenworth W900.

Disclaimer: Kenworth builds trucks to custom specifications. Your W900’s exact wiring may vary based on engine choice (Cummins vs. PACCAR), sleeper configuration, and dealer-installed options. Always verify with the printed legend on your fuse box lid.

Quick answer

On a 2017 Kenworth W900, the fuses and relays are distributed across three primary locations:

1. Main Cab Fuse Panel (Dash/Kick Panel): Located behind the clutch pedal on the driver's side kick panel, or behind the lower dash trim panel. This controls interior electronics, lighting, and HVAC.
2. Under-Hood Power Distribution Center (PDC): Located on the driver's side firewall under the hood. This manages high-amperage powertrain components like the ECM, starter relay, and ABS.
3. Sleeper Fuse Panel (If Equipped): Located under the bunk or behind the driver-side sleeper access door. This controls auxiliary sleeper components like the fridge, sleeper HVAC, and interior bunk lighting.

---

Main Cab Fuse Panel (Dash / Kick Panel)

The main cab fuse box is located inside the cabin, usually behind a removable panel down by the driver’s left foot or lower dashboard. This box manages the bulk of the driver-operated accessories and cab lighting.

Fuse #	Amp	Color	Circuit / Component Protected
F1	15A	Blue	Headlights (Low Beam - Left/Right)
F2	15A	Blue	Headlights (High Beam - Left/Right)
F3	10A	Red	Radio / Infotainment / CB Power
F4	20A	Yellow	Cab HVAC Blower Motor
F5	10A	Red	Instrument Cluster / Gauges
F6	15A	Blue	Turn Signals / Hazard Flasher
F7	15A	Blue	Windshield Wipers / Washers
F8	20A	Yellow	12V Cigar Lighter / Power Outlets
F9	10A	Red	Interior Dome Lights / Map Lights
F10	15A	Blue	Stop / Brake Lights
F11	20A	Yellow	Power Windows / Door Locks
F12	10A	Red	Airbag / SRS Module
F13	15A	Blue	Horn / Air Horn Solenoid
F14	10A	Red	Ignition Switch / Key ON Power
F15	10A	Red	A/C Compressor Clutch

Note: You will also find various micro-relays in this panel for the blower motor, wiper motor, and headlight circuits.

---

Under-Hood Power Distribution Center (PDC)

The under-hood fuse box is mounted on the driver's side firewall. This box protects the engine management system, chassis electronics, and high-draw systems.

Fuse #	Amp	Color	Circuit / Component Protected
1	30A	Green	Engine Control Module (ECM / PCM) Battery Power
2	20A	Yellow	Engine Control Module (ECM) Ignition Power
3	30A	Green	Starter Motor Relay / Solenoid
4	20A	Yellow	Fuel Pump / Fuel Heater System
5	30A	Green	Tractor ABS / Bendix Module
6	30A	Green	Trailer ABS Power (Blue Wire on 7-way)
7	30A	Green	Trailer Auxiliary / Brake Controller
8	20A	Yellow	NOx Sensor / DEF System Power
9	15A	Blue	Transmission Control Module (TCM - Automatics)
10	20A	Yellow	Heated Mirrors / Mirror Defrost

Key Relays Located Here: Starter Relay, ECM Power Relay, Fuel Heater Relay, and Trailer Marker Lamp Relay.

---

Sleeper Fuse Panel (If Equipped)

For W900s equipped with an Aerocab or Studio Sleeper, an auxiliary fuse block handles the sleeper compartment. It is typically accessed under the bunk or via a lower side compartment.

Fuse #	Amp	Color	Circuit / Component Protected
S1	20A	Yellow	Sleeper HVAC Blower Motor
S2	15A	Blue	Sleeper Dome & Reading Lights
S3	20A	Yellow	Refrigerator Power
S4	30A	Green	Power Inverter (Primary Circuit)
S5	15A	Blue	12V Auxiliary Sleeper Outlets
S6	10A	Red	Sleeper Radio / TV Prep

---

How to test a fuse

When an electrical component fails on the road, testing fuses is the first step. Here is the proper way to check them:

1. Safety First: Turn off the ignition key, set your parking brakes, and turn off all electrical accessories.
2. Visual Inspection: Pull the suspect fuse using fuse pullers or needle-nose pliers. Look at the U-shaped wire inside the plastic housing. If it is broken, melted, or blackened, the fuse is blown.
3. Use a Multimeter or Test Light (Best Method): Sometimes a fuse looks fine but has a hairline crack. Set a digital multimeter to the continuity or ohms setting. Touch a probe to each metal leg of the fuse. A beep or a reading close to 0.0 ohms means the fuse is good. O.L. (Open Line) means it is bad.
4. Testing in the Panel: You can also clip a 12V test light to a good chassis ground and touch the small metal testing tabs on the top of the fuse while it is plugged in (and the circuit is powered). If it lights up on one side but not the other, the fuse is blown.
5. Replacement: Always replace a blown fuse with the exact same amperage and color. Putting a 30-amp fuse in a 10-amp slot can cause wiring to overheat and potentially start a fire.

---

Common blown fuses on this vehicle

Based on my experience working on Kenworth heavy-duty trucks, these are the most frequent offenders you'll encounter on the 2017 W900:

• Trailer ABS / Trailer Auxiliary Power (Under-Hood F6/F7): The 7-way pigtail cord between the tractor and trailer takes a lot of abuse. Corrosion inside the plug or a shorted wire on a poorly maintained trailer will frequently pop the 30-amp trailer fuses. Always inspect your pigtail and the trailer's receptacle before just replacing the fuse.
• 12V Cigar Lighter / Outlets (Cab F8): Drivers plug in a lot of heavy-draw accessories like coffee makers, phone chargers, or coolers. Overloading these circuits will easily snap the 20A fuse.
• Cab or Sleeper HVAC Blower (Cab F4 / Sleeper S1): Blower motors pull high amperage, especially as they age and the bearings wear out. If your A/C or heat suddenly stops blowing, check this fuse. If it keeps blowing, the blower motor or the resistor likely needs replacement.
• DEF / NOx Sensor Power (Under-Hood F8): The emissions system wiring runs down the frame rail near the hot exhaust. Wiring can chafe or melt, shorting out the NOx sensor or DEF doser power supply.

If a replacement fuse blows immediately after you install it, do not keep putting new fuses in. You have a direct short to ground in the wiring or the component itself.

If you are dealing with a recurring electrical issue or multiplex wiring problem that you cannot track down, it’s best to get professional help. Find a trusted shop on Repairius.