2021 Mercedes-Benz Sprinter – Fuse Box Diagram & Amperage

Quick Answer

The 2021 Mercedes-Benz Sprinter features multiple fuse boxes located throughout the vehicle to protect various electrical systems. You'll typically find fuse boxes in the following locations:

• Under-hood: Located in the engine compartment, usually near the battery or on the driver's side.
• Under-dash (Driver's Side): Often found behind a removable panel on the driver's side kick panel or dashboard end cap.
• Under-dash (Passenger's Side): In some configurations, a fuse box may be located behind a panel on the passenger's side kick panel or dashboard end cap.
• Cargo Area/Rear (Depending on configuration): For certain electrical components related to the cargo area or rear accessories, a fuse box might be present in the rear of the vehicle, often behind a trim panel.

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Under-Hood Fuse Box

This fuse box powers critical engine components, lighting, and major electrical systems. Always refer to the diagram on the fuse box lid for the most accurate information for your specific Sprinter configuration.

Fuse #	Amp	Color	Circuit / Component Protected
1	50A	Red	ECM/PCM (Engine Control Module/Powertrain Control Module)
2	40A	Green	ABS (Anti-lock Braking System) Pump
3	30A	Green	Ignition Switch (Main Power)
4	25A	Clear	Fuel Pump (Main Power)
5	20A	Yellow	Headlight - Left Low Beam
6	20A	Yellow	Headlight - Right Low Beam
7	15A	Blue	Headlight - Left High Beam
8	15A	Blue	Headlight - Right High Beam
9	10A	Red	Horn
10	20A	Yellow	Blower Motor (Heater/AC)
11	10A	Red	A/C Clutch
12	30A	Green	Starter Relay Control
13	15A	Blue	ECM/PCM (Sensors/Actuators)
14	20A	Yellow	Transmission Control Unit (TCU)
15	5A	Tan	O2 Sensors
16	10A	Red	Cooling Fan Control (Low Speed)
17	15A	Blue	Cooling Fan Control (High Speed)
18	30A	Green	Trailer Brake Controller (Main Power)
19	20A	Yellow	Trailer Towing - Parking Lights
20	15A	Blue	Trailer Towing - Left Turn/Brake Light
21	15A	Blue	Trailer Towing - Right Turn/Brake Light
22	10A	Red	Wiper Motor - Low Speed
23	20A	Yellow	Wiper Motor - High Speed
24	10A	Red	Washer Pump

Relay Locations (Under-Hood):

The under-hood fuse box often houses several relays essential for various systems. Common relays found here include:

• Starter Relay: Controls the power to the starter motor.
• Fuel Pump Relay: Supplies power to the fuel pump.
• ECM/PCM Relay: Powers the main engine control unit.
• Cooling Fan Relays: Activates the engine cooling fan.
• Horn Relay: Powers the horn.
• AC Clutch Relay: Engages the air conditioning compressor clutch.

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Driver's Side Dash Fuse Box

This fuse box typically protects circuits for interior accessories, convenience features, and some lighting components within the cabin. This is usually located on the driver's side, behind a removable panel near the door or below the steering column.

Fuse #	Amp	Color	Circuit / Component Protected
1	15A	Blue	Radio/Infotainment System
2	10A	Red	Instrument Cluster
3	5A	Tan	OBD-II Port
4	20A	Yellow	Cigar Lighter/12V Outlet (Front)
5	15A	Blue	Power Windows - Driver's Side
6	15A	Blue	Power Windows - Passenger's Side
7	10A	Red	Interior Lighting
8	10A	Red	Power Mirrors
9	5A	Tan	Cruise Control
10	10A	Red	HVAC Control Panel
11	7.5A	Brown	Turn Signals/Hazard Lights
12	5A	Tan	Airbag System (SRS)
13	15A	Blue	Door Locks
14	20A	Yellow	Cabin Fuse Box (Input Power)
15	10A	Red	Brake Light Switch
16	10A	Red	Tail/Parking Lights (Left)
17	10A	Red	Tail/Parking Lights (Right)

Relay Locations (Driver's Side Dash):

Relays in this fuse box typically control cabin-specific functions or switch higher current loads for accessories. Common examples could include relays for power windows or the accessory power outlet.

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Passenger's Side Dash/Cargo Area Fuse Box (If Equipped)

Some Sprinter configurations, especially those with extensive upfitting or luxury packages, may have an additional fuse box on the passenger's side or in the cargo area to manage dedicated accessories or rear-specific electrical loads.

Fuse #	Amp	Color	Circuit / Component Protected
1	20A	Yellow	12V Outlet (Cargo Area)
2	15A	Blue	Auxiliary Heating/Cooling (Rear)
3	10A	Red	Rear Interior Lighting
4	25A	Clear	Power Sliding Door (If Equipped)
5	30A	Green	Inverter/Auxiliary Power (If Equipped)
6	15A	Blue	Additional Auxiliary Equipment

Relay Locations (Passenger's Side/Cargo Area):

Similar to other fuse boxes, dedicated relays may be present for high-current accessories in the cargo area, such as auxiliary power outlets or climate control systems.

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How to Test a Fuse

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

1. Safety First: Ensure the vehicle's ignition is off before working with fuses. If you're working under the hood, disconnect the negative battery terminal for added safety.
2. Locate the Fuse Box: Refer to the Quick Answer section to find the relevant fuse box.
3. Identify the Suspect Fuse: Use the fuse diagram (either in your owner's manual or on the fuse box lid) to locate the fuse for the circuit that is not working.
4. Visual Inspection: Most automotive fuses have a small wire visible through a clear housing. If this wire is broken or melted, the fuse is blown and needs replacement.
5. Use a Fuse Tester or Multimeter: For less obvious breaks, or for cartridge-style fuses, a fuse tester or multimeter is necessary.
   • Fuse Tester: These are simple tools that light up when a good fuse is inserted or when touched to the test points of an installed fuse, indicating continuity.
   • Multimeter: Set your multimeter to read continuity (often indicated by a beeping icon). Touch one probe to each metal terminal of the fuse. A good fuse will show continuity (a very low resistance reading or a beep). If there's no continuity, the fuse is blown.
6. Replace with Correct Amperage: If a 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, certain circuits are more prone to issues due to their usage or the components they protect. On a 2021 Mercedes-Benz Sprinter, common fuses that might blow include:

• Cigar Lighter/12V Outlets: These fuses often blow due to overloading with mobile chargers, air compressors, or other accessories drawing more power than the circuit is designed for. First, check what was plugged in.
• Headlights/Tail Lights: While less common with modern LED systems, a short in a wiring harness or a faulty bulb (if applicable) can still cause a fuse to blow. Visually inspect the light bulb and its connections.
• Blower Motor: A failing blower motor or an obstruction in the HVAC system that strains the motor can cause its fuse to blow. Listen for unusual noises from the blower or check if the fan is blocked.
• Radio/Infotainment System: Installation of aftermarket components or a short within the unit itself can sometimes lead to a blown fuse. Recall any recent work on the audio system.
• Trailer Brake Controller/Lighting: If you frequently tow, issues with the trailer's wiring or a short in the trailer's electrical system can transfer to the vehicle's fuse box. Check the trailer's wiring connections and lights.

Always remember to consult your owner's manual for the most accurate fuse box diagrams and specific information for your vehicle's trim level. Fuse locations and amperages can vary slightly based on installed options and regional configurations.

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