This collection includes 3157 and 3156 LED bulbs, the solid-state upgrades of the OEM 3157 dual-filament bulb (27/8W) and 3156 single-filament bulb (27W) used in 12V automotive rear and signalling circuits. Both share the W2.5x16q wedge base with dual-side contact pads for push-in socket fitment, while differing electrically: 3157 supports dual-intensity channels (tail + brake or DRL + turn), and 3156 provides single-intensity output (reverse or turn-only).
LED replacements in this category preserve the OEM wedge geometry, contact orientation, and circuit mapping while converting filament emission to high-efficiency LED chips. Typical LED draw is ~2–6W equivalent, yet output ranges ~500–2000+ lumens (up to ~12000 lm in dedicated reverse kits). Many bulbs integrate CANbus load-emulation resistors or driver ICs to maintain correct BCM signalling behaviour and prevent hyperflash or bulb-out warnings.
Electrical & Base Attributes
- Voltage: 12V automotive compatible
- Base: W2.5x16q wedge push-in
- 3157 = dual-channel (low + high brightness)
- 3156 = single-channel
- OEM wattage: 3157 27/8W; 3156 27W
- LED equivalent: ~2–6W
- Brightness: ~500–2000+ lm (reverse kits up to ~12000 lm)
Because 3157 LED bulbs contain dual-channel drivers, they reproduce OEM dim tail / bright brake or DRL / turn separation, whereas 3156 LEDs provide single-mode signalling or reverse illumination. Physically similar bases create confusion: 3157 may operate in many 3156 sockets, but 3156 cannot provide dual-intensity 3157 function.
Lighting Functions Covered
- Brake & Tail (3157 red LED) — dual-brightness rear combo lighting
- Turn Signal (3156/3157 amber LED) — directional signalling circuits
- Reverse Light (3156 white LED) — high-lumen rear illumination
- Parking / DRL (3157 white LED) — running-light circuit
- Switchback (3157 white/amber) — DRL white → amber turn conversion
CK vs Standard Wiring Compatibility
A critical attribute in this category is 3157CK / 3156CK wiring, where the ground and signal pins are reversed relative to standard sockets. Vehicles from GM, Jeep, Ram, and Dodge frequently use CK circuits. LED bulbs must match wiring type; otherwise, brake/turn polarity errors or non-functionality occur. Many products here include non-polar or CK-compatible drivers to support both socket types, making 3157 the most commonly used in vehicles.
Optical & Housing Integration
3157/3156 bulbs operate in reflector-lens housings requiring 360° filament light distribution. LED versions use radial multi-chip arrays or 360° SMD layouts to replicate filament position and reflector fill, preventing hotspots and ensuring uniform brake/tail illumination.
CANbus & Hyperflash Control
Low LED current can trigger BCM error detection. Many bulbs include built-in resistors calibrated to ~27W halogen load signatures to maintain normal blink rate and eliminate hyperflash. Sensitive vehicles may still require external resistors.
Technology Variants in This Collection
- 3157 red brake/tail LEDs with resistors
- 3156/3157 amber turn signal LEDs
- 3156 white reverse LEDs (high-lumen kits)
- 3157 switchback white/amber LEDs
- 3156/3157 parking/DRL LEDs
- 360° SMD 3156/4156 LEDs
These LED upgrades provide complete rear lighting conversion through Underground Lighting, maintaining OEM wedge compatibility while increasing brightness, speed, and durability across brake, tail, turn, DRL, and reverse systems.
What's the difference between 3156 vs. 3157 LED Bulbs?
3156 and 3157 LED bulbs have slightly different functions, even though they look similar. The 3156 LED bulb is a single-function bulb commonly used in tail lights, reverse lights, and brake lights. The 3157 LED bulb, however, is a dual-function bulb designed for applications that need both low-intensity and high-intensity operation, like tail lights that double as brake lights or turn signals.
If you're looking to improve safety, customise your vehicle's lighting, or reduce maintenance costs, these LED light bulbs are a versatile and practical choice. Illuminate the road ahead with the brilliance of 3156 and 3157 LED bulbs for a brighter, safer, and more efficient journey.
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