A failed rear combination bulb on a 2017 Ford F-150 can remove the tail, brake or rear turn-signal function on one side. This guide covers trucks with the factory serviceable incandescent rear lamp and Ford-specified 3157 dual-filament bulb. It does not cover optional factory LED rear lamps, sealed aftermarket lamps or the separate 3156K reverse bulb. There is no dedicated OBD-II code that proves this bulb has failed, so verify the symptom and lamp type before ordering.
Easy to moderate
20–35 minutes for one side
$8–$20 for a two-pack; not a live price
Safety and scope
Park on firm, level ground, select Park, apply the parking brake and stop the engine. Switch all exterior lights off, keep the key away from the truck and allow the lamp to cool. Open and secure the tailgate before removing the lamp. This procedure keeps the truck on all four wheels; do not lift it.
Support the lamp as it releases. Do not let it hang from its wiring, pry against painted bodywork or pull sideways on the retaining tabs. Stop if the housing is cracked, the connector is heat-damaged, wires are exposed, water is pooled inside the lamp or the truck has a non-serviceable LED assembly. Those conditions require diagnosis or a different repair.
Featured replacement: exact 3157 two-pack
SYLVANIA 3157 Long Life Miniature Bulb, manufacturer part 3157LL.BP2, ASIN B01FWOD0X2. The selected variation is one retail pack containing two 3157 bulbs. Amazon’s item details identify “3157 Bulb (2)” as the included components. The package does not include sockets, seals, lamp housings, wiring, fasteners or tools.
Ford specifies a 3157 dual-filament bulb rated 27/8 watts for the incandescent rear, brake, rear direction-indicator and rear side-marker functions. Sylvania identifies 3157LL.BP2 as a two-pack of 3157 Long Life miniature bulbs. Confirm the truck has removable bulb sockets and the old bulb is marked 3157 before purchase.
Check the exact SYLVANIA 3157 two-pack on Amazon
Selection evidence: Amazon displayed “300+ bought in past week” for this exact ASIN on October 21, 2026. That rounded badge is an Amazon purchase indicator, not audited unit sales; the retrieved listing was a cached crawl reported as six days old. Availability and price can change.
Vehicle fitment and exclusions
| Application | Supported configuration | Important exclusion |
|---|---|---|
| 2017 Ford F-150, U.S./Canada owner-manual application | Factory rear combination lamp with removable socket and incandescent 3157 bulb. | Optional factory LED rear lamps are non-serviceable at bulb level. |
| Rear, brake, rear turn and rear side-marker functions | Ford lists 3157, 27/8W for these incandescent functions. | The reverse lamp uses 3156K, not the featured 3157. |
| Engine, cab, bed and drivetrain | Ford’s bulb procedure and chart do not divide this incandescent application by those attributes. | Modified wiring, aftermarket housings, other model years and export-market variations are outside this guide. |
The decisive check is the actual lamp: a serviceable unit has removable sockets behind the housing. If the lamp is marked LED, lacks the described socket or disagrees with the owner’s manual, stop and use a VIN-based Ford parts lookup or qualified service information. A generic online selector is not enough to override the installed equipment.
Diagnose the failed function first
Ask a helper to operate the brake pedal and turn signals while you stand safely to the side—never behind a truck that could move. Then deliberately switch the parking lamps on and compare left and right. Record which function is missing before shutting everything off. A 3157 has two filaments, so one function can fail while another still works.
- One side dark in one function: a failed filament is plausible. Confirm the other functions before opening the lamp.
- Both sides dark: do not assume two bulbs failed simultaneously. A fuse, switch, circuit or control issue may need diagnosis.
- Fast turn-signal flash: a burned filament is possible, but an open socket or wiring fault can produce a similar symptom.
- Flicker or intermittent operation: inspect for a loose bulb, spread terminals, corrosion, moisture or heat damage rather than repeatedly installing bulbs.
- New bulb remains dark: stop. The fault may be in the socket, connector, wiring, ground or upstream circuit. Do not bridge terminals or install a higher-rated fuse.
There is no dedicated engine OBD-II code for this bulb. A dashboard warning, if equipped, is not proof that the bulb itself is the failed component. Visible filament damage supports a bulb diagnosis, but an intact-looking filament does not prove the circuit is healthy.
Tools and supplies
| Tool or Supply | Exact Product | Product Link | Purpose and Selection Check |
|---|---|---|---|
| Required replacement bulb | SYLVANIA 3157LL.BP2, two-pack | Exact bulb pack | Matches Ford’s 3157, 27/8W incandescent specification. Not for the LED assembly or 3156K reverse position. |
| Required hand tool | Existing small ratchet and correctly fitting socket | No purchase link | Removes the two lamp bolts. Ford’s owner manual does not publish the bolt-head size; test-fit your socket fully and do not use an adjustable wrench. |
| Required handling material | Clean lint-free cloth or clean gloves already on hand | No purchase link | Keeps dirt off the new glass and protects the lamp finish. Do not add grease unless Ford service information for the exact socket calls for it. |
| Optional protection | Painter’s tape or a clean folded towel already on hand | No purchase link | Protects nearby paint while the housing is supported. Never use tape to hold a loose lamp or repair a broken tab. |
Estimated DIY and professional costs
DIY estimate: about $8–$20 for a 3157 two-pack, plus $0 if you already own a fitting socket, ratchet and clean cloth. This is a planning range, not a current Amazon price or local quote. Replacing both matching bulbs from the two-pack is optional; a working bulb need not be disturbed if the socket and lens are healthy.
Professional estimate: roughly $45–$130 for diagnosis and a simple bulb replacement, depending on local labor minimums and whether a socket or wiring fault is found. A damaged housing, LED assembly or electrical repair can cost substantially more. Ask whether diagnosis, parts and taxes are included.
