Adding Load Resistors to Fix LED turn signal light bulbs from hyper flash
Many new cars like Audi, BMW, Lexus have adapted the new LED technology for turn signal lights, not only because of LEDs have sharper and brighter lighting output than stock filament bulbs, but also faster responding time than filament bulbs, so it will be easier to spotted from a further distance.
Because of this, more and more people have chosen to upgrade their cars with aftermarket LED turn signal light bulbs.
There are three most common types of aftermarket LED turn signal light bulbs below:
7440 (single filament) and 7443 (double filaments) wedge base LED light bulbs, which are usually used for Japanese vehicles like Honda, Nissan, Toyota.
3156 (single filament) and 3157 (double filaments) wedge base LED light bulbs, which are usually used for American vehicles like Ford, Dodge or Cadillac.
Finally, 1156 (single filament) and1157 (double filaments) bayonet base LED light bulbs, which are usually used for old Japanese cars and most European vehicles like Audi, BMW or Mercedes.
To find out which bulb is correct for your car, you can visit the LED Fitment Guide and follow this step by step guideline to figure out which bulbs will fit your vehicle.
When installing the LED turn signal light bulbs, almost everybody will encounter this problem that the LED turn signal light bulbs will flash much faster than stock corner light bulbs, the same symptom as one stock turn signal light bulb burnt out.
This so called "hyper flash" or "rapid flash" problem is caused when the total wattage for the turn signal light circuit drops because LED bulbs have a much lower wattage than stock filament bulbs. For example, a stock 7440 filament bulb is 21W, but a 7440 LED bulb ranges from only 0.5W up to 3W max.
In order to prevent the LED bulbs from "hyper flash" or "rapid flash", we will need to raise the wattage back to 21W.
The easiest and most common way to raise the wattage back is to parallel a piece of 50W 6Ohm load resistor to the turn signal circuit.
For 7440, 3156 and 1156 LED bulbs, since these are single filament bulbs, there are just one positive wire (Red or Blue) and one negative wire (Black or Brown). Therefore simply tap the two wires from the load resistors, one to positive and one to negative.
For 7443, 3157 and 1157 LED bulbs, since these are double-filament bulbs, therefore tap the load resistors to one positive and the negative wires, if the LED bulb still flash rapidly, simply tap the load resistor wire from the positive to another positive.
Since load resistors will generate heat, please make sure to mount the load resistors to the metal instead of the plastic.
For more detail about the installation, you can check the adding load resistor step by step DIY guide on iJDMTOY tech support page.
iJDMTOY carries large selection of 12V LED car bulbs, LED strip lights, LED under car lights and lighting accessories.
How Load Resistors Work
Do I Need Load Resistors?
Possibly not. The primary applications that require their use are in tail lights, turn-signals, and sometimes in side-markers and license plates. These cases are also often limited to higher-end vehicles that are more likely to have "bulb-out" warning features. This is a feature also found in, but not limited to, many newer model year German made vehicles.
Due to the large number of vehicle makes, years, models, and lighting applications, we are unable to provide a list of vehicles that will require load resistors. If you are unsure if your vehicle will need these for the light application in which you are interested, we recommend the following:
* Check your vehicle's owner's manual.
* Search online user forums.
* Purchase the bulbs. If you need load resistors, you can always get them later. :)
Some commen questions about load resistors
Why would I need a resistor - I am just changing a normal bulb for LED?
Load resistors are used when upgrading normal bulbs to LED. Because LEDs use much less power the indicator relay thinks that a bulb has blown and flashes rapidly as a warning. The relay is preset with a value of all the indicator bulbs on the vehicle and anything below this such as a blown bulb or replacing a bulb with a lower power consumption such as LED results in this warning of fast flashing. A resistor is required for EACH bulb changed to LED .
How do resistors work?
The resistor takes the power and converts it into heat which then creates the required load.
Why do I need a 50W when 25W is cheaper?
For indicators you need 50W. the resistors are rated at 50% of their capacity for continuous use. This means a 25W resistor is only rated at 12.5W for continuous use where the indicator you are replacing is 21W meaning the resistor will become dangerously overloaded. The seller of the underrated product will argue that the indicator flashes on and off so the resistor is not used constantly which is true, but this also means the resistor has between 0.3 and 0.5 seconds to cool in between flashes. So over a few seconds that resistor will become very hot. If you wait for your central heating to turn off and then touch the radiators TEN MINUTES later they will still be red hot! To be fair to the seller of the 25W resistor if they included a bespoke heatsink with the size calculated for each application and location, mounted the resistors using a thermally conductive paste then they would actually do the job. The last time we checked there was no such listing so 25W are not suitable for use in indicator circuits.
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Do you have any comments?
Nicebigfoot on January 04, 2015:
To prevent hyper flash turn signals I need to install resistors. Directions say to conect to pos and neg wires. Is it also acceptable to connect to chassis for ground wire?
Rubonix on December 26, 2014:
So i installed 3157 smds on my front turn signals and instead of hyper flash i get no blink at all should i try resistors btw it's a 1994 town car and when looking for the three wires i found four two black one brownish and one white with a stripe? Any idea which to splice into
cody on September 16, 2014:
I have a 98 dodge ram installed led bulbs in the tail lights and now my dash lights flash along with all my other bulbs when turn signal or brake pedal depressed installed load resistors for each bulb and still have the problem
ilovejdmtoy lm (author) on May 29, 2014:
@anonymous: You will need resistors
ilovejdmtoy lm (author) on May 29, 2014:
@joey-herber-1: You will need each load resistor for each LED bulb for turn signal lamps.
joey-herber-1 on May 28, 2014:
So do I need a single 50W 6ohm load resistor for the left and right turn signals or use 2 load resistors, 1 for each side?
martingallagher on February 27, 2014:
Great lens! Never thought of that.
anonymous on April 28, 2013:
michael story, I have no brake lights on my dodge truck. same thing that you talked about. bulb indicator coming on. using after market replacements on tail lights. but no brake lights. everything else works. can you help me.
grow-lite-store on April 08, 2013:
nice i am really impressed to read this out.
ilovejdmtoy lm (author) on March 24, 2013:
@anonymous: There are three wires, make sure you tap the load resistor to the positive wire of the turn signal, and the ground wire.
anonymous on February 25, 2013:
So if hyperflashing still occur, go positive to positive with the 3157 bullb?
anonymous on April 13, 2012:
Why do some new cars have LED running lights, but incandescent lamps for the turn signals?