Quick Answer
One package of the compatible F-150 Rear Turn Signal, Brake & Tail Light product contains two red 3157 LED bulbs. One package normally upgrades one corresponding left-and-right rear-light position.
- Upgrade the left and right rear turn signals: 2 bulbs, or 1 package.
- Upgrade the left and right shared brake/tail lights: 2 bulbs, or 1 package.
- Upgrade separate rear turn-signal and brake/tail-light positions: 4 bulbs, or 2 packages.
- Reverse lights require separate fitment confirmation and are not part of the red 3157 package.
Before selecting one or two packages, confirm whether the rear turn signal and brake/tail light use the same bulb position or two separate bulb positions on your truck.
How Many Bulbs Are Included in One Package?
One package contains two red 3157 LED bulbs.
The two bulbs are intended to upgrade one matching left-and-right lighting position:
- One bulb for the left side
- One bulb for the corresponding right side
A two-bulb package does not normally represent two different positions inside one tail-light assembly.
How Many 3157 Bulbs Are Needed for the Rear Turn Signals?
If the truck uses one replaceable 3157-series rear-turn-signal bulb on each side, the quantity is:
- Left rear turn signal: 1 bulb
- Right rear turn signal: 1 bulb
- Total: 2 bulbs
- Suggested quantity: 1 package
After installation, test the left turn signal, right turn signal and hazard lights before reinstalling the tail-light assemblies.
Why Should Both Rear Turn Signals Be Replaced Together?
Replacing both sides helps maintain:
- Matching red color
- Similar brightness
- Consistent flash response
- Balanced electrical operation
- A consistent rear appearance
Mixing one LED bulb with one older halogen bulb may create visible differences in brightness, color and response time.
How Many Bulbs Are Needed for the Brake and Tail Lights?
Brake and tail-light functions often share one dual-intensity 3157 bulb on each side.
In a shared brake/tail-light position:
- The lower-intensity mode operates as the tail light.
- The higher-intensity mode operates as the brake light.
The quantity is normally:
- Left brake/tail light: 1 bulb
- Right brake/tail light: 1 bulb
- Total: 2 bulbs
- Suggested quantity: 1 package
When Does a Ford F-150 Need Four 3157 Bulbs?
Four bulbs are normally required when the truck uses:
- One separate rear-turn-signal bulb on each side, and
- One separate shared brake/tail-light bulb on each side.
The total becomes:
- 2 bulbs for the left and right rear turn signals
- 2 bulbs for the left and right brake/tail lights
- Total: 4 bulbs
- Suggested quantity: 2 packages
| Upgrade Goal | Bulbs Required | Packages Required |
|---|---|---|
| Left and right rear turn signals | 2 bulbs | 1 package |
| Left and right brake/tail lights | 2 bulbs | 1 package |
| Rear turn signals plus brake/tail lights | 4 bulbs | 2 packages |
| One failed rear bulb | 1 bulb | Replacing both sides is recommended |
| Reverse lights | Confirm separately | Not included in the red 3157 package |
Are the Rear Turn Signal and Brake Light Always Separate?
No. Rear-light layouts can differ by vehicle configuration and tail-light design.
Separate Turn-Signal Position
One bulb flashes as the rear turn signal, while another bulb operates as the shared brake/tail light.
Upgrading both functions on both sides normally requires four bulbs.
Combined Turn and Brake Position
Some rear-light systems use the same red light section for both braking and turn signaling.
In this arrangement, fewer separate bulb positions may be present.
Shared Brake and Tail Position
One dual-intensity bulb operates at lower intensity as a tail light and higher intensity as a brake light.
Integrated LED Assembly
A factory integrated LED tail light may not contain removable 3157-series bulbs at all.
This is why quantity should be confirmed from the truck’s actual tail-light assembly rather than from the model year alone.
How Do You Confirm Whether You Need One or Two Packages?
Confirm the Tail Light Uses Replaceable Bulbs
Inspect the rear of the housing for removable twist-lock bulb sockets. An integrated LED assembly may not accept a 3157 replacement.
Activate the Rear Turn Signals
Test the left turn signal, right turn signal and hazard lights. Identify the section that flashes.
Activate the Tail Lights
Turn on the parking lights or headlights and identify the section that stays illuminated at lower intensity.
Activate the Brake Lights
Have another person press the brake pedal and observe which section changes to a higher intensity.
Compare the Illuminated Positions
If the rear turn signal and brake/tail light illuminate in two separate areas, the truck likely uses two bulb positions per side.
Remove and Read the Original Bulbs
Check the bulb numbers in both positions before ordering. Do not assume that every rear bulb uses the same base.
Why Can Quantity Differ Between Trucks from the Same Year?
Two Ford F-150 trucks from the same model year may not have identical tail-light systems.
Differences may be caused by:
- Trim level
- Factory lighting package
- Replaceable-bulb or integrated LED tail lights
- Special-edition lighting configurations
- A previously replaced tail-light assembly
- Aftermarket tail lights
- Different bulb layouts within the housing
If an aftermarket tail-light assembly has been installed, use the bulb and socket currently inside that assembly as the fitment reference.
Does One 3157 Bulb Handle Both Brake and Tail-Light Functions?
It can, when installed in a compatible dual-intensity socket.
The two operating levels are generally:
- Low intensity: steady tail-light operation when the parking lights or headlights are on
- High intensity: brighter brake-light operation when the brake pedal is pressed
This means that a truck does not normally need one bulb for the brake light and another bulb for the tail light when both functions share the same socket.
Are Reverse Lights Included in the 3157 Red-Bulb Quantity?
No. Reverse lights should be confirmed separately.
