LED Turn Signal FAQ

Which LED color is good for turn signal lights?

Please note: “√” means legal color.
Application Xenon White Amber Yellow Brilliant Red Ultra Blue
Front Turn Signal Off Road Off Road
Rear Turn Signal Off Road Off Road
Backup Reverse Off Road Off Road
Brake/Tail Lights √ for red lens Off Road Off Road

What’s a T20 bulb?

A T20 bulb is commonly known by industry standards as the following bulb sizes: 7440 7441 7443 7444 992A, etc. These T20 bulbs are commonly used for the turn signals, tail/stop lights, reverse lights, and daytime running lights.; T20 bulb stands for 20mm width on the top of the bulb. Back to Top

automotive light bulbs T20

What is a T25 bulb?

A T25 bulb is commonly known by industry standards as the following bulb sizes: 3156 3056 3157 3057 3357 3457 4157, etc. These T25 bulbs are commonly used for the turn signals, tail/stop lights, reverse lights, and daytime running lights.T25 bulb stands for 25mm width on the top of the bulb. Back to Top


automotive light bulbs 3156 3157

What is a BA15 bulb?

The term BA15 means Bayonet base with 15mm in diameter. A BA15 bulb is commonly known by industry standards as the following bulb size: 1156 7506 7527 1157 2057 2357 7528 P21W P21/4W, etc. These BA15 bulbs are commonly used for turn signal, tail/stop lights, reverse lights and daytime running lights.  Back to Top

automotive light bulbs S25 single filament

I bought the LED lights for the backup reverse lights and it is dimmer than my stock, is that ok?

It should be ok because the backup reverse lights are meant to alert others so they know there is a car is reversing rather than actually illuminating the road. Also if you are unhappy with the output of the bulbs you can contact us and we can recommend a brighter option for you. Back to Top

Why do my LED turn signal lights hyper flash?

When your LED turn signals flash rapidly, that is known as “hyper-flashing”. The rate that they blink is roughly twice than the normal flash rate. This is because when you replace the stock turn signals with LED bulbs; due to their low power draw, the regular rate of power being given to the lights is more than enough to light them up which speeds up the blinker process. Although this will not damage your vehicle nor the LED bulbs, some people may find it a distraction and may want to have it blink at the regular rate. To have the LED bulbs blink at a regular rate, you would need to purchase load resistorsBack to Top

>What’s a switchback LED bulb?

A switchback means it has two colors (White and Amber) which can switch back and forth. It is commonly used to replace the double-filament bulbs for the front turn signal lights which can function as both parking position lights and turn signal lights. So this way you can have the parking position lights in a HID matching xenon white color and the turn signal lights in a street legal amber yellow color.

To sum up in order to install the switchback LED bulbs, you will need to make sure your front turn signal lights function for both turn signal and parking lights and the lens needs to be clear.     Back to Top

What is SRCK socket?

Please take a look at these two diagrams below. The conventional socket has positive terminals on both sides but the SRCK socket has positive terminals on the same side. So a non-SRCK compatible LED bulbs installed to a SRCK socket will cause a short resulting fuse-pop or even damage the LED bulb.However, don’t worry because JDM ASTAR LED bulbs are mostly SRCK compatible. Please check the notes before purchase to confirm whether CK compatible or not.

LED Fog Light FAQ

<<< Go Back

Which LED bulb should I use for my fog lights?

You would be able to use any LED bulb you would like as long as you get the correct size, if you are looking for functionality then we would recommend one of our headlight LED bulbs, if you are looking to just change the look of it and not care too much about how bright it is, then any bulb will do. Back to Top

Do I need resistors or decoders for LED fog lights?

This will all depend on the vehicle, some vehicles requires resistors or decoders and some will not, in most cases, american, german, korean, european, etc vehicles will require decoders or resistors due to their canbus system.  Back to Top

My new LED fog light bulbs are flickering what do I need to fix it?

