🔧 3 - Taillight Bulb Replacement

On your 3, the rear bulbs are accessed from inside the trunk, behind the trunk side trim/access covers. You’ll remove the bulb socket(s), swap the bulb(s), then reinstall everything so the lamps seal properly and don’t let water in.

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

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⚠️ Safety & Precautions

• ⚠️ Turn the lights OFF and remove the key before starting.
• ⚠️ Let bulbs cool first; they can burn you.
• ⚠️ Don’t touch the glass of a new bulb with bare fingers; oils can shorten bulb life.
• ⚠️ If you find your taillights are LED (no removable bulb), the bulb is not serviceable and the lamp assembly must be replaced.

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🔧 Required Tools

You'll need the following tools for this repair:

• Nitrile gloves
• Safety glasses
• Plastic trim removal tool
• Phillips screwdriver #2
• 10mm socket
• 1/4" drive ratchet
• Small flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Rear lamp bulb(s) (match type printed on old bulb) - Qty: 2
• Trunk trim clips (optional, in case any break) - Qty: 2-6

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📋 Before You Begin

• Park on level ground and open the trunk.
• Turn the light switch to OFF and remove the key from the vehicle.
• Set aside a small container for clips/screws so nothing gets lost.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Confirm which bulbs you’re replacing

• Use the flashlight and have someone press the brake / turn signal if needed.
• Common rear functions are tail/running light, brake light, turn signal, and reverse light.
• Tip: Replace left and right in pairs.

Step 2: Open the trunk and access the lamp area

• On the side you’re working on, locate the trunk side trim access cover (or the trim panel area behind the lamp).
• Remove any access cover fasteners using a Phillips screwdriver #2.
• If the trim is clipped in, gently pop clips using a plastic trim removal tool (a trim tool is a plastic pry tool that helps prevent scratches).

Step 3: Remove the bulb socket

• Reach behind the taillamp and find the bulb socket for the failed bulb.
• Twist the socket counterclockwise by hand and pull it straight out.
• If access is tight, reposition the trim more using the plastic trim removal tool.

Step 4: Replace the bulb

• Pull the old bulb straight out of the socket (some types twist to unlock; if it resists, try a gentle twist and pull).
• Put on nitrile gloves, install the new bulb fully into the socket.
• Match the replacement bulb to the number printed on the old bulb base (example format: “7440”, “7443”, “921”, etc.).

Step 5: Reinstall the socket and test

• Reinsert the socket into the lamp housing and twist clockwise by hand until it stops.
• Turn the lights on and test that function before reinstalling trim.
• If it doesn’t light, remove and reseat the bulb and socket.

Step 6: Reinstall trunk trim/access cover

• Reinstall any clips by pressing them in by hand.
• Reinstall screws using a Phillips screwdriver #2.
• If you removed any 10mm nuts for trim retainers, reinstall with a 10mm socket and 1/4" drive ratchet; Torque: N/A (snug only—do not overtighten plastic trim).

Step 7: Repeat on the other side

• Do the same procedure for the other taillight so both sides match brightness and color.

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✅ After Repair

• Verify tail lights, brake lights, turn signals, and reverse lights all work.
• Make sure the socket is fully seated to prevent water leaks and condensation inside the lamp.
• If a bulb immediately fails again, the socket may be heat-damaged and should be replaced.

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💰 DIY vs Shop Cost

Shop Cost: $80-$180 (parts + labor)

DIY Cost: $10-$40 (parts only)

You Save: $70-$140 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.

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Two quick questions so I can tell you the exact bulb types:

• Which bulbs are out: brake, tail/running, turn signal, reverse, or all?
• When you remove one bulb, what number is printed on the bulb base (example: 7440/7443/921)?