Reverse lights generally:
- Produce white light
- Activate only when the truck is shifted into reverse
- May use a different bulb number
- Require a separate product and fitment check
Do not include reverse-light quantity when calculating how many red 3157 bulbs are needed for rear turn, brake and tail-light positions.
Should You Replace Only One Failed Bulb?
It is physically possible to replace one failed bulb, but replacing the left and right bulbs as a pair is generally more practical.
Pair replacement helps maintain:
- Matching color
- Similar output
- Consistent response time
- Balanced appearance
- Simpler troubleshooting
Keeping the remaining bulb from the package as a spare is also possible, but the installed left and right sides may not match if one side remains an older halogen bulb.
Why Does Bulb Color Matter When Ordering Quantity?
The number of bulbs is only useful after the correct bulb color has been confirmed.
Common rear-light colors include:
- Red: brake lights, tail lights and some rear turn signals
- Amber: some dedicated rear-turn-signal positions
- White: reverse lights
A red 3157 package should only be counted for positions that require red output.
Does CANbus Compatibility Change the Number of Bulbs Needed?
CANbus compatibility does not normally change the physical quantity. A left-and-right position still requires two bulbs.
It does affect whether the LED bulbs operate correctly after installation. An incompatible LED turn-signal bulb may cause:
- Hyper flash
- Dashboard bulb warnings
- Different left and right flash speeds
- Intermittent operation
- The need for additional load resistors
Install matching products on both sides and test the complete function before reinstalling the tail-light housings.
What Should Be Tested After Installing One or Two Packages?
Rear Turn Signals
- Left signal flashes normally
- Right signal flashes normally
- Hazard lights operate normally
- There is no hyper flash
- There are no persistent warnings
Tail Lights
- Both sides illuminate at low intensity
- Left and right color matches
- There is no flicker
- The bulbs remain steadily illuminated
Brake Lights
- Both sides switch to high intensity
- The high- and low-intensity difference is clear
- The third brake light also operates
- Both rear sides respond at the same time
Final Installation
- All bulbs are fully inserted
- All sockets are locked
- The seals remain correctly positioned
- No wiring is pinched
- Both housings are securely reinstalled
Lasfit D2 Series Red 3157 LED Bulb Quantity
The compatible 3157 led bulbs are supplied as a two-bulb package.
Use the following purchase logic:
- One package: one matching left-and-right rear-light position
- Two packages: separate rear-turn-signal and brake/tail-light positions on both sides
The product-page specifications include:
- Two bulbs per package
- Red output
- 3157-series compatible bulb references
- CANbus-ready design
- Non-polarity installation
- Plug-and-play factory-socket replacement
- 360-degree illumination
- Frosted diffuser
- Aluminum cooling body
3157 Bulb Quantity Checklist
Tail-light layout
- The housing uses removable bulbs.
- The rear-turn-signal position has been identified.
- The brake/tail-light position has been identified.
- It is clear whether the two functions use separate bulbs.
Bulb fitment
- The original bulb numbers have been checked.
- The target positions use compatible 3157-series sockets.
- The required output color is red.
- The truck does not use an incompatible aftermarket housing.
Purchase quantity
- One left-and-right position requires two bulbs.
- Two separate left-and-right positions require four bulbs.
- Reverse lights have been excluded from the red-bulb quantity.
- Left and right bulbs will be replaced together.
Installation test
- Left and right turn signals flash normally.
- Hazard lights operate normally.
- Tail-light low-intensity mode works.
- Brake-light high-intensity mode works.
- There are no persistent warnings or hyper flash.
Frequently Asked Questions
How many 3157 bulbs are in one package?
One package contains two bulbs. It normally upgrades one corresponding left-and-right rear-light position.
Do I need one or two packages for the rear turn signals?
If each side uses one compatible rear-turn-signal bulb, one two-bulb package normally covers both sides.
How many bulbs are needed for the brake and tail lights?
If the brake and tail functions share one dual-intensity bulb on each side, two bulbs, or one package, normally cover both sides.
When do I need four 3157 bulbs?
Four bulbs are normally required when the rear turn signals and brake/tail lights use two separate bulb positions on both sides.
Does one 3157 bulb work as both a brake and tail light?
Yes, in a compatible dual-intensity socket. The lower-intensity mode functions as the tail light, while the higher-intensity mode functions as the brake light.
Are the reverse-light bulbs included?
No. Reverse lights normally require white output and may use a different bulb number. They should be confirmed separately.
Should I replace both sides if only one bulb has failed?
Replacing both sides helps maintain matching color, brightness and response. One package already contains a left-and-right pair.
Do all 2015–2020 Ford F-150 models need the same quantity?
No. Quantity depends on the actual tail-light layout, factory lighting system and whether the truck has replaceable bulbs, integrated LEDs or aftermarket assemblies.
Can I use one package for one side of the truck?
The package contains two bulbs, but the intended quantity logic is normally one bulb for the left side and one for the corresponding right side. Using both bulbs on one side would leave the matching position on the other side unchanged.
Does CANbus compatibility reduce the number of bulbs required?
No. CANbus compatibility affects electrical operation, not the physical quantity. One left-and-right position still requires two bulbs.
Conclusion
The number of 3157 LED bulbs required depends on how many separate replaceable rear-light positions are being upgraded.
- Rear turn signals only: 2 bulbs, or 1 package
- Brake/tail lights only: 2 bulbs, or 1 package
- Separate rear turn and brake/tail positions: 4 bulbs, or 2 packages
Before ordering, confirm the tail-light assembly type, original bulb numbers, required color and whether the turn and brake/tail functions use the same or separate sockets.
One package should be understood as one matching left-and-right pair. Once the truck’s rear-light layout has been confirmed, the correct quantity becomes much easier to determine.