2019 Isuzu NQR — Fuse Box Diagram & Amperage

Quick answer

The 2019 Isuzu NQR (N‑Series cab‑over) typically has:

• Under‑dash fuse/junction box: Driver’s side lower dash/kick panel behind a snap‑off cover.
• Under‑hood/engine compartment fuse & relay box: On the left frame rail under the tilt cab, near the battery.
• Auxiliary/rear body or trailer fuse panel (if equipped by body builder): On rear frame rail or behind the passenger seat for PTO/trailer/body circuits. No trunk on this vehicle.

Always verify against the printed legend on the fuse box lid and your truck’s body‑builder options; allocations may vary by trim, transmission (Aisin auto vs. manual), ABS, PTO, and trailer wiring packages.

Under‑dash fuse/junction box (driver kick panel)

Typical layout shown below. Fuse numbering and exact positions can vary; confirm with the lid legend.

Relays in/near this box (varies by build):

• IG (Ignition) relay
• Blower relay
• Wiper relay
• Illumination/dimmer relay

Under‑hood fuse & relay box (left frame rail under tilt cab)

Holds main fusible links, power distribution, engine controls, and key relays. Diesel NQR allocations vary with emissions package; verify lid legend.

Key relays in this box:

• Starter relay
• A/C compressor (MG) relay
• Fuel pump/supply relay
• Headlamp relay (main)
• ECM/main relay
• Fan relay (if equipped)

Auxiliary / rear body or trailer fuse panel (if equipped)

Many NQR trucks are upfitted with an auxiliary panel for trailer lighting, trailer brake controller, PTO, and body functions. Location is typically on the rear frame rail, behind the cab, or behind the passenger seat. The following is a common upfitter configuration; your truck may differ.

Common relays mounted near this panel:

• Trailer tow/charge relay
• PTO enable relay
• Work light relay (body)

Note: Trailer brake controller grounds and charge circuits are frequent add‑ons; fuse sizing must match the controller/manufacturer spec.

How to test a fuse

• Visual check: Remove the suspect mini blade fuse and look for a melted/broken element. This is quick but not definitive.
• Test light method: With the circuit powered (key ON for most), probe both fuse test tabs. Both sides lit = good; one side lit = blown or no feed.
• Multimeter method: Check continuity (ohms) across the removed fuse, or check for 12V on both tabs with the fuse installed and circuit powered.
• If a fuse is blown, correct the cause before replacing. Never upsize a fuse; use the specified amperage. Inspect wiring/connectors for shorts to ground, especially near the tilt‑cab hinges, frame rail, and trailer connector.

Common blown fuses on this vehicle

• Cigar lighter/12V outlet (Fuse 1 under dash): Phone chargers and inverters commonly short. Check the socket for coins/debris and try a known‑good charger.
• Radio (Fuse 3 under dash): Aftermarket radio or telematics taps can overload. Verify proper ground and that memory/ACC leads aren’t tied together.
• Stop lamps (Fuse 5 under dash): If brake lights and ABS warning appear together, inspect the brake lamp sockets for corrosion and the trailer connector for water intrusion.
• Headlamps (Fuses 8/9 under dash and FL4 under hood): If one side is out, swap bulbs first; if both out, check the headlamp relay and FL4 main feed.
• Blower motor (Fuse 13 under dash): If the fuse pops on higher speeds, suspect a failing blower motor or shorted resistor/module.
• ECM/Injector (Under hood Fuses 1–4): No‑start or stall. Inspect harness near the left frame rail and at engine lifting brackets for rub‑through.
• Fuel pump/supply (Under hood Fuse 4): Long crank/no start. Listen for pump prime; check the pump relay and grounds at frame.
• ABS (Under hood FL3 and dash Fuse 16): ABS light on and pump inoperative—check the large ABS fusible link and wheel‑speed sensor wiring.
• Trailer circuits (Aux panel A1–A5): Blowing immediately points to a short in the 7‑way/plug or chafed trailer wiring near hinges/taillights.

Because Isuzu N‑Series trucks are frequently upfitted, fuse positions and even which box houses a given circuit can vary. Always confirm against the printed legend inside the lid and your body‑builder wiring diagrams before replacing fuses.

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