Tail Light Bulb

This procedure covers the replacement of tail light bulbs on a 2011-2014 Ford F-150, including removal of the tail light assembly from the rear of the vehicle.

Warnings

Tools required

Parts

• Tail light bulb (3157 or 3157K for brake/turn signal) × 1 — 3157 or 3157K depending on position
• Tail light bulb (921 for backup light) × 1 — 921 white bulb

Preparation

1. Determine which bulb needs replacement (brake, turn signal, reverse, or tail light)
2. Park vehicle on level surface and turn off ignition
3. Open tailgate for access to tail light assembly mounting bolts

Procedure

1. 1

   Access tail light assembly
   Open the tailgate fully. Locate the two 7mm mounting bolts securing the tail light assembly to the bed side. These bolts are accessible from inside the bed with the tailgate open, near the rear edge of the bed rail.
2. 2

   Remove tail light assembly bolts
   Using a 7mm socket and ratchet, remove the two mounting bolts that secure the tail light assembly. Keep these bolts in a safe location for reinstallation.
3. 3

   Pull tail light assembly rearward
   Carefully pull the tail light assembly straight rearward away from the vehicle body. The assembly is held by clips in addition to the bolts, so steady firm pressure may be required. Do not pry or twist excessively to avoid breaking mounting tabs.
4. 4

   Rotate bulb socket counterclockwise
   Identify the bulb socket that needs replacement on the back of the tail light assembly. Rotate the appropriate bulb socket approximately 1/4 turn counterclockwise and pull it straight out from the housing.
5. 5

   Remove failed bulb
   For wedge-type bulbs (921 reverse lights), pull straight out from socket. For bayonet-type bulbs (3157 brake/turn/tail), press bulb in slightly and rotate counterclockwise to release, then pull out.
6. 6

   Install new bulb
   Using a clean cloth or wearing gloves to avoid touching the glass, insert the new bulb into the socket. For bayonet-type bulbs, press in and rotate clockwise until it locks. For wedge-type bulbs, push firmly into socket until fully seated.
7. 7

   Reinstall bulb socket
   Insert the bulb socket back into the tail light assembly housing and rotate clockwise approximately 1/4 turn until it locks into place. Gently tug on the socket to confirm it is secured.
8. 8

   Reinstall tail light assembly
   Align the tail light assembly with the mounting holes and guide pins on the vehicle body. Push the assembly firmly forward until it seats flush against the body and the mounting holes align.
9. 9

   Install mounting bolts
   Thread both 7mm mounting bolts by hand to prevent cross-threading, then tighten securely with a socket and ratchet. Ensure the assembly is seated properly and does not have gaps around the edges.

Reassembly

1. Ensure tail light assembly is flush with body panels and properly sealed to prevent water intrusion
2. Close tailgate and verify proper clearance with tail light assembly

Verification

• Turn ignition to ON position and test all tail light functions: running lights, brake lights, turn signals, and reverse lights
• Have an assistant observe lights from rear of vehicle or use a reflective surface to confirm proper operation
• Verify no moisture or condensation is present inside the tail light housing

Related trouble codes on this vehicle

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