The alternator I bought from you doesn't work.

Each alternator is bench-tested before shipping. Apparent failure is usually due to ordering the wrong unit, shipping damage, or installation mistakes. Verify the part number, inspect for damage, and review the proper installation steps (Technical Tip TT-648) before contacting support.

The alternator I bought from you doesn't "put out".

Low-output symptoms are often caused by factors outside the alternator. Measure voltage directly at the rear of the unit with a digital meter; if readings seem low, check the common issues listed below or return the alternator for a free bench test.

High-output alternators ship with an overdrive pulley that may require a belt about 1 inch shorter than stock. Use a quality, oil-free belt to prevent slip and ensure full output.

Regulator plug not plugged in, not seated properly or pinched wire

Make sure the small regulator plug on the alternator is fully seated and oriented correctly. A pinched or missing connection will prevent charging. Self-exciting models (e.g., Fitzall 220A+) do not use this plug.

Battery warning light bulb in dash missing, blown or bad connection

Some vehicles rely on the dash battery-warning bulb to excite the alternator. A blown, missing, or poorly connected bulb can cause a no-charge condition.

Customer changed alternator pulley

Replacing the supplied overdrive pulley with a larger-diameter pulley slows the alternator and decreases charge output.

Vehicle crankshaft pulley diameter too small

Aftermarket under-drive crank pulleys spin accessories more slowly and can severely reduce alternator output. Ensure the crank pulley is at least OEM size.

Main vehicle charge wire too small or not upgraded

Factory charge wiring is sized for OE amperage. When loads rise, upgrade to a heavier-gauge cable such as the Big Zero kit to avoid voltage drop and false low-output symptoms.

Too many grounds, insufficient grounds, or just bad wiring

Improper, corroded, or excessive grounds-as well as undersized or poorly crimped wires-can cripple alternator performance. Have a qualified technician inspect and correct wiring.

Bad, old, weak, damaged or cheap battery

Weak or inexpensive batteries-especially some gel-cell types-may not accept the alternator's current. Use a healthy wet-cell battery with sufficient cold-cranking amps.

Alternator possibly damaged during installation

High-output units contain sensitive electronics. Skipping the recommended battery-disconnect procedure or other steps in Technical Tip TT-648 can damage the regulator and cause no-charge conditions.

The alternator I bought from you doesn't fit.

Direct-fit models require no hardware changes. Universal Fitzall 220A+ units need custom brackets and may require a shorter belt.

Do you sell brackets, spacers or hardware to mount the Fitzall on my particular application?

Due to the vast number of vehicles, PowerBastards does not supply custom mounting hardware. Most customers fabricate brackets themselves or hire a qualified shop.

I tested my alternator and it only makes 30A.

Alternators supply only the amperage the system demands. Clip-on amp meters can be inaccurate; 30 amps may be normal at low load. Send the unit in for a free certified output test if in doubt.

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High Output Alternators for GMC

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Your GMC isn't just a vehicle — it's your workhorse, weekend warrior, and everyday companion. When you depend on it to handle tough jobs or power-hungry accessories, a stock alternator just won't cut it. That's where our High Output Alternators for GMC come in. Designed for serious performance and durability, these alternators keep every system running strong.

Why Upgrade to a High-Output Alternator for GMC?

If you're adding big sound systems, off-road lights, winches, or heavy towing electronics, your factory alternator might struggle to keep up. A GMC high-amp alternator ensures your battery stays charged and all electronics get consistent power.

With a high amperage alternator for GMC, you can say goodbye to dim headlights, slow-moving power windows, and unexpected electrical failures. Our alternators deliver reliable output even at low RPMs, making them ideal for stop-and-go traffic or rugged terrain.

Engineered for Tough Jobs and Everyday Reliability

GMC vehicles like the Sierra, Yukon, Canyon, Acadia, and Terrain are built for demanding tasks. Our High Output Alternators for GMC match that same toughness.

Each GMC performance alternator is engineered using high-quality materials and advanced technology to withstand extreme conditions. Whether you're hauling heavy trailers or navigating rocky trails, your alternator needs to deliver steady power without fail.

Supported GMC Models

Sierra
— Perfect for supporting heavy towing, upgraded lighting, and additional work accessories.
Yukon
— Delivers reliable power for large SUVs loaded with advanced comfort and tech features.
Canyon
— Ideal for off-road builds and trucks equipped with winches, light bars, or other accessories.
Acadia
— Supports family-oriented tech systems, entertainment, and safety equipment without strain.
Terrain
— Provides steady power for smaller SUVs with modern electronics and added aftermarket gear.

Our aftermarket alternator GMC options are direct-fit replacements, making installation simple with no complicated modifications. Every unit undergoes strict quality control and performance testing to handle high electrical loads, maintain stable voltage even at idle, and perform consistently on tough terrain.

With a GMC alternator upgrade, you get dependable power, reduced risk of voltage drops, and long-lasting performance you can trust.

Benefits of a GMC High-Amp Alternator

Choosing a GMC high amp alternator from PowerBastards means more than just added power. Here's what you get:

Stable Voltage: No more flickering lights or slow electronics.
Improved Accessory Performance: Keep your winches, air compressors, and upgraded sound systems running at full strength.
Extended Battery Life: Reduce strain on your battery and avoid unexpected breakdowns.
Peace of Mind: Know that your GMC can handle all your electrical demands without hesitation.

A heavy-duty alternator GMC owners trust makes all the difference when you need extra juice for work or play.

Get the Right Alternator for Your GMC Model

Whether you drive a Sierra for tough towing, a Yukon for family adventures, or a Terrain for daily commutes, we have the perfect High Output Alternator for GMC to fit your needs. Check out our dedicated pages for each model to learn more and pick the best upgrade for your setup.