Rear combination bulb replacement
- Confirm the failed side and lamp type. Complete the functional comparison described above, then switch all lamps and the ignition off. Look through the lens for ordinary incandescent bulb hardware. If the truck has the optional LED lamp, do not continue with this bulb procedure.
- Prepare the work area. Securely park the truck, open the tailgate and place the key away from the vehicle. Let the lamp cool. Put fasteners in a container so they cannot fall into the bed gap. Protect the painted edge if needed.
- Remove the two lamp bolts. With the tailgate open, identify the two bolts on the inner edge of the affected tail-lamp assembly. Seat the correctly fitting socket completely and loosen them with a small hand ratchet. Do not substitute pliers or an adjustable wrench.
- Release the housing. Hold the lamp with both hands and pull it carefully away from the tailgate pillar in the direction that releases its two retaining tabs. Keep the housing aligned; twisting or prying against the painted body can break a tab or damage the finish.
- Support and disconnect. Support the lamp so the harness is not carrying its weight. Disconnect the electrical connector as Ford directs. Press the actual locking feature; do not pull on the wires. Inspect for moisture, burned terminals, green corrosion or melted plastic before continuing.
- Remove the correct socket. Identify the brake/rear/direction-indicator socket rather than the separate reverse socket. Rotate the correct socket counterclockwise and withdraw it from the housing. If it is seized or distorted, stop rather than forcing it.
- Replace the 3157 bulb. Remove the old bulb from the socket using its straight-in base. Compare its number, base and contact arrangement with the new 3157 before installation. Seat the new bulb fully without bending contacts. Keep the glass clean and discard a bulb that is cracked or contaminated.
- Reinstall the socket and connector. Place the socket squarely into the housing and rotate it clockwise until its seal and locking tabs are fully seated. Reconnect the electrical connector until its latch engages. Make sure wiring is not trapped or stretched.
- Refit the housing. Align both retaining tabs with their body-side locations and press the assembly evenly into place. Reinstall both bolts by hand first to avoid cross-threading. Ford’s owner manual gives no numerical torque for these lamp bolts; tighten them evenly and snugly with a small hand tool without crushing plastic or stripping threads.
- Close out the repair. Remove tools, cloths and tape, then close the tailgate only after the lamp is secure and sitting flush. Do not drive with the tailgate open, loose fasteners or an unsecured housing.
No programming or relearn is required for a conventional bulb replacement. No suspension, fuel, pressurized, hybrid/high-voltage or lifting procedure is involved.
Final inspection and functional checks
Check that the housing sits evenly, both fasteners are present, the tailgate clears the lamp and no wiring is visible or pinched. Then stand to the side and have a helper operate the parking lamps, brake pedal and left/right turn signals. Compare brightness and flash rate with the opposite side. Confirm the reverse lamp still works separately.
Do not touch the housing or connector while powered. If any function remains dark, switches off intermittently or looks unusually dim, turn the lights off and recheck bulb seating and the connector once. Persistent trouble means the socket, ground, wiring, control circuit or lamp assembly needs diagnosis. Do not compensate with a larger fuse or higher-wattage bulb.
Common mistakes to avoid
- Ordering before checking LED versus incandescent: the 3157 does not repair Ford’s optional sealed LED lamp.
- Confusing the positions: the reverse bulb is 3156K; the featured 3157 is for the dual-intensity combination functions.
- Pulling the housing sideways: align the lamp with its two retaining tabs and never pry against paint.
- Letting the lamp hang by the harness: support it through every disconnected step.
- Cross-threading or overtightening: start bolts by hand and use a small hand tool. There is no owner-manual torque figure to guess.
- Skipping the multi-function test: one filament can work while the other has failed, so verify tail, brake and turn functions separately.
Frequently asked questions
Does one 3157 bulb handle the tail, brake and turn signal?
On the incandescent combination lamp, Ford lists a dual-filament 3157 at 27/8 watts for the rear, brake, rear direction-indicator and rear side-marker functions. Circuit logic and lamp construction determine which intensity is used.
Should I replace both sides?
The featured pack contains two bulbs. Replacing the matching bulb on the other side can be convenient when both are the same age, but it is not required to complete a safe one-side repair. Do not disturb a sealed LED lamp or a healthy socket simply to use the second bulb.
Can I use an LED retrofit bulb?
This guide does not validate LED retrofit compatibility, photometric performance, load behavior or legality. It covers the Ford-specified 3157 incandescent type. Factory LED rear lamps are a different assembly and are not serviceable with this bulb.
Why does the new bulb still not work?
Confirm that the correct socket and function were tested and that the bulb is fully seated. A damaged socket, connector, ground, fuse, wiring or control circuit can imitate bulb failure. Stop and obtain circuit-specific diagnosis rather than repeatedly installing parts.
What torque should I use on the tail-lamp bolts?
Ford’s 2017 owner manual procedure specifies removing and reinstalling the two bolts but does not publish a numerical torque. Start them by hand, tighten evenly with a small hand tool and stop when the lamp is secure. Do not invent a specification or use an impact wrench.
Sources and related Ford guides
- Ford 2017 F-150 Owner’s Manual, second printing: bulb replacement procedure on printed pages 338–339 and bulb chart on printed page 340.
- SYLVANIA 3157 Long Life Mini Bulb, 2 Pack: manufacturer identification and package format.
- Exact Amazon product listing for ASIN B01FWOD0X2; non-affiliate research link.
- Ford F-150 repair-guide hub and Ford F-150 chatroom. Include model year, lamp type and failed functions when asking for help.
- 2017 F-150 license-plate bulb replacement and 2017 F-150 front wiper-blade replacement.