Turn Signal Bulb - Rear

This procedure covers the replacement of the rear turn signal bulb in a 2011-2014 Ford F-150, accessed from inside the bed or through the taillight assembly.

Warnings

Tools required

Parts

• Rear turn signal bulb (3157A or 3157NA amber) × 1 — 3157A or 3157NA amber bulb

Preparation

1. Ensure the vehicle is parked on a level surface with ignition off
2. Determine which side requires bulb replacement (driver or passenger)
3. Allow taillight assembly to cool if vehicle was recently operated
4. Lower the tailgate for easier access to the taillight assembly

Procedure

1. 1

   Access the taillight assembly
   From inside the truck bed, locate the two plastic wing nuts or screws securing the taillight assembly from the rear. On some models, you may need to remove a small access panel. These are typically located along the inner bed wall behind the taillight.
2. 2

   Remove taillight assembly fasteners
   Rotate the two plastic wing nuts counterclockwise by hand or remove the screws using a Phillips screwdriver. Keep these fasteners in a safe location for reinstallation.
3. 3

   Pull taillight assembly rearward
   Gently pull the entire taillight assembly straight back away from the vehicle body. It is held in place by alignment pins and may require firm, even pressure. Do not force or pry excessively to avoid breaking mounting tabs.
4. 4

   Locate the turn signal bulb socket
   With the taillight assembly pulled away from the body, identify the turn signal bulb socket on the back of the assembly. The turn signal is typically the amber-colored lens section. The socket will have a wiring harness connected to it.
5. 5

   Remove the bulb socket
   Rotate the turn signal bulb socket approximately 1/4 turn counterclockwise and pull it straight out from the taillight housing. The socket and bulb will come out as one unit.
6. 6

   Remove the old bulb
   Press the bulb gently into the socket and rotate counterclockwise approximately 1/4 turn, then pull the bulb straight out from the socket. Inspect the socket for any corrosion, moisture, or damage.
7. 7

   Install the new bulb
   Using a clean cloth or gloves, insert the new 3157A amber bulb into the socket. Press gently and rotate clockwise approximately 1/4 turn until it locks into place. Ensure the bulb is fully seated and secure.
8. 8

   Reinstall the bulb socket
   Insert the bulb socket back into the taillight housing and rotate clockwise approximately 1/4 turn until it locks into position. Verify the socket is fully seated and secure.
9. 9

   Test the turn signal
   Before reinstalling the taillight assembly, turn the ignition to the ON position and activate the turn signal to verify the new bulb is functioning properly. Check for proper illumination and flashing rate.
10. 10

    Reinstall the taillight assembly
    Align the taillight assembly with the mounting pins on the vehicle body and push it firmly into place until it is flush with the body panel. Ensure the rubber seal is properly seated around the perimeter.
11. 11

    Secure the assembly
    From inside the bed, reinstall the two plastic wing nuts or screws and tighten them by hand or with a Phillips screwdriver. Ensure they are snug but do not overtighten plastic fasteners.

Reassembly

1. Ensure taillight assembly is fully seated and flush with body panel
2. Verify all fasteners are properly tightened
3. Check that rubber weather seal is properly positioned to prevent moisture entry

Verification

• Turn the ignition to ON and test both left and right turn signals to verify proper operation
• Activate hazard lights to confirm the new bulb flashes at the correct rate
• Visually inspect the taillight from outside the vehicle to ensure proper fitment and no light leaks
• Verify the taillight assembly is secure and does not rattle or move when pressed

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle