2018 GMC Yukon Fuse Box Diagram & Amperage Guide

Quick Answer

The 2018 GMC Yukon (and Yukon XL) is equipped with three primary fuse box locations: under the hood (engine compartment), inside the cabin (driver's side instrument panel), and in the cargo area (rear of the vehicle).

2018 GMC Yukon Under-Hood Fuse Box

The under-hood fuse box is located on the driver's side of the engine compartment, near the battery. It houses fuses and relays for critical engine functions, lighting, and other high-current components. Always consult the diagram on the fuse box lid for the most accurate information for your specific trim level.

Common Under-Hood Relays:

• RL1: Fuel Pump Relay
• RL2: Starter Relay
• RL3: A/C Clutch Relay
• RL4: Headlight High Beam Relay
• RL5: Cooling Fan Relay

2018 GMC Yukon Instrument Panel Fuse Box (Cabin)

This fuse box is located on the driver's side, accessible by opening the driver's door and looking at the side of the dashboard, often behind a removable panel. This box primarily contains fuses for interior accessories, infotainment, and convenience features.

2018 GMC Yukon Rear Cargo Area Fuse Box

For the 2018 GMC Yukon, an additional fuse box is typically found in the rear cargo area, often on the driver's side, behind an access panel. This box usually contains fuses for rear-specific accessories, trailer wiring, and power outlets.

How to Test a Fuse

Testing a fuse is a straightforward process that can help diagnose electrical issues. You will need a multimeter or a fuse tester.

1. Safety First: Always turn off the ignition and any affected circuits before removing or testing fuses.
2. Locate the Fuse: Refer to the fuse box diagrams above and the label on your fuse box lid to find the suspected fuse.
3. Visual Inspection: Many modern fuses have a visible wire inside. If this wire is broken or melted, the fuse is blown. However, not all blown fuses are visually obvious.
4. Remove the Fuse: Use the plastic fuse puller usually found in the under-hood fuse box or needle-nose pliers to carefully remove the fuse.
5. Test with a Multimeter:
   • Set your multimeter to the continuity setting (often indicated by a speaker or diode symbol).
   • Touch one probe to each metal blade of the fuse.
   • A good fuse will show a reading of zero ohms or beep, indicating continuity. A blown fuse will show an "OL" (open circuit) or no reading, and no beep.
6. Test with a Fuse Tester: Insert the fuse into the tester. If the light on the tester illuminates, the fuse is good. If it doesn't light up, the fuse is blown.
7. Replace the Fuse: If the fuse is blown, replace it with a new fuse of the exact same amperage rating and type. Using a fuse with a higher rating can lead to serious electrical damage or fire.

Common Blown Fuses on This Vehicle

While any fuse can blow, some are more common culprits for specific issues on a 2018 GMC Yukon:

• Cigar Lighter / 12V Outlets (Fuse F8 in Instrument Panel Fuse Box): Often blows due to overcurrent from charging multiple devices or using high-power accessories. Check first: Disconnect all devices and try a new fuse.
• Blower Motor (Fuse F11 in Under-Hood Fuse Box): Can blow if the blower motor is working too hard due to a clogged cabin air filter or a failing motor. Check first: Replace cabin air filter, ensure no obstructions in the blower motor area.
• Radio / Infotainment System (Fuse F1 in Instrument Panel Fuse Box): Less common, but can blow due to an internal fault in the radio or a short in the wiring. Check first: Ensure no recent aftermarket installations or wiring modifications.
• Trailer Brake Controller (Fuse F16 in Under-Hood Fuse Box for some models, or rear fuse box): Frequently blows due to issues with trailer wiring, a short in the trailer brake system, or an overloaded circuit. Check first: Inspect trailer wiring for damage or shorts.
• Headlights (Fuses F5-F8 in Under-Hood Fuse Box): While bulbs are more common to fail, a fuse can blow due to a short in the headlight assembly or wiring. Check first: Inspect the physical headlight bulb, then wiring for any visible damage.

Always remember that a blown fuse is often a symptom of an underlying problem. If a fuse blows repeatedly, consult a qualified technician to diagnose the root cause.

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