2021 Isuzu NQR Fuse Box Diagram & Amperage

Quick Answer

Your 2021 Isuzu NQR has fuse boxes located in the following areas:

• Under-hood: Located on the driver's side, near the battery.
• Dash Kick-Panel: Behind a panel on the driver's side, near the kick panel.
• Relay Box (Additional): Often found near the main under-hood fuse box or tucked away in the engine bay, containing various relays.

Under-Hood Fuse Box (Main)

This fuse box contains fuses for critical engine and vehicle systems. Always verify the printed legend on the fuse box lid as configurations can vary slightly by trim and options.

Relay Locations (Under-Hood):

• R1 (Starter Relay): Engages the starter motor.
• R2 (Fuel Pump Relay): Powers the fuel pump.
• R3 (ECM Main Relay): Provides power to the Engine Control Module.
• R4 (Headlight Relay - Low Beam): Controls power to the low beam headlights.
• R5 (Headlight Relay - High Beam): Controls power to the high beam headlights.
• R6 (Blower Motor Relay): Powers the cabin blower motor.
• R7 (A/C Clutch Relay): Engages the air conditioning compressor clutch.

Dash Kick-Panel Fuse Box (Cabin)

This fuse box typically handles interior electrical components and accessories. Access it by removing the cover on the driver's side kick panel.

How to Test a Fuse

Testing a fuse is a straightforward process:

1. Safety First: Ensure the vehicle is off and the key is removed from the ignition. For under-hood fuses, disconnect the battery's negative terminal for extra safety, especially when working near high-amperage circuits.
2. Locate the Fuse Box: Refer to the "Quick Answer" section to find the correct fuse box.
3. Identify the Suspect Fuse: Consult the fuse box diagram (either from this guide or the legend on your fuse box lid) to find the fuse for the circuit you're troubleshooting.
4. Visually Inspect: Many fuses (especially mini and ATO blade fuses) have a clear plastic body. Look for a broken wire or blackened glass inside. If it's broken, the fuse is blown.
5. Use a Fuse Tester or Multimeter:
   • Fuse Tester: These are inexpensive tools with a light. Simply touch the probes to the test points on top of the fuse. If the light illuminates on both sides, the fuse is good. If it only lights on one side or not at all, the fuse is blown.
   • Multimeter (Continuity Setting): Set your multimeter to the continuity or Ohm setting. Remove the suspect fuse from its holder. Place one probe on each metal blade of the fuse. If you hear a beep or the multimeter reads a very low resistance (near 0 Ohms), the fuse is good. If there's no continuity (no beep or an "OL" reading for open loop), the fuse is blown.
6. Replace (if blown): Always replace a blown fuse with a new one of the exact same amperage rating and physical size. Using a fuse with a higher amperage can lead to serious electrical damage or fire. Using a lower amperage fuse will likely result in it blowing again immediately.

Common Blown Fuses on This Vehicle

While any fuse can blow, some circuits are prone to issues due to their load or common accessory usage. On the 2021 Isuzu NQR, you might frequently encounter issues with:

• Cigar Lighter / Power Outlet (F16 - Under-Hood, C10 - Dash): These fuses are often blown due to overcurrent from charging multiple devices or using high-power accessories. If your power outlets aren't working, check these first. Ensure no faulty chargers or accessories are plugged in.
• Blower Motor (F04 - Under-Hood, C06 - Dash): A failing blower motor or a blockage in the HVAC system can cause the blower motor fuse to blow. If your A/C or heat fan isn't working, this is a prime suspect. Check for obstructions in the blower fan.
• Headlights (F06, F07, F08, F09 - Under-Hood): While less common, a short in a headlight circuit or a faulty bulb can sometimes lead to a blown headlight fuse. If one or more headlights fail, check these fuses. Also, inspect the headlight bulbs themselves.
• Radio / Infotainment (C01 - Dash): Aftermarket radio installations or issues within the infotainment unit can sometimes pop this fuse. If your radio is dead, this is the first place to look. Consider if any recent modifications were made.
• Trailer Brake (F13 - Under-Hood): If you frequently tow and use the trailer brake system, this fuse can blow due to an issue with the trailer's wiring or an overloaded trailer brake controller. Always check the trailer's wiring for shorts if this fuse blows.

If you find a consistently blown fuse, it's crucial to investigate the underlying cause, as simply replacing the fuse without fixing the root problem will only lead to repeated fuse failures or potential damage to other components.

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