2018 Isuzu NPR Fuse Box Diagram & Amperage
Detailed diagrams and amperage ratings for all fuse boxes on your 2018 Isuzu NPR, including ECM, fuel pump, lights, and accessories.
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Quick Answer
The 2018 Isuzu NPR typically features three main fuse box locations: under the hood (engine compartment), inside the cabin (driver's side kick panel), and sometimes a smaller auxiliary box, though the primary ones are under the hood and in the cabin. Always consult your vehicle's owner's manual for the most accurate and specific information.
Under-Hood Fuse Box
The under-hood fuse box contains fuses and relays for critical engine functions, high-current components, and some chassis systems. It's usually located on the driver's side of the engine compartment, near the battery. Open the lid to reveal the fuse layout and often a printed legend.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| F1 | 10A | Red | ECM/PCM (Engine Control Module/Powertrain Control Module) |
| F2 | 15A | Blue | Fuel Pump |
| F3 | 20A | Yellow | Ignition System |
| F4 | 30A | Green | Starter Relay |
| F5 | 15A | Blue | Headlights Low Beam (Left) |
| F6 | 15A | Blue | Headlights Low Beam (Right) |
| F7 | 10A | Red | Headlights High Beam (Left) |
| F8 | 10A | Red | Headlights High Beam (Right) |
| F9 | 20A | Yellow | ABS (Anti-lock Braking System) |
| F10 | 25A | Clear | A/C Clutch |
| F11 | 30A | Green | Blower Motor (High Speed) |
| F12 | 10A | Red | Daytime Running Lights (DRL) |
| F13 | 10A | Red | Horn |
| F14 | 20A | Yellow | Trailer Brake Control (if equipped) |
| F15 | 10A | Red | Transmission Control Module (TCM) |
| F16 | 15A | Blue | Cooling Fan Relay |
Relays in Under-Hood Fuse Box:
- Starter Relay: Engages the starter motor.
- Fuel Pump Relay: Powers the fuel pump.
- Main Relay: Powers various engine control circuits.
- Headlight Relays (Low/High Beam): Control headlight operation.
- Cooling Fan Relay: Activates the engine cooling fan.
- A/C Clutch Relay: Engages the A/C compressor clutch.
Cabin Fuse Box (Driver's Side Kick Panel)
The cabin fuse box, often located behind a removable panel on the driver's side kick panel or dashboard, houses fuses for accessories, interior lighting, and various electronic systems. Consult the printed diagram on the back of the panel or in your owner's manual for the exact layout.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| F1 | 10A | Red | Radio/Infotainment System |
| F2 | 15A | Blue | Cigar Lighter/12V Power Outlet 1 |
| F3 | 15A | Blue | Cigar Lighter/12V Power Outlet 2 |
| F4 | 20A | Yellow | Blower Motor (Lower Speeds) |
| F5 | 10A | Red | Parking Lights / Tail Lights |
| F6 | 10A | Red | Brake Lights |
| F7 | 10A | Red | Turn Signals / Hazard Lights |
| F8 | 15A | Blue | Power Windows |
| F9 | 10A | Red | Interior Cabin Lights |
| F10 | 10A | Red | Instrument Cluster |
| F11 | 10A | Red | ABS Warning Light |
| F12 | 15A | Blue | Wiper Motor |
| F13 | 10A | Red | Airbag System (Supplemental Restraint System - SRS) |
| F14 | 10A | Red | HVAC Control (Heater, Ventilation, A/C) |
| F15 | 7.5A | Brown | OBD-II Port |
| F16 | 20A | Yellow | Power Door Locks |
Relays in Cabin Fuse Box:
- Accessory Relay: Powers various interior accessories when the ignition is on.
- Blower Motor Relay: Controls power to the blower motor.
- Turn Signal Flasher Relay: For turn signals and hazard lights.
How to Test a Fuse
Testing a fuse is a straightforward process that can help you quickly identify if a circuit problem is due to a blown fuse. You'll need a fuse puller (usually found in the fuse box lid or with the vehicle's tools) and a multimeter or a fuse tester.
- Locate the Fuse: Identify the suspect fuse using the fuse box diagram on the lid or in your owner's manual.
- Turn Off the Ignition: Always turn off the vehicle's ignition and any accessories before working with fuses to prevent accidental short circuits or electrical damage.
- Remove the Fuse: Use the fuse puller to carefully remove the fuse. Never use pliers or other metal tools that could damage the fuse or the fuse box.
- Visual Inspection: Hold the fuse up to a light. If the metal wire or strip inside the fuse is broken or appears burnt, the fuse is blown and needs replacement.
- Test with a Multimeter (Continuity Test):
- Set your multimeter to the
Before you pull a fuse on the 2018 Isuzu NPR
- 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 2018 Isuzu NPR
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
2018 Isuzu NPR 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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