🔧 BRZ - Alternator Replacement

The alternator charges your battery and powers the electrical system while the engine is running. On your BRZ, it’s belt-driven at the front of the engine, so you’ll remove the accessory drive belt, unplug the wiring, and swap the unit.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.0 hours

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⚠️ Safety & Precautions

• ⚠️ Disconnect the battery first: the alternator main cable is always “hot” and can short if it touches metal.
• ⚠️ Work on a cold engine to avoid burns near the radiator/fans.
• ⚠️ If you raise the car, support it with jack stands before going underneath.
• ⚠️ Keep fingers and tools clear of the belt path and pulleys.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Mechanic gloves
• Wheel chocks
• Floor jack (rated 2-ton minimum)
• Jack stands (rated 2-ton minimum)
• 10mm socket
• 10mm wrench
• 12mm socket
• 14mm socket
• 14mm combination wrench
• 3/8" ratchet
• 3/8" torque wrench
• 6" socket extension
• Flat trim tool
• Flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Alternator - Qty: 1
• Accessory drive belt (serpentine belt) - Qty: 1

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📋 Before You Begin

• Park on level ground, put the shifter in neutral, and set the parking brake.
• Open the hood and let the engine cool fully.
• Disconnect the battery: use a 10mm wrench to remove the negative (−) terminal and tuck it aside so it can’t spring back.
• Take a quick photo of the belt routing.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the intake ducting for access

• Use a flat trim tool to release any plastic clips on the front intake snorkel/duct.
• Use a 10mm socket and 3/8" ratchet to remove the air duct/airbox fasteners as needed, then lift the ducting out of the way.

Step 2: (Optional but helpful) Raise the front for easier belt access

• Place wheel chocks behind the rear wheels.
• Lift the front with a floor jack and support with jack stands at the proper front support points.
• Use a flashlight to see the belt and tensioner clearly.

Step 3: Release belt tension and remove the accessory belt

• The “serpentine belt” is the single belt that drives the alternator and other accessories.
• From the front of the engine, put a 14mm combination wrench on the belt tensioner hex.
• Rotate the tensioner to relieve tension, then slip the belt off the alternator pulley.
• Slowly release the tensioner back to its resting position.

Step 4: Disconnect the alternator electrical connections

• Unplug the alternator connector by pressing the tab and pulling straight back (use a flat trim tool gently if it’s stuck).
• Remove the protective rubber boot from the alternator B+ terminal.
• Use a 10mm socket to remove the terminal nut, then lift the main charge cable off and position it so it can’t touch metal.

Step 5: Remove the alternator mounting bolts

• Support the alternator with one hand so it doesn’t drop when bolts come out.
• Use a 12mm socket (and 6" extension if needed) to remove the alternator mounting bolts.
• Lift the alternator up and out of the engine bay.

Step 6: Install the new alternator

• Set the new alternator into place and start the mounting bolts by hand to avoid cross-threading.
• Tighten the mounting bolts using a 12mm socket and 3/8" ratchet, then final tighten with a 3/8" torque wrench: Torque to 36 Nm (27 ft-lbs).

Step 7: Reconnect the alternator wiring

• Reinstall the main charge cable onto the B+ stud and tighten the nut with a 10mm socket: Torque to 9 Nm (80 in-lbs).
• Reinstall the rubber boot over the terminal.
• Plug in the alternator connector until it clicks.

Step 8: Reinstall the accessory belt

• Route the new belt the same way as the old one (use your photo as a reference).
• Use a 14mm combination wrench to rotate the tensioner, slip the belt over the alternator pulley, then release the tensioner slowly.
• Verify the belt is fully seated in every pulley groove (a belt half-on can shred quickly).

Step 9: Reassemble and reconnect the battery

• Reinstall the intake ducting using a 10mm socket and clips with a flat trim tool.
• If raised, remove jack stands and lower the car with the floor jack.
• Reconnect the negative (−) battery terminal with a 10mm wrench and tighten snugly.

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✅ After Repair

• Start the engine and confirm there’s no battery/charging warning light.
• Listen for belt squeal or slapping sounds; shut off and re-check belt seating if you hear anything.
• If you have a multimeter, check charging voltage at the battery with the engine idling: typically around 13.5–14.8V.
• Do a short test drive, then recheck that the belt is still centered on the pulleys.

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💰 DIY vs Shop Cost

Shop Cost: $550-$1,050 (parts + labor)

DIY Cost: $180-$450 (parts only)

You Save: $370-$600 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-3.0 hours.

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🎯 Ready to get started?

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