🔧 Sierra 1500 - Battery Replacement

On your Sierra 1500, there’s a normal 12V battery under the hood, and because your truck is Mild Hybrid (eAssist/MHEV), it may also have a high-voltage battery pack. The steps below cover the under-hood 12V battery (the one that starts and powers the truck’s 12V system).

Quick question (so I don’t steer you wrong): Are you replacing the 12V battery under the hood, or the hybrid/eAssist battery pack (high voltage)?

Difficulty Level: Beginner | Estimated Time: 0.5-1.0 hours

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⚠️ Safety & Precautions

• ⚠️ If you mean the hybrid/eAssist battery pack: don’t DIY—high voltage can cause severe injury; that job should be done by a trained technician.
• ⚠️ For the 12V battery: turn the truck fully OFF, keep keys away from the truck, and wait 2-3 minutes before disconnecting cables.
• ⚠️ Disconnect negative (-) first and reconnect it last to reduce the chance of a short.
• ⚠️ Batteries are heavy and contain acid; wear gloves and safety glasses.
• ⚠️ Do not allow your tool to touch the battery terminal and any metal body part at the same time.

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🔧 Required Tools

You'll need the following tools for this repair:

• 8mm socket
• 13mm socket
• 3/8" ratchet
• 6" socket extension
• Torque wrench (10-30 ft-lbs range)
• Battery terminal brush
• Trim tool
• Safety glasses
• Nitrile gloves
• Fender cover

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 12V AGM battery (Group 48/H6) - Qty: 1
• Battery terminal anti-corrosion washers - Qty: 2
• Battery terminal protectant spray - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Turn everything off (headlights, HVAC, radio) and remove the key/fob from the truck area.
• If you want to preserve radio presets: use a “memory saver” (a small device that keeps power while the battery is out). If you don’t have one, it’s okay—your truck will relearn settings.
• Open the hood and place a fender cover (a protective mat) over the fender edge to avoid scratches.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Locate the 12V battery

• Open the hood and find the battery on the passenger-side front of the engine bay.
• If a plastic cover is in the way, pop it off carefully using a trim tool.

Step 2: Disconnect the negative (-) cable first

• Use an 8mm socket with a 3/8" ratchet to loosen the negative (-) side-terminal bolt.
• Pull the negative cable straight out of the battery. Tuck it aside so it can’t spring back and touch the battery.
• If it’s tight, wiggle—don’t pry hard.

Step 3: Disconnect the positive (+) cable

• Use an 8mm socket with a 3/8" ratchet to loosen the positive (+) side-terminal bolt.
• Remove the positive cable and keep it from touching metal parts.

Step 4: Remove the battery hold-down

• At the base of the battery, remove the hold-down bolt using a 13mm socket, 6" extension, and 3/8" ratchet.
• Lift out the hold-down bracket and set it aside.

Step 5: Remove the old battery

• Grab the battery by the handle and lift it straight up and out.
• Lift with legs—batteries are heavy.

Step 6: Clean and prep the cables and tray

• Use a battery terminal brush to clean the inside of both cable ends (where they contact the battery terminals).
• If you’re installing them, place anti-corrosion washers onto the battery terminals.

Step 7: Install the new battery

• Set the new 12V AGM battery (Group 48/H6) into the tray in the same orientation as the old one.
• Reinstall the hold-down bracket and bolt using a 13mm socket, 6" extension, and 3/8" ratchet.
• Torque to 20 Nm (15 ft-lbs).

Step 8: Reconnect cables (positive first, negative last)

• Install the positive (+) cable first using an 8mm socket and 3/8" ratchet.
• Torque to 17 Nm (13 ft-lbs).
• Install the negative (-) cable last using an 8mm socket and 3/8" ratchet.
• Torque to 17 Nm (13 ft-lbs).

Step 9: Protect terminals and reinstall covers

• Spray both terminals lightly with battery terminal protectant spray.
• Reinstall any plastic battery/terminal covers by hand; use a trim tool only if needed.

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✅ After Repair

• Start the truck and confirm it cranks normally.
• Check for warning messages on the dash; some may clear after a short drive.
• Reset clock/radio presets if needed.
• If the power windows lose “one-touch/auto” function: hold the window switch all the way down for 5 seconds, then all the way up for 5 seconds.
• Do a quick charging check: with the engine running, electrical system voltage should typically be around 13.5-14.8V.

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💰 DIY vs Shop Cost

Shop Cost: $250-$450 (parts + labor)

DIY Cost: $180-$320 (parts only)

You Save: $70-$130 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.0 hours.

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🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.