If you are having flickering issues with your fog light bulbs then you would need resistors installed, also a relay harness will work as well since the relay harness will be drawing power from your battery instead of the circuit of the OEM fog light plugs. Back to Top

What color is legal for my vehicle?

Generally the only colors you should be using is either white or yellow, you would need to check with your local state laws to see what color lights are legal for fog lights.  Back to Top

How do I fix or remove condensation within my fog light housing?

If you have condensation within your fog light housing, this may mean that you have a crack or some sort of damage on the fog light itself. If you happen to see damage, the fog light housing must be replaced or the problem will keep happening. If you do not see any damages, you can remove the bulb and use a blow dryer to dry out the housing, once dried check your bulbs o-ring to see if it is worn out, replace the o-ring if needed. Back to Top

How do I know if I need resistors or decoders for my fog lights?

To find out if you need resistors or decoders for your fog lights is by removing ONE bulb and turning on your car and turning on your fog light, if you see any warning signs on your dash board or codes then you would need resistors or decoders.  Back to Top

>I installed your bulbs and now they do not turn on?

If you are having issues with the bulbs not turning on, we first would highly recommend checking your fuses, if the fuses are good next we would recommend putting back the stock bulbs to see if they light up, if they do light up then the bulbs may be defective, however we recommend installing the bulbs with resistors first before declaring the bulbs defective. If all else fails, please contact us right away and we will be able to assist you with any issues you are having.     Back to Top

Miniature LED Bulb FAQ

What does the miniature bulb refer to?

For auto led lights bulbs, miniature bulbs usually refer to the interior lights,license plate light,side marker light,or parking light.

The bulb size base includes T10, T15,  T5, BA9S, festoon D31(31MM), D36(36MM), D42(42MM),etc.Back to Top

What is a T10 or T15 wedge bulb?

T10 bulb stands for the 10mm width on the top of the bulb, nothing with the socket; T15 bulb stands for 15mm width on the top of the bulb:

T10 Base              T15 Base

A T10 bulb is compatible with  the original standard bulb size: W5W 147 152 158 159 161 168 184 192 193 194 259 280 285 447 464 501 555 558 585 655 656 657 1250 1251 1252 2450 2652 2921 2825 PC 175 2886X;

T15 bulb is compatible with the original standard bulb size 579 901 904 908 909 912 914 915 916 917 918 920 921 922 923 926 927 928 939. Back to Top

What is a 31mm/36mm/42mm bulb?

These bulbs are usually called “festoon” type bulbs with metal points a the end of the bulb. They are commonly used for replacing interior map dome lights,courtesy light,trunk light, or license plate lights.

31mm bulbs are compatible with the original standard bulb size  DE3175, DE3022, DE3021, 3021, 3022, 3175, 6428, 6430,etc.


36mm bulbs are compatible with the original standard bulb size 6418, 6411, C5W, DE3425, DE3423, 3423, 3425, 6461, 6423, 6486X, 7456, etc


42mm bulbs are compatible with the original standard bulb size a 578, 211-2, 212-2,214-2, 579, 6413, 6429, 4410, etc. Back to Top


What color is legal for my vehicle?

For interior lights, there us no restrictions about the color requirement, i.e, you can upgrade the interior lights any colors. Yet for exterior lights, it is recommended to check with your local laws. Here we  listed some common legally colors:

For the front of the vehicle: white,amber & yellow color are allowed

For the rear of the vehicle, white for license plate light,amber yellow and red for side marker light or center high mount stop light,etc.  Back to Top

What is the difference between polarity & non-polarity?

Many led bulbs in the market are polar sensitive, it requires the led bulbs positive must connect with 12V power positive or it will not light up.

So for the polarity bulbs, if the bulb doesn’t light up, please flip the bulb 180° degrees and try to install again.

Yet for the non-polarity bulbs, you will not worry about this polarity issue. no matter how you connect the bulb into the original socket, it will light up.

Most of our miniature bulbs are non-polarity bulbs for we have made a great improvement to make it more easier to install for the customers. Back to Top

How to tell which bulb is the brightest and best?

