2025 Kenworth T680 Fuse Box Diagram & Amperage

Quick answer

The 2025 Kenworth T680 typically has three primary fuse box locations: one under the hood, one behind the passenger kick panel (dashboard area), and one in the sleeper compartment (sometimes referred to as the "trunk" or "rear" fuse box due to its location).

It is crucial to always verify the exact fuse layout against the printed legend inside your specific vehicle's fuse box cover, as configurations can vary based on trim levels and optional equipment.

Under-Hood Fuse Box

This fuse box primarily handles high-current circuits and critical powertrain functions. Relays for the engine, starter, and other heavy-duty components are also typically found here.

Common Relays in this box include: Starter Relay, ECM Power Relay, Fuel Pump Relay, Headlight Relays.

Passenger Kick Panel Fuse Box (Dash)

Located behind the passenger side kick panel, this fuse box handles many of the cabin accessories and lower-current systems.

Common Relays in this box include: Accessory Delay Relay, HVAC Blower Speed Relays, Interior Lighting Relay.

Sleeper Compartment Fuse Box (Trunk/Rear)

This fuse box powers the electrical components in the sleeper area, including additional power outlets, lighting, and sometimes auxiliary HVAC systems.

Common Relays in this box include: Sleeper Power Relay, Auxiliary HVAC Relay.

How to test a fuse

Testing a fuse is a straightforward process. First, ensure the ignition is off. Locate the fuse box you need to check and remove its cover. Each fuse typically has two small metal contact points on its top. You can use a fuse puller (often found in the fuse box lid or with the vehicle's tool kit) to remove the fuse you suspect is blown.

There are two main ways to test a fuse:

1. Visual Inspection: Most automotive fuses are clear, allowing you to see the small wire filament inside. If the filament is broken or charred, the fuse is blown and needs replacement.
2. Using a Multimeter or Test Light: For a more accurate test, set your multimeter to the continuity setting. Touch one probe to each metal contact point on the top of the fuse. If the multimeter beeps or shows a reading close to zero ohms, the fuse is good. If there's no beep or an "OL" (open loop) reading, the fuse is blown. Alternatively, a 12V test light can be used. With the ignition on, touch the tip of the test light to each metal contact point on the top of the fuse. If both sides light up, the fuse is good. If only one side lights up or neither lights up, the fuse is blown.

Always replace a blown fuse with a new one of the exact same amperage rating and type. Using a fuse with a higher amperage can lead to electrical system damage or fire.

Common blown fuses on this vehicle

While the 2025 Kenworth T680 is built for durability, certain fuses are more susceptible to blowing due to common issues or heavy usage:

• Cigar Lighter/12V Outlets (F21, F40): These fuses frequently blow due to over-Gunging devices, using faulty chargers, or short circuits in connected accessories. If your phone charger or other portable device isn't working, check these first.
• Headlights (F5, F6, F7, F8): While less common with modern LED lighting, a short circuit in the wiring or an issue with the bulb assembly itself could cause a headlight fuse to blow. If one or both headlights are out, check these fuses.
• Trailer Brake Control (F10): Given the nature of a heavy-duty truck, connecting trailers with electrical issues can cause this fuse to blow. If you lose power to your trailer brakes, this is a prime suspect.
• Radio/Infotainment (F20): Aftermarket installations or issues with the truck's entertainment system can sometimes lead to this fuse blowing. If your radio or display unit is dead, check F20.
• Blower Motor (F12): A failing blower motor or an obstruction in the fan can draw excessive current, causing its fuse to blow. If your HVAC fan isn't working on any setting, this fuse should be checked.

When a fuse blows, it's important to not just replace it, but to also investigate why it blew. A recurring blown fuse indicates an underlying electrical problem that needs professional diagnosis.

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