🔧 F-350 Super Duty - Rear Turn Signal Bulb Replacement

Your rear turn signal bulb sits inside the tail lamp assembly. Replacing it means removing the tail lamp, swapping the bulb, and then testing the signals to confirm it flashes correctly.

Difficulty Level: Beginner | Estimated Time: 0.3-0.7 hours

---

⚠️ Safety & Precautions

• ⚠️ Turn ignition OFF and remove the key before starting.
• ⚠️ Make sure the lights are OFF and the hazard flashers are OFF.
• ⚠️ Wear gloves; bulbs can get hot and oils from fingers can shorten bulb life.
• ⚠️ Do not pry against painted body panels; the tail lamp releases straight rearward.
• Battery disconnect is not required for this repair.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 8mm socket
• 1/4" drive ratchet
• 3" extension (1/4" drive)
• Plastic trim removal tool
• Nitrile gloves
• Safety glasses

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Rear turn signal / stop bulb (3157 type) - Replace in pairs - Qty: 2

---

📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Open the tailgate to access the tail lamp fasteners.
• Lay a towel on the bumper corner to prevent scratches when handling the lamp.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Open access and remove the tail lamp screws

• Open the tailgate.
• Use an 8mm socket with a 1/4" drive ratchet and 3" extension to remove the two tail lamp retaining screws on the inboard side of the tail lamp.
• Set the screws aside somewhere safe.
• Torque to 2 Nm (18 in-lbs) during reassembly.

Step 2: Remove the tail lamp assembly

• Grab the tail lamp housing with both hands and pull it straight rearward.
• If it feels stuck, use a plastic trim removal tool to gently help it release from the locator pins. (A trim tool is a plastic pry tool that helps pop clips loose without damaging paint.)
• Pull straight back; don’t twist the lamp.

Step 3: Remove the turn signal bulb socket

• Locate the turn signal/stop bulb socket on the back of the tail lamp.
• Twist the socket counterclockwise by hand and pull it out of the housing.

Step 4: Replace the bulb

• Put on nitrile gloves.
• Pull the old bulb straight out of the socket.
• Push the new 3157 type bulb straight into the socket until fully seated.
• Don’t touch the glass with bare fingers.

Step 5: Reinstall the socket and tail lamp

• Insert the socket back into the tail lamp and twist clockwise until it locks.
• Align the tail lamp locator pins with the body grommets and push the tail lamp straight in until fully seated.
• Reinstall the two screws using the 8mm socket, ratchet, and extension.
• Torque to 2 Nm (18 in-lbs).

Step 6: Repeat on the other side

• Repeat Steps 1–5 for the other rear turn signal bulb.
• Replacing both keeps brightness and color even.

---

✅ After Repair

• Turn ignition ON.
• Test left and right turn signals.
• Test brake lights (have someone press the brake pedal or back up near a wall to see the reflection).
• If you get fast-flashing, re-check that the bulb is fully seated and the socket is fully locked.

---

💰 DIY vs Shop Cost

Shop Cost: $60-$140 (parts + labor)

DIY Cost: $10-$30 (parts only)

You Save: $50-$110 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.3-0.7 hours.

---

🎯 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.