2018 Chevrolet Suburban — Fuse Box Diagram & Amp Ratings
Locations, fuse numbers, colors, circuits, and relay callouts
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Quick answer
The 2018 Chevrolet Suburban has three primary fuse/relay centers:
- Under-hood (engine compartment) fuse block: driver side of the engine bay, near the battery.
- Instrument panel (I/P) fuse block: driver-side dash end cap/kick-panel area, behind a pop-off cover.
- Rear compartment fuse block: left side of cargo area behind the trim panel (access panel near jack storage).
Note: GM used multiple fuse layouts on K2XX SUVs (LS/LT/Premier, 2WD/4WD, police/commercial). The tables below reflect the most common 2018 Suburban configuration. Always verify against the fuse legend printed on your fuse box lid and your owner’s manual for your exact VIN.
Engine compartment fuse block (under-hood)
Typical location: driver side, forward of the battery under a black plastic cover. Contains high-current J-case fuses, mini fuses, and several serviceable relays.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| F10 | 10A | Red | A/C compressor clutch |
| F31 | 15A | Blue | Left headlamp high beam |
| F33 | 15A | Blue | Right headlamp high beam |
| F34 | 15A | Blue | Left headlamp low beam |
| F35 | 15A | Blue | Right headlamp low beam |
| F42 | 15A | Blue | ECM/PCM power (ECM 1) |
| F43 | 20A | Yellow | Fuel pump (F/PMP) |
| F50 | 15A | Blue | ECM/PCM power (ECM 2 / TCM feed) |
| F55 | 15A | Blue | Heated oxygen sensors (HO2S) |
| F56 | 15A | Blue | Transmission control / ignition feed |
| F60 | 25A | Clear | ABS valve/solenoid power |
| F64 | 10A | Red | Trailer left stop/turn lamp |
| F65 | 10A | Red | Trailer right stop/turn lamp |
| F66 | 15A | Blue | Trailer parking/tail lamps |
| J6 | 40A | J-Case (varies) | Front blower motor power |
| J14 | 40–60A | J-Case (varies) | ABS pump motor |
| J16 | 30–40A | J-Case (varies) | Trailer battery charge feed |
| J17 | 30A | J-Case (varies) | Integrated trailer brake controller feed |
Relays in this block (common): Starter relay, A/C clutch relay, Engine control/Run relay, Fuel pump relay (some functions may be solid-state within the block). Relay names and positions are molded into the underside of the cover.
Instrument panel fuse block (driver dash end/kick-panel)
Typical location: remove the small trim cover at the driver-side end of the dash (visible with door open). Houses many body electronics fuses for interior features.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| F6 | 20A | Yellow | Cigar lighter / Front power outlet |
| F7 | 20A | Yellow | Console/aux power outlet |
| F8 | 20A | Yellow | Rear seat/cargo power outlet |
| F12 | 10A | Red | HVAC control module (panel) |
| F20 | 20A | Yellow | Radio/infotainment (main) |
| F21 | 10A | Red | Radio/infotainment display/telematics feed |
| F26 | 10A | Red | OnStar/communication module |
| F29 | 10A | Red | SIR/Airbag (module feed) |
| F31 | 10A | Red | IGN/Run/Crank sense to BCM |
| F35 | 10A | Red | Data link connector (OBD-II) / diagnostics |
| F40 | 15A | Blue | Stop lamps/CHMSL (brake light feed) |
Relays: Many “relays” for retained accessory power (RAP), ignition run/crank, etc., are solid-state within the Body Control Module (BCM) on this platform and are not separately serviceable at this location.
Rear compartment fuse block (cargo, left quarter trim)
Typical location: behind the left cargo trim panel; remove the access door near jack/tools to reach the block. Supports rear body, liftgate, audio, and rear HVAC circuits.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| F4 | 30A | Green | Rear HVAC blower motor |
| F5 | 30A | Green | Power liftgate module/motor (if equipped) |
| F11 | 20A | Yellow | Rear cargo 12V power outlet |
| F14 | 10–15A | Red/Blue | Tail/Park lamp feed (rear body) |
| F30 | 20–30A | Yellow/Green | Audio amplifier (Bose/amped systems) |
| F31 | 10A | Red | Rear vision camera (RVC) / display feed |
| F34 | 10A | Red | Rear park assist / parking sensors |
| F37 | 15A | Blue | Rear wiper/washer (if equipped) |
Relays: Rear defogger relay and liftgate relay are commonly integrated here or within the respective modules depending on trim. Exact relay positions are shown on the rear fuse block cover label.
How to test a fuse
- Visual check: Pull the suspect fuse with a fuse puller. If the metal element is melted or broken, replace it with the same amp rating and type.
- Test light method (in-car): With the key in Run, probe the two tiny test tabs on top of the fuse. Both sides should light. If only one side lights, the fuse is blown.
- Multimeter continuity: Remove the fuse and measure resistance across the blades. A good fuse will read near 0 ohms; OL/infinite means open.
- Load check: If a replacement blows immediately, stop and diagnose the circuit for shorts to ground, chafed wiring, or failed components before upsizing the fuse (never install a higher-amp fuse).
Tip: Note fuse color codes—Red 10A, Blue 15A, Yellow 20A, Clear 25A, Green 30A. High-current J-case fuse colors vary by manufacturer; always match the amp rating printed on the fuse.
Common blown fuses on this vehicle (what to check first)
- Power outlets/cigar lighter (F6/F7/F8 at I/P): Coins or metal debris in sockets; high-draw inverters and air pumps. Inspect the socket for damage before replacing the fuse.
- Trailer lighting (F64/F65/F66 under-hood): Shorted trailer wiring, corroded connectors, or incorrect trailer bulbs. Disconnect the trailer and retest—if the fuse holds, repair the trailer harness.
- Fuel pump (F43 under-hood): Rare to blow without cause. Check for a chafed harness at the tank/strap, water intrusion at the pump connector, or a failing pump drawing excessive current.
- Headlamps (F31/F33/F34/F35 under-hood): Moisture in lamp assemblies or aftermarket bulbs/ballasts can pop fuses. Verify correct bulb wattage and fix any water leaks.
- Radio/infotainment (F20/F21 at I/P): Aftermarket add-ons (USB hubs, amps) or pinched harnesses at the glove box/console. Pull aftermarket equipment to isolate.
- ABS (F60, J14 under-hood): If fuses blow, suspect a shorted ABS pump motor or chafed wheel-speed sensor harness near control arms.
- Rear HVAC blower (F4 rear block): Blower module failures can overcurrent. If the new fuse blows, test the rear blower resistor/module and motor.
If your Suburban’s fuse numbers differ from the above, use the legend printed on the fuse box lid—GM varies assignments by trim and options.
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Before you pull a fuse on the 2018 Chevrolet Suburban
- 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 Chevrolet Suburban
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 Chevrolet Suburban 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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