2018 Toyota Tundra Fuse Box Diagram & Amperage Guide
Locate your 2018 Toyota Tundra fuses, learn their amp ratings, and find out how to test them.
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As an ASE-certified master technician, I’ve spent countless hours tracking down electrical gremlins. Often, the culprit behind a dead radio, faulty fuel pump, or inoperable trailer brake is a simple blown fuse. If you're working on a 2018 Toyota Tundra, having a handy reference guide for your fuse boxes can save you a lot of time and money.
Note: Trim levels, bed configurations, and tow packages can alter the exact fuse layout. The diagrams below represent the most common configuration for the 2018 Toyota Tundra. Always verify the printed legend on the inside of your fuse box lid before replacing any fuse!
Quick Answer: 2018 Toyota Tundra Fuse Box Locations
The 2018 Toyota Tundra features two primary fuse box locations:
- Engine Compartment Fuse Box: Located under the hood on the driver's side, just behind the battery. This box houses high-amperage fuses, critical engine management components, and towing circuits.
- Passenger Compartment Fuse Box: Located inside the cabin, under the driver's side dash (kick panel area). This box protects interior accessories, lighting, and convenience features.
Engine Compartment Fuse Box
To access the under-hood fuse box, open the hood and locate the black rectangular box behind the battery. Press the tabs on the side of the cover to lift it off. The inside of the lid has a diagram, but here are the most important circuits you need to know.
| Fuse / Relay Name | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| EFI NO. 1 | 25A | Clear/White | Electronic Fuel Injection (EFI), Engine Control Module (ECM) |
| EFI NO. 2 | 10A | Red | Fuel Pump, Purge Valve, Emissions |
| H-LP LH | 15A | Blue | Left-hand Headlight (Low/High Beam) |
| H-LP RH | 15A | Blue | Right-hand Headlight (Low/High Beam) |
| TOWING | 30A | Green | Trailer Brake Controller, Towing Package |
| TOW TAIL | 30A | Green | Trailer Tail Lights |
| ABS NO. 1 | 50A | Red (Cartridge) | Anti-lock Braking System (ABS) module |
| ABS NO. 2 | 30A | Pink (Cartridge) | Anti-lock Braking System (ABS) motor |
| A/C COMP | 10A | Red | Air Conditioning Compressor Clutch |
| RADIO NO. 1 | 20A | Yellow | Audio System, Infotainment Head Unit |
| STARTER | 30A | Green | Starter Relay / Solenoid |
| HORN | 10A | Red | Dual Horns |
| ALT | 140A/150A | - | Alternator (Main Fusible Link) |
Relay Locations: This box also houses vital relays, including the EFI Relay, Fuel Pump Relay, Starter Relay, A/C MG/C Relay (compressor clutch), and Towing Relays.
Passenger Compartment (Dash) Fuse Box
The interior fuse box is located under the driver’s side dashboard. You may need to remove a small plastic cover panel near your left knee/foot (the kick panel) to access the fuses.
| Fuse # / Name | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| P/OUTLET | 15A | Blue | 12V Power Outlet (Center Console/Dash) |
| CIG | 15A | Blue | Cigarette Lighter / Front 12V Outlet |
| ACC | 7.5A | Brown | Accessory System, Power Mirrors, Clock |
| IGN | 7.5A | Brown | Ignition System, Multi-port Fuel Injection |
| SRS | 10A | Red | Supplemental Restraint System (Airbags) |
| TAIL | 15A | Blue | Tail Lights, Parking Lights, License Plate Lights |
| STOP | 15A | Blue | Brake Lights, High-Mount Stop Light |
| WIPER | 30A | Green | Windshield Wipers and Washers |
| HTR | 50A | Red (Cartridge) | Blower Motor (Heater/AC Fan) |
| OBD | 7.5A | Brown | On-Board Diagnostics (OBD-II Data Link Connector) |
| RADIO NO. 2 | 7.5A | Brown | Audio System (Ignition switch routed) |
| BK/UP | 10A | Red | Backup Lights, Reverse Camera |
How to Test a Fuse
Before you start ripping apart wiring harnesses, make sure you know how to properly test a fuse. Visual inspections (looking for a broken metal wire inside the plastic casing) are okay, but testing is much more reliable.
- Use a Digital Multimeter: Set your multimeter to the continuity setting (the one that beeps). Touch one probe to each of the exposed metal tabs on top of the fuse while it's still plugged into the fuse box (ensure the key is in the ON position if the circuit is switched). If the meter beeps, the fuse is good. No beep means it's blown.
- Use a Test Light: Ground the clamp of your 12V test light to a solid, bare metal chassis point. Touch the probe to one of the test points on the top of the fuse, then touch the other point. If it lights up on both sides, the fuse has continuity and is good. If it only lights up on one side, the fuse is blown.
- Always replace with the exact amperage: Never put a 30-amp fuse in a 15-amp slot. You risk melting the wiring harness or starting a fire!
Common Blown Fuses on the 2018 Tundra
Over my years in the shop, I've noticed a few fuses on the Tundra that blow more often than others:
- TOWING / Trailer Fuses (30A): The Tundra is a workhorse, but a bad ground or a short on a rented utility trailer will instantly pop the Tundra's tow fuses. Always inspect the trailer plug and wiring before replacing the fuse.
- P/OUTLET and CIG Fuses (15A): Often blown by faulty phone chargers, portable air compressors, or loose coins falling into the 12V socket. If your phone won't charge, check this fuse in the kick panel first.
- RADIO NO. 1 (20A): Aftermarket audio installations or jump-starting the battery backward (even for a split second) will almost always pop the primary radio fuse in the engine compartment.
Electrical issues can be frustrating, but taking the time to test your fuses is step number one.
Find a trusted shop on Repairius.
Before you pull a fuse on the 2018 Toyota Tundra
- 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 Toyota Tundra
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 Toyota Tundra 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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