🔧 TLX - 12V Battery Replacement

Replacing the 12V battery restores reliable starting and protects sensitive electronics from low-voltage issues. On your TLX, the battery sits in the engine bay and is held down by a simple bracket and two cables.

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

Assumption: Stock 12V battery and factory hold-down hardware.

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⚠️ Safety & Precautions

• ⚠️ Turn ignition OFF and keep the key fob at least 10 feet away.
• ⚠️ Wear eye protection and gloves; batteries can vent corrosive acid.
• ⚠️ Never let a tool touch both battery terminals at once.
• ⚠️ Disconnect negative (-) first and reconnect it last to prevent accidental shorting.
• ⚠️ If the battery is cracked, swollen, or leaking, do not handle it—replace safely.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 1/4" ratchet
• 6" extension for 1/4" ratchet
• 10mm combination wrench
• Torque wrench (5–25 Nm range)
• Battery terminal brush
• Memory saver (OBD-II) (specialty)
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 12V battery (correct group size for TLX) - Qty: 1
• Battery terminal corrosion protection pads - Qty: 2
• Battery terminal protectant spray - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to P, and set the parking brake.
• Open the hood and make sure all lights/accessories are OFF.
• If you want to keep radio presets and some memory settings, connect a memory saver (OBD-II) (a small device that supplies low power through the diagnostic port) before disconnecting the battery.
• Plan your order: negative (-) off first, then positive (+).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Access the battery

• Open the hood and locate the 12V battery at the front of the engine bay.
• If there’s a plastic cover or air duct blocking access, remove its clips/fasteners using a 10mm socket and 1/4" ratchet (some cars may not have one).

Step 2: Disconnect the negative (-) terminal

• Use a 10mm socket with a 1/4" ratchet to loosen the nut on the negative (-) terminal clamp (usually black).
• Twist and lift the clamp off the battery post, then tuck it to the side so it can’t spring back.
• Tip: Wiggle—don’t pry hard.
• Torque on install: 5 Nm (44 in-lbs)

Step 3: Disconnect the positive (+) terminal

• Flip open the red protective cover (if equipped).
• Use a 10mm socket and 1/4" ratchet to loosen the positive (+) terminal clamp nut.
• Lift the clamp straight up and move it aside without letting it touch metal parts.
• Torque on install: 5 Nm (44 in-lbs)

Step 4: Remove the battery hold-down

• The battery is secured by a bracket/rod style hold-down.
• Use a 10mm socket, 6" extension, and 1/4" ratchet to remove the hold-down nuts/bolts.
• Lift the hold-down bracket off and set it aside.
• Torque on install: 9.8 Nm (7 ft-lbs)

Step 5: Remove the old battery

• Grab the battery by its handle (if it has one) and lift it straight up and out.
• Batteries are heavy; keep your back straight and lift with your legs.

Step 6: Clean the tray and terminals

• Check the battery tray for corrosion (white/green crust).
• Use a battery terminal brush to clean the inside of both cable clamps until the metal looks bright.
• Install corrosion protection pads on the posts (optional but recommended).

Step 7: Install the new battery

• Set the new battery into the tray in the same orientation as the old one (posts in the same positions).
• Reinstall the hold-down bracket using a 10mm socket, extension, and 1/4" ratchet.
• Tighten with a torque wrench: Torque to 9.8 Nm (7 ft-lbs).
• Tip: Battery should not move by hand.

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

• Install the positive (+) clamp first. Use a 10mm socket to snug it, then use a torque wrench: Torque to 5 Nm (44 in-lbs).
• Close the red protective cover (if equipped).
• Install the negative (-) clamp last. Use a 10mm socket, then torque: Torque to 5 Nm (44 in-lbs).
• Spray a light coat of battery terminal protectant on the terminals (optional).

Step 9: Reinstall any covers you removed

• Reinstall ducts/covers using the 10mm socket and 1/4" ratchet.
• Make sure no tools are left in the engine bay.

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✅ After Repair

• Start the engine and confirm the battery light turns off normally.
• Set the clock and re-save radio presets if they were lost.
• Power window reset (if needed): with engine running, fully lower each window, then fully raise and hold the switch up for 2 seconds.
• Let the engine idle for 5–10 minutes with accessories off; the computer may “relearn” idle after battery power loss.
• Check that the battery is secure and the terminals don’t twist by hand.

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💰 DIY vs Shop Cost

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

DIY Cost: $160-$280 (parts only)

You Save: $90-$170 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.