Every fall, our service team hears the same questions from GMC owners around Wilmington and the surrounding Will and Grundy County area. We've collected the most common ones here, so you can head into winter knowing your truck or SUV will start when you need it.
Frequently Asked Questions
How long should my GMC battery last?
A standard 12-volt vehicle battery typically lasts 3 to 5 years. Northern Illinois weather is especially tough on batteries: severe summer heat wears them down internally by corroding grid plates and evaporating electrolyte fluid, and winter cold exposes that hidden weakness. If yours is approaching the three-year mark, a digital battery conductance test this fall is a smart move. Battery testing is available any time at our service center.
It started fine yesterday. Why won't it start today?
Cold weather drastically drops a battery's power output while simultaneously increasing the power your engine needs to turn over. At 32°F, a 12-volt battery loses roughly 20% of its available Cold Cranking Amps (CCA), and at 0°F, output drops by nearly 50%. At the same time, cold engine oil thickens, requiring significantly more energy to crank over. A battery that barely got by at 50 degrees may have nothing left at 10 degrees.
What are the early warning signs?
Common indicators that your GMC battery or electrical system requires attention include:
Slow, groaning starts: The engine cranks sluggishly, especially first thing in the morning.
Dashboard alert messages: A battery symbol or charging-system message illuminates on the dash.
Electrical glitches: Interior lights dim, or the touchscreen display flickers or reboots during startup.
Disabled Auto Stop/Start: The vehicle automatically disables the Auto Stop/Start system to preserve battery charge.
Frequent jump starts: Needing a jump start, even once, indicates the battery can no longer maintain a full 12.6-volt resting charge.
I tow and haul. Does that matter?
Yes, heavy utility loads put extra demand on your vehicle’s electrical system. A Sierra or Canyon pulling a trailer, or running accessories like an electric winch, plow, auxiliary LED light bar, or trailer brake controller, places a much higher load on the battery and alternator. Heavy-duty use calls for a high-CCA battery in top condition and an alternator charging properly between 13.8 and 14.7 volts. We test both.
Can I just buy any battery that fits?
No, we don't recommend it—many newer GMC models require a specific AGM battery. GMC trucks and SUVs equipped with Auto Stop/Start are designed for an Absorbent Glass Mat (AGM) battery, which handles rapid charge-discharge cycling. A standard flooded lead-acid battery that physically fits but isn't the right type or capacity can trigger warning messages, disable features, and wear out early. We install the factory-specified battery for your vehicle.
What about my Hummer EV or Sierra EV?
Yes, GMC's electric trucks and SUVs still use a traditional 12-volt auxiliary battery to wake up the vehicle and run accessories. The 12-volt battery powers low-voltage systems, control modules, keyless entry, and the high-voltage contactors that engage the main propulsion battery. A weak 12-volt can keep an EV from powering on or driving, so it should be checked before winter too.
How long does a battery test take?
A professional battery test usually takes just a few minutes. We check the battery's remaining Cold Cranking Amps (CCA) and state of charge, test the alternator and charging system under load, inspect cables and terminals for corrosion, and show you the direct results.
Get Winter-Ready at Arnie Bauer GMC
Bring your GMC to Arnie Bauer GMC at 901 E. Baltimore St., Wilmington, IL 60481. We're proud to serve neighbors from Wilmington, Joliet, Braidwood, Coal City, Diamond, and Channahon.
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Service Hours: Monday–Friday 8:00 AM–4:30 PM | Saturday 8:00 AM–1:00 PM