🔧 86 - 12V Battery Replacement

On your 86, the 12V battery sits in the engine bay and supplies power for starting and all electronics. Replacing it is straightforward, but the key is disconnecting and reconnecting the terminals in the correct order to avoid sparks or electrical damage.

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

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⚠️ Safety & Precautions

• ⚠️ Turn the car OFF, remove the key fob, and keep it away from the car during the job.
• ⚠️ Always disconnect the negative (-) terminal first and reconnect it last.
• ⚠️ Do not let a tool touch the battery positive (+) and any metal body part at the same time.
• ⚠️ Battery acid is corrosive—wear gloves and safety glasses.
• ⚠️ If the battery is leaking, cracked, or swollen, stop and replace carefully.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 3/8" ratchet
• 6" extension for ratchet
• 10mm combination wrench
• Small flathead screwdriver
• Battery terminal brush (specialty)
• Torque wrench (inch-pound)
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 12V battery (correct fitment for 86) - 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.
• Open the hood and let the engine bay cool if it’s hot.
• If you want to keep radio presets and learned settings, use a 12V memory saver (a device that keeps power to the car while the battery is disconnected). If you don’t have one, it’s okay—some settings may reset.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Locate the battery and remove covers

• Open the hood and locate the battery in the engine bay.
• If there is a small plastic cover or protective cap on the positive terminal, pop it open using a small flathead screwdriver.

Step 2: Disconnect the negative (-) cable first

• Use a 10mm socket with a ratchet to loosen the negative terminal clamp nut.
• Wiggle the clamp and lift it straight up off the battery post.
• Tuck the negative cable to the side so it cannot spring back and touch the battery.
• Negative first prevents accidental shorting.

Step 3: Disconnect the positive (+) cable

• Flip open the positive terminal cover (if equipped).
• Use a 10mm socket with a ratchet to loosen the positive terminal clamp nut.
• Lift the clamp straight up off the battery post and move it aside carefully.

Step 4: Remove the battery hold-down bracket

• Use a 10mm socket with a ratchet and extension to remove the hold-down nuts.
• Remove the hold-down bar/bracket and set it aside.

Step 5: Remove the old battery

• Wearing nitrile gloves, lift the battery straight up and out (it’s heavy—lift with your legs, not your back).
• Inspect the battery tray for corrosion or moisture.

Step 6: Clean the battery tray and terminals

• If you see powdery corrosion on the cable ends, clean the inside of each cable clamp using a battery terminal brush (specialty).
• If using anti-corrosion washers, install one on each battery post after the new battery is in place.

Step 7: Install the new battery and secure it

• Set the new battery into the tray in the same orientation as the old one.
• Reinstall the hold-down bracket and start the nuts by hand.
• Tighten using a 10mm socket and ratchet, then finish with a torque wrench (inch-pound): Torque to 7.5 N·m (66 in-lbs).

Step 8: Reconnect the positive (+) cable first

• Install the positive clamp onto the positive battery post.
• Tighten using a 10mm socket, then torque with a torque wrench (inch-pound): Torque to 5.4 N·m (48 in-lbs).
• Close the positive terminal cover.

Step 9: Reconnect the negative (-) cable last

• Install the negative clamp onto the negative battery post.
• Tighten using a 10mm socket, then torque with a torque wrench (inch-pound): Torque to 5.4 N·m (48 in-lbs).
• Spray a light coat of battery terminal protectant spray on both terminals (avoid soaking).

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✅ After Repair

• Start your 86 and confirm the engine cranks normally and runs smoothly.
• Check that headlights, hazards, and interior lights work.
• Reset the clock and re-save radio presets if they were lost.
• If the auto up/down window function acts weird, cycle each window fully down and fully up to help it relearn.
• Make sure the battery is firmly held down and cannot move.

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💰 DIY vs Shop Cost

Shop Cost: $180-$350 (parts + labor)

DIY Cost: $130-$260 (parts only)

You Save: $50-$150 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.