Tail Light Bulb

This procedure covers replacement of tail light bulbs on a 2015-2020 Ford F-150, accessed from inside the bed or via external housing removal.

Warnings

Tools required

Parts

• Tail light bulb (brake/turn signal) × 1 — 3157 or 3157K bulb, verify against existing bulb
• Tail light bulb (reverse light) × 1 — 921 bulb, if replacing

Preparation

1. Park vehicle on level surface and turn off ignition
2. Identify which bulb needs replacement (brake, turn signal, reverse, or running light)
3. Lower tailgate to access interior bed trim panels
4. Allow tail lights to cool for 5-10 minutes if recently used

Procedure

1. 1

   Access tail light assembly from bed interior
   From inside the bed, locate the plastic access panel on the forward bed wall directly behind the tail light assembly. The panel is held by push clips or Phillips screws depending on model year. Remove fasteners and pull panel away to expose the back of the tail light housing.
2. 2

   Locate target bulb socket
   Identify the correct bulb socket from the rear of the tail light assembly. Sockets are typically arranged with brake/turn signal at top, tail light in middle, and reverse light at bottom. Each socket is labeled or color-coded on the housing.
3. 3

   Remove bulb socket
   Grasp the bulb socket firmly and rotate counterclockwise approximately 1/4 turn (90 degrees) until it releases from the housing. Pull the socket straight out with the bulb still installed. Do not pull on the wiring harness.
4. 4

   Remove failed bulb from socket
   For wedge-base bulbs (168, 921), pull bulb straight out of socket with gentle wiggling motion. For twist-lock bulbs (3157), press bulb into socket slightly and rotate counterclockwise 1/4 turn, then pull straight out. Inspect socket terminals for corrosion or damage.
5. 5

   Install new bulb
   Using clean cloth or gloves to handle the new bulb, align bulb pins with socket slots. For wedge-base bulbs, push straight in until fully seated. For twist-lock bulbs, insert bulb and rotate clockwise 1/4 turn until locked. Ensure bulb is secure in socket.
6. 6

   Reinstall socket into housing
   Align socket tabs with housing slots and insert socket fully into tail light housing. Rotate clockwise 1/4 turn until socket locks into place. Verify socket is fully seated and cannot be pulled out without rotating.
7. 7

   Reinstall access panel
   Position bed access panel and secure with original push clips or Phillips screws. Ensure panel is flush with surrounding trim and all fasteners are properly engaged.

Reassembly

1. Verify access panel is completely secured and flush with bed wall
2. Close tailgate and ensure proper clearance with no interference

Verification

• Turn ignition to ON position without starting engine
• Activate parking lights to verify tail light function
• Press brake pedal to verify brake light operation
• Shift transmission to reverse to verify reverse light operation (engine running)
• Activate turn signals both left and right to verify proper flashing
• Visually inspect that no moisture has entered housing during bulb replacement

Related trouble codes on this vehicle

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