Usually for led bulb brightness, it is calculated by the light output lumens, the lumens is higher, the bulb bulb is brighter.

Yet please note, when you care of the lumens, also please care of the heat dissipation, for many led bulbs are bright in the market, but easily burned out,because the heat dissipation is bad.

Our miniature bulbs are built in IC driver to control the stable current, and built in better heat dissipation,which will makes the bulbs’ life span much longer.Back to Top

>What is a led bulb’s life span?

Logically, if the led bulbs works in perfect condition, it will last up to 50,000 hours, yet due to different factors , such as heat, voltage, weather, vehicle usage, or other factors, will shorten the led bulb’s life span. But usually the led bulbs will work about 20,000 hours in average.      Back to Top

LED Brake Light FAQ

What color should I use for brake lights?

The color for brake lights should be RED LEDs, white is acceptable if you don’t mind the pinkish hue to the lens and the lens is red lens. If it is white lens, only red is acceptable.

Do I need resistors for brake lights?
This will depend on the vehicle, if it throws a code on your dash or flickers then you would definitely need resistors to fix those issues

.Can I change the LEDs in my brake lights if they are already LED?

No, LED brake lights from factory will not be changeable like regular bulbs, however there are companies out there who do custom tail light work to make brake lights brighter or other custom jobs.

I changed my brake light bulbs to LED and they are not brighter?
This happens on different vehicles, when this happens, please contact us by clicking here, we will recommend the brighter bulbs for your own safety.

My Brake light fuse keeps popping?
Probably the socket type doesn’t match. There are 2 types of the socket, CK type and standard type. Please click here to check the difference. The standard type bulbs will pop out the fuse if plug into the CK type socket, it requires to purchase CK compatible led bulbs.


CAN Bus LED bulbs are simple plug-and- play LED bulbs which are made specifically for CAN Bus-equipped vehicles. These bulbs work with your vehicle’s advanced computer system, so when your vehicle’s computer reads them, they respond back correctly.

What does CAN Bus mean?

CAN Bus means Controller Area Network Bus. This system monitors your vehicle and reports operating conditions. CAN Bus systems are commonly found in European vehicles such as BMW, Audi, Mercedes, Volkswagen, Porsche, and in many American vehicles. While most late model American vehicles have CAN Bus systems, it is always good to check with your vehicle dealer to see which system your vehicle has before purchasing electrical products.

Will CAN Bus LED Bulbs Prevent “Bulb-Out” Indication?

Each vehicle has different requirements that the CAN Bus system is looking for, but in most cases CAN Bus LED bulbs should prevent a “bulb out” indication in areas such as tail, brake, and running lights. If you use a standard LED bulb that is not a CAN Bus application, you would consistently get a “bulb out” dashboard indicator because your system can’t communicate with a standard LED bulb.

Will CAN Bus LED Bulbs Prevent Hyper-Flashing?

CAN Bus bulbs will not prevent hyper-flashing of turn signals. These bulbs are communicating with the CAN Bus system, but the relay still needs an appropriate amount of load to operate correctly. Your electrical system could require load resistors or an electronic flashing relay to stop hyper-flashing. The factory relay causes the hyper-flash when it thinks there is not a bulb working.

Can you use CAN Bus LED bulbs in non-CAN Bus applications?

Yes, the can-bus led bulb can be used as non-Can Bus application.

General Knowledge about LED Bulbs

  1. What is an LED?
  2. How do I know how bright these LED bulbs are?
  3. What is color temperature and how do I match my headlamps with my fog lights?
  4. What is CK/SRCK and standard configuration and why should I check my sockets?
  5. What is a dual-filament bulb?
  6. What bulb size should I use?
  7. What color LED bulb should I use?
  8. Why is my bulb flickering/dimming as soon as I install them and turn them on?
  9. Why is my turn signal flashing faster than normal?
  10. What should I do if my LED bulbs do not fit?
  11. What is an LED ‘switchback’ bulb?
  12. What is an error-free LED bulb?
  13. How do I make the lamp out indicator go away?
  14. How do I check which LED bulb should be installed on my vehicle?

