2015 GMC Sierra 2500HD Fuse Box Diagram & Amperage

Quick Answer

The 2015 GMC Sierra 2500HD has three main fuse box locations: under the hood (engine compartment), inside the cabin (instrument panel/driver's side kick panel), and in the rear (under the rear seat on the driver's side).

Under-Hood Fuse Box

The under-hood fuse block is located on the driver's side of the engine compartment, near the battery. This box contains fuses and relays for critical engine functions, lighting, and other high-current accessories.

Relay Locations (Under-Hood):

• R1 Battery Voltage Relay: Controls various high-current circuits.
• R2 Starter Relay: Engages the starter motor.
• R3 Fuel Pump Relay: Powers the fuel pump.
• R4 A/C Clutch Relay: Activates the A/C compressor clutch.
• R5 Run/Crank Relay: Powers various components when the engine is running or cranking.
• R6 High Beam Headlight Relay: Controls the high beam headlights.
• R7 Low Beam Headlight Relay: Controls the low beam headlights.

Note: Always refer to the fuse legend on the underside of your fuse box lid for the most accurate and trim-specific information, as fuse numbering and functions can vary slightly.

Instrument Panel Fuse Box (Cabin)

This fuse box is located on the driver's side of the dashboard, typically behind a removable panel on the side of the dash or under the steering column. It protects various interior electrical components.

*Note: The exact location of the cabin fuse box might require removing a trim panel. Consult your owner's manual for precise instructions.

Rear Under-Seat Fuse Box

Some 2015 GMC Sierra 2500HD models, particularly those with specific options or the crew cab configuration, may have an additional fuse box located under the rear seat on the driver's side. This fuse box typically handles circuits for rear accessories and power options.

*Note: Not all Sierra 2500HD trucks will have this fuse box. Check your owner's manual or inspect under the rear seat for confirmation.

How to Test a Fuse

Testing a fuse is a straightforward process. Here's how you can do it:

1. Safety First: Always turn off the ignition and remove the key before working with fuses. If testing an under-hood fuse box, disconnect the negative battery terminal for extra safety.
2. Locate the Fuse: Refer to your fuse box diagram (either on the fuse box lid or in your owner's manual) to find the suspected fuse.
3. Visual Inspection: Many fuses have a visible wire inside. If this wire is broken or melted, the fuse is blown. However, sometimes the damage isn't visible.
4. Use a Fuse Tester or Multimeter:
   • Fuse Tester: Insert the tester's probes into the two small test points on the top of the fuse. If the light on the tester illuminates, the fuse is good. If not, it's blown.
   • Multimeter: Set your multimeter to the continuity or ohm setting. Touch one probe to each metal blade of the fuse. A reading of near zero ohms (or a beep on continuity mode) indicates a good fuse. An "OL" (open loop) or no reading means the fuse is blown.
5. Replace (if necessary): If a fuse is blown, replace it with a new fuse of the exact same amperage (AMP) and type. Using a fuse with a higher amperage can cause serious electrical damage or fires.

Common Blown Fuses on This Vehicle

While any fuse can blow, some are more common than others. If you're experiencing an electrical issue, here are a few common culprits to check first on a 2015 GMC Sierra 2500HD:

• Cigar Lighter/Power Outlets (F3/F4 Instrument Panel): These fuses often blow due to overloads from charging multiple devices or using high-power accessories. Check the devices you're plugging in.
• Trailer Brake Control (F9 Under-Hood / F3 Rear Under-Seat): Issues with trailer wiring or a short in a trailer's electrical system can frequently blow these fuses. Inspect your trailer's wiring and connections.
• Blower Motor (F11 Under-Hood): A failing blower motor itself, a clogged cabin air filter, or an obstruction in the blower housing can cause the motor to draw too much current and blow its fuse.
• Headlights (F5-F8 Under-Hood): While less common, a short in the headlight wiring or a faulty bulb can occasionally cause these fuses to blow. Check the bulbs first.
• Radio/Infotainment (F1 Instrument Panel): Aftermarket installations or issues with the head unit itself can sometimes lead to this fuse blowing. If you've recently installed new audio equipment, double-check your wiring.

*Important: If a fuse blows repeatedly, there is an underlying electrical problem that needs to be diagnosed and repaired by a qualified technician. Simply replacing a fuse without addressing the root cause can lead to more significant damage.

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