2021 Ram 3500 Fuse Box Diagram & Amperage
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Quick Answer
The 2021 Ram 3500 has two primary fuse box locations:
- Under-Hood Power Distribution Center: Located in the engine bay on the driver's side.
- Interior Fuse Panel: Located on the driver's side, under the dashboard to the left of the steering column.
Always consult the diagram printed on the inside of the fuse box cover to confirm fuse numbers and locations, as they can vary based on your truck's specific trim level and options.
Under-Hood Power Distribution Center
This is the main fuse box and contains high-amperage fuses and relays for critical vehicle systems. To access it, open the hood and look for a black plastic box on the driver's side near the fender.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| F03 | 30A | Pink | Trailer Tow |
| F05 | 40A | Green | Anti-lock Brake System (ABS) Pump |
| F06 | 30A | Pink | Anti-lock Brake System (ABS) Valves |
| F10 | 40A | Green | Blower Motor (Front) |
| F14 | 20A | Yellow | Fuel Pump Motor |
| F20 | 20A | Yellow | Starter Solenoid |
| F21 | 25A | Natural | A/C Clutch |
| F28 | 20A | Yellow | Left Low-Beam Headlamp |
| F29 | 20A | Yellow | Right Low-Beam Headlamp |
| F30 | 15A | Blue | Left High-Beam Headlamp |
| F31 | 15A | Blue | Right High-Beam Headlamp |
| F34 | 25A | Natural | Powertrain Control Module (PCM) / Engine Control Module (ECM) |
| F42 | 20A | Yellow | Cigarette Lighter / 12V Power Outlet |
| F43 | 20A | Yellow | Horn |
| F47 | 30A | Green | Trailer Brake Controller |
| F60 | 30A | Pink | Airbag Module (OCM/SDM) |
| F71 | 25A | Natural | Ignition Coils / Powertrain |
Relay Locations (Under-Hood)
- Starter Relay: Integrated into the fuse box assembly.
- Fuel Pump Relay: Integrated into the fuse box assembly.
- A/C Clutch Relay: Integrated into the fuse box assembly.
- Blower Motor Relay: Integrated into the fuse box assembly.
Interior Fuse Panel (Driver's Side Kick Panel)
This fuse panel handles circuits for interior electronics and accessories. It's located under the dashboard, typically behind a small access door near the driver's left foot.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| F90 | 10A | Red | Parking Lamps / Tail Lamps |
| F91 | 10A | Red | Stop Lamps / Brake Light Switch |
| F94 | 20A | Yellow | Radio / Infotainment System |
| F95 | 10A | Red | Airbag System |
| F97 | 15A | Blue | Instrument Panel Cluster (Gauges) |
| F98 | 20A | Yellow | 12V Power Outlet (Console) |
| F100 | 10A | Red | Cabin Fuse / Body Control Module |
How to Test a Fuse
Testing a fuse is a simple process. You can often tell if a fuse is blown just by looking at it.
- Turn off the ignition and the component that isn't working.
- Locate the correct fuse box.
- Remove the fuse. Most fuse boxes have a small plastic fuse puller tool clipped inside. If not, needle-nose pliers work carefully.
- Inspect the metal strip. Look at the thin metal strip inside the plastic body of the fuse. If the strip is broken or looks melted, the fuse is blown and needs to be replaced.
- Use a multimeter (for a more definitive test). Set your multimeter to the continuity setting (it usually has a sound icon). Touch one probe to each metal blade on top of the fuse. If the multimeter beeps, the fuse is good. If it remains silent, the fuse is blown.
- Replace the fuse. If the fuse is blown, replace it with a new fuse of the exact same amperage rating. Using a higher-rated fuse can cause a fire.
Common Blown Fuses on the 2021 Ram 3500
- Cigarette Lighter / 12V Power Outlet (F42, F98): This is one of the most common fuses to blow. It often happens when a faulty phone charger or other plug-in device shorts out the circuit. Before replacing the fuse, unplug everything from the power outlets.
- Trailer Tow Fuses (F03, F47): If your trailer lights or trailer brakes aren't working, these fuses are the first place to check. The issue is often caused by faulty or corroded wiring on the trailer itself. Inspect the trailer's wiring harness and connector for damage or moisture before replacing the fuse.
- Fuel Pump Fuse (F14): If your truck cranks but won't start, a blown fuel pump fuse could be the culprit. This can sometimes be a sign of a failing fuel pump that is drawing too much current. If the new fuse blows again, it's time for a professional diagnosis.
If a fuse blows immediately after you replace it, you have a short circuit in that component's wiring that needs to be diagnosed and repaired.
Find a trusted shop on Repairius.
Before you pull a fuse on the 2021 Ram 3500
- Use the label printed on the panel cover or the owner's manual for your exact build. Layouts change with options, model year and build date, so a chart for another truck can be wrong.
- Replace a blown fuse only with the same amp rating. A larger fuse can let wiring overheat.
- A fuse that blows again right away means a short or failing component downstream. Find the cause before replacing it again.
- A good fuse doesn't prove the circuit works — relays, grounds and connectors fail too.
- Disconnect the battery before working near high-current fuses or cables.
Learn more: How fuses, relays and truck electrical systems work
More specs for the 2021 Ram 3500
Oil Capacity & Filter
Capacity, weight, filter PN, drain plug torque, change interval.
Fluid Type Specs
Engine oil, coolant, ATF, diff, brake, PS, DEF — with OEM spec numbers.
Coolant Capacity & Type
Total system capacity, OEM coolant spec, flush interval, bleed tips.
Transmission Fluid & Service
Trans model, fluid spec, capacity, filter PN, service interval.
Torque Specifications
Lug nuts, drain plug, caliper, axle nut, plug, key fasteners.
Brake Pad & Rotor Specs
Pad PNs, rotor size, min thickness, caliper torque.
Tire Size & Pressure
OEM size, cold psi, bolt pattern, wheel size, TPMS.
Battery Size & Group
Group size, CCA, AGM/flooded, dimensions, reset note.
A/C Refrigerant & Oil
R-134a or R-1234yf, charge oz, PAG oil spec.
Bulb Sizes (Headlight, Tail, Fog)
Headlight, fog, tail, turn, reverse, interior.
Factory Maintenance Schedule
Service intervals by mileage, severe-duty notes, known issues.
Towing Capacity & Payload
Max tow, payload, GVWR/GCWR, hitch class by trim.
Serpentine Belt Routing & Length
Belt routing, length, rib count, OEM + aftermarket PNs.
Wheel Alignment Specifications
Camber, caster, toe ranges (front & rear), adjustability notes.
Paint Color Codes
All factory colors with paint codes, sticker location, touch-up tips.
Wiper Blade Sizes
Driver/passenger/rear blade size, attachment, OEM + cross-refs.
Spark Plug Type & Gap
Plug PN, gap, torque, interval by engine.
Transmission & Axle Gear Ratios
Trans gear ratios, axle ratios, RPO codes, tow vs MPG impact.
Key Fob Programming
DIY programming steps, FCC ID, fob PN, battery, transponder.
Same spec — other model years
Maintenance & repair guides
2021 Ram 3500 Maintenance Schedule →
Available maintenance guidance; confirm the manufacturer schedule.
Repair planning references →
Plan the scope of work; detailed procedures need configuration-matched evidence.
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Values can vary by engine, trim and build date; check your VIN-specific service information. Updated 2026-08-19.