LED Turn Signal Lights Bulbs FAQ

Color options as below to show which application is legal to use for most states in USA.

T25 bulb is T25 wedge base, the diameter for the top base is about 24.00mm. It has 2 types: one is with 2 filaments like 3157, the other is with 1 filament only like 3156. This is a type of bulb that is associated with the following sizes: 3156 3056 3157 3057 3357 3457 4157, etc. Used for replacing: Turn signals, tail/stop lights, reverse lights, and daytime running lights.

This type of bulb has a bayonet base of 15mm in diameter, and the type of bulb is associated with industry standard sizes: 1156 7506 7527 1157 2057 2357 7528 P21W P21/4W, etc. Used for: Turn signal, tail/stop lights, reverse lights and daytime running lights.

The purpose of the reverse light is not to illuminate the road, but rather to alert others that a car is being reversed, so it’s completely okay. Just make sure the white light is visible!

This commonly known occurrence is called “hyper flashing”. It happens when the rate of the blink is about twice the rate of the stock or the normal flash rate. When the stock bulbs are replaced with the aftermarket LED bulbs, the regular rate of power is more than enough to what is required by the LED bulbs to light them up, thus, the blink process is sped up. Although this is not harmful to the car, or the bulb, it can be distracting and people generally want it to blink at the normal rate. The solution is quite simple – just use a load resistor.

It is recommended to keep the stock bulbs for tail lights – unless they are broken or no longer work. This is because most, if not all, tail lights have a red lens covering the bulb. Due to this red lens, the output of the aftermarket LED bulb would not be as good as it will be in a clear housing. It’s fair to say that LED bulbs just look better when they are inserted under a housing that is already clear, such as reverse back up lights, or front and rear turn signals, as opposed to the red lens housing covering the bulbs for tail lights.

These types of bulbs contain two colors – White and Amber, and they can be switched back and forth. They are used for double filament bulbs that have two functions, such as the double filament bulb for the front turn signal lights. These lights have both the parking position lights, as well as the turn signal lights. And as you may already know, both are different colors. Parking position light should be white, and the turn signal yellow. 

Double-Filament bulbs are simply bulbs that have two filaments. Usually they are manufactured in such a way that one filament gives out brighter light than the other. Double-filament bulbs are also used at the rear end of the car. This particular bulb may be shared by the car’s stop light and tail light. The tail light provides the red light at the rear end of the car and usually this serves as the low beam part of the double-filament bulb. The brighter high beam is intended as the stop light and this will illuminate every time the driver presses his/her foot on the brake pedals. These stop lights are also called brake lights.

T20 bulb is T20 wedge base, the diameter for the top base is about 20.00mm. It has 2 types: one is with 2 filaments like 7443, the other is with 1 filament only like 7440. This is a type of bulb that is associated with the following sizes: 7440 7441 7443 7444 992A W21W WY21W, etc.  Used for replacing: Turn signals, tail/stop lights, reverse lights, and daytime running lights.

Switchback LED bulbs are designed to only work with dual filament housing such as 1157, 3157, and 7443, so the answer is no.

Generally, there are two basic types of bulb sockets that exist in any car, namely, SRCK and standard. The major difference between a standard and SRCK type is the position of the contacts at the ground. Though both sockets look alike, there is a significant difference in the placement of the ground contacts. Once you have found the type of bulb opening fitted in your car, you can easily shop for the complete Non-polar SRCK/Regular compatible LED bulbs to light up your car, both in terms of looks and utility. If you buy the LED bulbs without having the knowledge about your bulb socket types, you might end up damaging the entire lighting setup in your car as the protective fuse may blow.