This procedure covers replacement of tail light bulbs on the 2015-2020 Ford F-150, accessible from inside the truck bed without removing the entire lamp assembly.

Warnings

Tools required

Parts

• Tail light bulb × 1 — 3157 or 3157K for brake/turn, 921 for backup, verify in owner's manual

Preparation

1. Park vehicle on level surface and turn off all lights
2. Lower the tailgate for easier access to the tail light assembly access panels
3. Identify which bulb needs replacement (brake/turn signal, reverse, or tail light)

Procedure

1. 1

   Access the tail light assembly
   From inside the truck bed, locate the plastic access panel on the bed side wall directly behind the tail light assembly. The panel is positioned near the tailgate hinge area on each side.
2. 2

   Remove the access panel
   Remove the Phillips screws securing the access panel (typically 2-3 screws). Carefully pull the panel away from the bed wall to expose the back of the tail light assembly and bulb sockets.
3. 3

   Identify the correct bulb socket
   Identify the bulb socket that needs replacement. Upper socket is typically brake/turn signal (3157), middle is tail/running light (3157), and lower is reverse light (921). Socket positions may vary by trim level.
4. 4

   Remove the bulb socket
   Rotate the bulb socket counterclockwise approximately 1/4 turn and pull it straight out from the tail light housing. The socket should release with moderate pressure.
5. 5

   Remove the failed bulb
   For bayonet-style bulbs (3157), push the bulb in slightly and rotate counterclockwise to release. For wedge-style bulbs (921), simply pull the bulb straight out of the socket. Inspect the socket for any corrosion or damage.
6. 6

   Install the new bulb
   Insert the new bulb into the socket. For bayonet bulbs, align the pins, push in, and rotate clockwise until it locks. For wedge bulbs, push straight in until fully seated. Avoid touching the glass portion of the bulb.
7. 7

   Reinstall the bulb socket
   Insert the bulb socket back into the tail light housing, align the tabs, and rotate clockwise approximately 1/4 turn until it locks into place. Ensure the socket is fully seated.
8. 8

   Test the new bulb
   Before reinstalling the access panel, test the new bulb by turning on the appropriate light function (brake lights, turn signal, or reverse). Verify proper operation.
9. 9

   Reinstall the access panel
   Position the access panel back onto the bed wall and secure with the Phillips screws. Ensure the panel is flush and all screws are snug but not overtightened to avoid cracking the plastic.

Reassembly

1. Ensure the access panel is properly secured to prevent water intrusion
2. Close the tailgate and verify it operates normally without interference

Verification

• Turn on headlights to verify tail/running lights illuminate
• Have an assistant press the brake pedal to verify brake lights function properly
• Activate turn signals on both sides to verify proper operation
• Shift into reverse to verify backup lights illuminate (engine running, parking brake set)
• Visually inspect that all tail light functions work correctly and no warning lights appear on the dashboard

More procedures for this vehicle