What is an LED?

An LED is a light emitting diode that is used in a variety of applications as a source of light.  When a suitable voltage is applied on to the two leads of a light emitting diode, it creates an effect known as “electroluminescence” which will result in a light source that is integrated on our products. Back to Top

How do I know how bright these LED bulbs are?

In the automotive industry, the brightness of an LED bulb is usually categorized by “luminous flux”(lumens) which is the unit of measurement of light that is visible to the human eye.  You should review the lumen rating to determine the total visible light output of the LED lamp. Back to Top

What is color temperature and how do I match my headlamps with my fog lights?

Color temperature refers to the color of the light emitted from the lamps.  The temperature of the light will determine the color of the light.  The color temperature is measured in kelvins(K) and should be considered when trying to purchase a specific color of LED lamps. Back to Top

What is CK/SRCK and standard configuration and why should I check my sockets?

Standard and CK/SRCK are two types of dual-filament(3157 & 7443) sockets for turn signal applications.  The ground terminals and leads are located in a different position and may cause a short on the circuit if the proper LED bulb is not installed.  You should contact your vehicles local dealer or test the sockets(using a test lamp) to determine what your vehicle is equipped with. Back to Top

What is a dual-filament bulb?

A dual-filament bulb is a lamp that supports to levels of light intensities; low and high intensity.  A good example will be a tail and brake light setup.  Tail light is the low intensity filament and brake light would be the high intensity filament.    Back to Top

What bulb size should I use?

The bulb size that should be used depends on the original bulb installed, or what the vehicle’s owner’s manual indicates for the application you are working on.  Most cases, you can easily identify the bulb size by simply consulting the owners manual.  You may also compare the factory bulb to our product to determine if it is suitable replacement size.  Back to Top

What color LED bulb should I use?

The color of the bulb should ALWAYS be within the legal limits of the laws of the road when operating an automotive vehicle.  You should go based off the part number on the bulb or even check the vehicles owners manual.  The manual and factory bulb will, usually, have a part number which indicates the type of filament bulb, bulb size and color(white, amber, or red). (Ex. 7444NA, & 3157A / NA=Natural A=Amber)  You should also consider the color of the lens on the housing assembly.  For safety, the color of the LED bulb should correspond to the color of the lens so that the color is vivid and noticeable to other drivers.  If the lens is clear, you should follow what the manual .  Back to Top

Why is my bulb flickering/dimming as soon as I install them and turn them on?

Some vehicles are equipped with a computer system that will monitor your vehicles lighting applications.  They are designed to notify a driver of problem or fault with the functionality of a lamp.  The system may recognize the low power draw of your LED bulb as a problem or fault.  It may cause a lamp out indicator on your dashboard and sometimes cause the lamp to flicker or dim because its recognizing the lamp as an open circuit(faulty/burned bulb).  A load resistor or decoder should be installed by tapping onto the ground and lead wires of the socket.  These components will ‘trick’ the computer system(CAN bus, BCM, etc. )into believing that you have a functioning bulb installed.            Back to Top

Why is my turn signal flashing faster than normal?

This is a very common malfunction with turn signal applications when upgrading to LED.  The issue is known as “hyper-flashing”.  Hyper-flashing occurs when the flasher relay(controls rate of flashing on the turn signals) cannot detect the power going to the turn signal.  Since LED bulbs are more efficient, there is a substantial decrease in power draw.  A load resistor should be installed on to the lead(turn signal) and ground wires.  Load resistors will simulate a power draw that resembles your factory halogen bulbs(20W-27W) to normalize the rate of flashing with your LED bulbs.  Another option, if possible, is to upgrade the factory flasher relay module with an electronic LED flasher relay which will work with a low power draw.  Factory equipped ‘thermal flasher relays’ cannot be upgraded so the proper load should be applied to the sockets using resistors.   Back to Top

What should I do if my LED bulbs do not fit?

