2020 Freightliner M2 106 – Fuse Box Diagram & Amperage

Quick Answer

The 2020 Freightliner M2 106 typically has multiple fuse box locations to manage the complex electrical systems of a medium-duty truck. You'll primarily find fuse boxes in the following locations:

• Under-hood: Usually located on the driver's side, often near the firewall or battery box, containing fuses and relays for major engine and high-current systems.
• Interior (Dash Kick-Panel): Often found behind a removable panel on the driver's side kick panel or a glove compartment, controlling cabin accessories and lower-current circuits.
• Rear-mount chassis/Battery box: In some configurations, especially those with custom bodies or additional accessories, secondary fuse panels may be located as part of the battery box or on the chassis rail at the rear of the cab/front of the body for trailer and accessory power.

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Under-hood Fuse Box

The under-hood fuse box on your 2020 Freightliner M2 106 is the primary distribution point for many critical high-amperage circuits and relays, including those for the engine control module (ECM), ignition, fuel pump, and various lighting. This box is typically located on the driver's side under the hood, often near the steering column base or firewall. Always refer to the fuse legend inside the lid of your specific vehicle, as configurations can vary based on options and engine type.

Relays in the Under-hood Box:

• Starter Relay: Engages the starter motor.
• Fuel Pump Relay: Controls power to the fuel pump.
• ECM Power Relay: Supplies power to the Engine Control Module.
• Headlight Relays (High/Low Beam): Control the headlight circuits.
• ABS Main Relay: Powers the Anti-lock Braking System.
• HVAC Blower Relay: Controls the main blower motor power.

Fuse #	Amp	Color	Circuit / Component Protected
F1	20A	Yellow	ECM / PCM Power
F2	15A	Blue	Fuel Pump Relay Control
F3	30A	Green	Ignition Main Relay Power
F4	25A	Clear	Starter Solenoid / Relay Control
F5	10A	Red	ABS Module Power (Main)
F6	15A	Blue	Headlight Low Beam - Left
F7	15A	Blue	Headlight Low Beam - Right
F8	15A	Blue	Headlight High Beam - Left
F9	15A	Blue	Headlight High Beam - Right
F10	20A	Yellow	HVAC Blower Motor Main Power
F11	10A	Red	A/C Clutch Relay Control
F12	10A	Red	Trailer Marker Lights
F13	20A	Yellow	Auxiliary Power Outlet / Cigar Lighter (Chassis)
F14	5A	Tan	Interior Cabin Fuse Box Feed (Control)

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Interior (Dash Kick-Panel) Fuse Box

The interior fuse box, often located behind a removable panel on the driver's side kick panel or sometimes in the glove compartment area, manages electrical systems within the cab. These circuits include the radio, interior lighting, accessory power outlets, and other convenience features. Access typically involves removing a small plastic cover.

Relays in the Interior Box (if applicable):

• Accessory Relay: Controls power to various non-essential cabin accessories.
• Blower Motor Relay (Low Current): For lower fan speeds or accessory circuits.
• Radio Power Relay: Supplies switched power to the infotainment system.

Fuse #	Amp	Color	Circuit / Component Protected
F1	10A	Red	Radio / Infotainment Head Unit
F2	20A	Yellow	Power Outlet / Cigar Lighter (Cab)
F3	15A	Blue	Blower Motor (Lower Speeds)
F4	5A	Tan	Instrument Cluster
F5	10A	Red	Interior Lighting
F6	10A	Red	Wiper Motor
F7	15A	Blue	Turn Signals / Hazard Lights
F8	15A	Blue	Brake Lights
F9	10A	Red	ABS Indicator Light
F10	20A	Yellow	Trailer Brake Controller Power

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Rear-Mount Chassis / Battery Box Fuse Panel

Depending on the body upfitter and specific configurations (especially for commercial applications with custom bodies or towing packages), your M2 106 may have an additional fuse panel located on the chassis, often near the batteries or at the rear of the cab. This panel typically handles power distribution for trailer wiring, auxiliary equipment, and specialized body functions. Always verify its presence and exact location.

Relays in the Rear-Mount Panel (if applicable):

• Trailer Brake Relay: For electric trailer brake systems.
• Auxiliary Power Relays: For any added equipment.

Fuse #	Amp	Color	Circuit / Component Protected
F1	30A	Green	Trailer Brake System Main Power
F2	20A	Yellow	Trailer Aux Power (Charge Line)
F3	15A	Blue	Trailer Tail / Marker Lights
F4	20A	Yellow	Auxiliary Upfitter Equipment (Switched)
F5	10A	Red	Auxiliary Upfitter Equipment (Constant Power)

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How to Test a Fuse

Testing a fuse is a straightforward process that can help diagnose electrical issues. Here's how you can do it:

1. Safety First: Ensure the vehicle's ignition is off and the parking brake is engaged before working with electrical components.
2. Locate the Fuse Box: Find the relevant fuse box for the circuit you're troubleshooting.
3. Identify the Suspect Fuse: Consult the fuse diagram (usually printed on the fuse box lid or in your owner's manual) to locate the fuse for the problematic component.
4. Visual Inspection: Most automotive fuses are clear plastic, allowing you to visually check the metal filament inside. If the filament is broken or burned, the fuse is blown.
5. Use a Fuse Tester or Multimeter:
   • Fuse Tester: A simple tool with a light that illuminates if the fuse is good. Touch the probes to the small metal test points on top of the fuse (without removing it). Test both sides. If both light up, the fuse is good. If only one or none light up, it's blown.
   • Multimeter: Set your multimeter to the continuity or ohms setting. Carefully remove the suspect fuse. Touch the multimeter probes to each metal blade of the fuse. A good fuse will show very low resistance (near 0 ohms) or beep if on continuity mode. A blown fuse will show infinite resistance (open circuit) and won't beep.
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

On a workhorse like the Freightliner M2 106, certain fuses tend to experience more stress due to their continuous operation or exposure to varying conditions. When a component stops working, checking its fuse is always the first step. Here are some commonly blown fuses:

• Cigar Lighter / 12V Power Outlets (F13 Under-hood, F2 Interior): These fuses often blow due to overloading from charging multiple devices, using high-power accessories, or short circuits in connected devices.
  • What to check first: Disconnect all devices from the outlets before replacing the fuse. Test the outlet with a known good, low-power device.
• Blower Motor (F10 Under-hood, F3 Interior): A failing blower motor, a clogged cabin air filter, or an obstruction in the blower fan can cause the motor to draw too much current, blowing its fuse.
  • What to check first: Ensure the cabin air filter is clean. Listen for any unusual noises from the blower motor. If the fan runs heavily or smells burnt, the motor itself may be failing.
• Headlights (F6, F7, F8, F9 Under-hood): While less common without an impact, a short in the wiring or a faulty bulb can sometimes cause a headlight fuse to blow. If only one headlight is out, it's more likely the bulb; if multiple lights or both sides are out, check the fuses and relays.
  • What to check first: Visually inspect the headlight bulbs. If a bulb looks burnt out, replace it first before checking fuses.
• Trailer Brake Controller (F10 Interior, F1 Rear Chassis): Issues with trailer wiring, shorts in the trailer's electrical system, or an overloaded trailer brake controller can easily blow these fuses.
  • What to check first: Inspect the trailer's wiring harness for any damage or corrosion. Unplug the trailer before checking/replacing the fuse. Test the truck's trailer connector for proper voltage.

Always remember to check the fuse box legend for your specific vehicle configuration. These are general guidelines, and your M2 106 might have slight variations.

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