This depends on the type of fitment issue you are experience.  You should consult your owners manual to confirm the size or part number.  The manual has information that your vehicles manufacturer has included and is more reliable than any other source, guide or reference available online.  You may also contact your local dealer to request the information.  If there is minimal labor involved, checking the factory bulb, and comparing it to the LED bulb you are trying to install is the best method to confirm that the bulb size(and dimensions) are accurate and suitable for your vehicle.  Once you have determined the reason for the fitment issue, you should install an LED bulb based off the information you have learned. Back to Top

What is an LED ‘switchback’ bulb?

An LED switchback(3030, PX, and EX series) bulb is like every other dual-filament LED bulb, but instead, support two filaments that have two different colors(Usually amber and white) for each filament rather than having the same color with two light intensities.  Our LED switchback bulbs will use white for the low intensity filament, and amber for turn signals.  For most vehicles, you will have a white color for parking/daytime running lights, and amber for the turn signal application.  Back to Top

What is an error-free LED bulb?

An error free LED bulb is an LED lamp that is CAN bus-ready.  This means that the bulb is equipped with either resistors(3W-5W) to simulate a larger power draw, or have built-in decoders(LED headlights) to increase starting amperage both of which the vehicles computer system(CAN bus, BCM, etc.) should detect.  This will ensure that the computer system does not recognize the lamp is a fault or an open circuit due to the low power draw, and will prevent minor malfunctions such as a lamp out indicator and even other common malfunctions that a CAN bus or similar system may cause.   Back to Top

How do I make the lamp out indicator go away?

A lamp out indicator may come up with any LED bulb depending on the vehicle and whether or not the vehicle is equipped with a CAN bus or similar computer system.  An error code may be triggered if your vehicle cannot detect the LED bulb that is installed on the socket.  A load resistor or decoder should be installed to the lamp that is causing the error code.  These components will ‘trick’ the computer system into believing you have a functioning “halogen” bulb installed rather than a low power draw LED lamp and thus correct the malfunction. Back to Top

How do I check which LED bulb should be installed on my vehicle?

This depends on the type of vehicle whether American, European, Japanese, and/or Korean.  The bulb you choose should be based off the factory bulb and/or owners manual.  European and American vehicles may require certain types of LED bulbs that offer error free capabilities for vehicles like GM, Ford, Jeep, Chevrolet, as well as Audi, BMW, Mercedes-Benz, Jetta, Mini, Porsche etc.  You then need to consider the features/hardware of the LED bulbs to determine if they are a suitable replacement for the application you are upgrading.  The last factor that will help determine the right LED bulbs is the color and light output.  The owners manual and color of the lens should determine the correct color of the LED bulb.   Back to Top

How can I find the correct bulb size for my vehicles?

Have you have had a moment where you are driving down a roadway, and drivers keep flashing there lights, or honking there horn to alert you?  Your headlights are on, but there is no “lamp out” indicator so you assume everything is okay, but then you pull off to the side of the road, and you realize one of your headlights is out.  Now you have to contact your local dealer, or auto parts store, and speak to somebody, get placed on hold and listen to the, “oh so lovely”, music that you hear in an elevator.  What ever the case is, you just do not have time to go through steps to get the information you need to replace your lamp.

Our JDMASTAR.COM website features a user friendly guide(pls check the below button) which allows you to identify what part your vehicle requires for the main lighting applications.  You do not have to pick up a phone, or listen to any lovely elevator music.  Simply input your vehicle information like the year, the maker of your vehicle, model, and type or trim.  Upon doing so, our tool will generate the information you are looking for so that you know what size to buy.  The tool will list the bulb sizes for almost all lighting applications in your vehicle.  The tool will guide you to make sure you are buying the correct bulb size for your vehicles application.  After retrieving the information, pop out the traditional owners manual and confirm it.  Then click on the suggested listing, that is designed for the application you are using, and “voila!” You are now just one step away from making your driving experience even safer!

Find Bulbs