For your viewing pleasure, I've done a short video showing a single LED connected to an unmodified flasher relay then the same LED connected to the modified relay :

Modified Flasher Relay Demo

 

Nice accent. Have I hit you up for any scotch yet?

 

I appreciate your effort.

A couple of comments:

First - as you said - one of the reasons for hyperflashing is you get indication that a bulb is burnt out - this mod eliminates that, although if you replace ALL the turn signal bulbs with LED's, it probably doesn't matter.

Second - Personally, to me the main advantage to LED's isn't so much the lower wattage as the faster turn on and turn off sign - there is a much sharper cutoff, so the bulbs look more dramatic and are more likely to be noticed.

 

Or, as we found out when someone sideswiped my daughter's 2011 Sonata and smashed a taillight, depending on model, you can replace the whole tail light assembly with cool led ones that don't have that problem. Amazon.com: VLAND LED Tail Lights Compatible for Hyundai Sonata i45 YF 6th Gen Sedan 2011 2012 2013 2014, Smoked lens style, Not For Factory LED version, Halogen version only : Automotive

 

Great post! very useful information!


So,.... if I want to DELAY the switching on/off of my turn signal (to allow a better flow of the sequential LEDs) would it suffice to put a capacitor ( 1 uF capacitor or even a 4.7 uf capacitor) soldered into the Shunt Resistor?

 

So,.... if I want to DELAY the switching on/off of my turn signal (to allow a better flow of the sequential LEDs) would it suffice to put a capacitor ( 1 uF capacitor or even a 4.7 uf capacitor) soldered into the Shunt Resistor?

No, I don't think that would work. I'm not an electronics expert but I think you'd need to have an some sort of RC circuit (Resistor-Capacitor) connected to the relay coil to hold the relay on for a longer period of time. You'd want to charge the capacitor when power is applied to the relay coil then have the capacitor discharge via a resistor. That would hold the relay on until the voltage in the capacitor had dropped below the relay's release voltage. The problem is the capacitor would get charged again the next time power was applied to the relay coil by the micro processor, so the relay might never switch off causing the turn signals to just constantly illuminate.

 

Thanks for the reply. I am no expert either (not at all actually) and I thought the Shunt Resistor + Capacitor would do the RC circuit trick


So, on an LED array where a sweep pattern (think knight rider) is performed only when power is present the fact that the relay never switches off (while the turn leveler is set to pass power to the relay) would be beneficial as the sweep or "organized on /off" of the LEDs would replace the "blinking" function of the turn signal. (whether that's DOT legal or not is another story). In other words, if you have a flex circuit board with 10 LEDs that perform a sweep pattern from left to right every time power is present, then you only need to turn off the power (i.e. move turn leveler to neutral position) when you want to completely turn off the LED signal (i.e. cancel the turn signal or complete the turn) but the intermittence of power is no longer needed during activation of signal.


Now the question is what would happen to the other relay and BCP components (microchip, etc) if constant power is applied for some seconds, or even for a minute or two (i.e. waiting at traffic light to make a turn).


PS: Sorry in advance if what I just wrote makes no sense at all.

 

OK, I see what it is your wanting to do and it's a very simple thing to achieve. No electronics knowledge required at all.

Simply remove the turn signal relay and use a short link wire to bridge the "B" & "L" terminals on the relay socket. You'll now have a constant 12V sent to the lamps when you move the stalk switch or switch on the hazard lamps....simples!

 

Thankyou did it today on a 2009 Elantra Touring (I30 for eveyone else) and works great.

Sent from my LG-H873 using Tapatalk

 

Thankyou did it today on a 2009 Elantra Touring (I30 for eveyone else) and works great.

Happy to here the mod worked for you too.

 

And with some experimentation/calculation the value of the shunt resistor could be altered to get the voltage drop with the lower current draw of the LEDs to match what the bulbs drop. The microcontroller doesn't care as long as it sees the same voltage drop from the loss of an LED. There might be a market for a Hyundai/KIA LED flasher module.


Excellent analysis and write up, sir!

 

And with some experimentation/calculation the value of the shunt resistor could be altered to get the voltage drop with the lower current draw of the LEDs to match what the bulbs drop.

I don't think that would be difficult. A simple Ohms Law calculation should be all that's needed to work it out. Problem is there are so many different configurations of LED bulbs out there. You'd probably need to work it out for the particular bulbs you were intending to fit.

But who really cares about the bulb failure warning anyway? I mean most folk are happy just to fit a load resistor in parallel with their LED, which stops the hyper flash but also stops the bulb failure warning from working. It will warn you that your load resistor has failed but nothing will happen if the LED bulb fails.

 

Ok, this is a bit of an old thread but I think still relevant.
I need a little help.
So in my newer 2018 Sonata Sport, is it true that it may not have a separate flasher "relay"/controller? I looked under the dash but can't see any control relay to swap out with a CF-13 LED type.


I read the service manual and it makes no mention of the relay but it does state that the blinking rate is controlled by the CAN. It has to sense the current somewhere to double the normal rate of ~85/min to 170.
There is also a small speaker to make a nice clicking sound.


Adding load resistors is easy in the trunk but the front turn signals have the connection to the bulbs integral to the plastic housing which makes it non-trivial to add load resistors there.



Dave

 

Hi Dave.

I don't have any info for models as new as yours, but I doubt it will have a stand alone flasher unit. Even the previous generations of Santa Fe didn't have one. On those earlier models it was part of a relay module but I wouldn't be surprised if they have done away with the relay entirely by now. I've converted a few fully solid state flasher units though and they still measure the current flow in the same way as the old one I've shown above, using a shunt resistor. You probably wouldn't want to open your BCM and start cutting up the circuit board though. Not while the car is still under warranty anyway.

BTW, you don't need to connect the load resistors right at the front turn signal bulbs. You can connect them anywhere in the circuit. I assume your turn signals are integrated into the headlamps, so why not splice into the turn signal wire at the headlamp harness connector, or you could even attach them to the wire where it exits the dashboard fusebox.

 

It appears this module was designed out a few years back. As you said the computer controls the flashing now and I really don't want to cut into the PCB.


The headlamp harness connector assembly has 7 wires so now I have to get either a current or volt meter to zero in on the turn signal wires. Unless the service manual points out the wire and color?

There's a convenient area right behind the assembly to mount the resistors.

 

I’m having the same predicament as you. I had purchased some bulbs that had built in canbus error free sensors, but they ended up failing days after installing them. Is it true there is no resistors on the 2018 Sonatas?

 

The 6 or 8 ohm resistor in parallel with each turn signal LED worked well for me. They're brighter with no hyper-flash.



The resistors are designed to handle up to 25 watts but since the flash is a 50% duty cycle they should never get too hot if mounted to metal.

 

Well, after 3,000+ posts on the forums I thought it was about time I actually started a thread, so here goes :

I've come across a few threads recently were folk are fitting LED bulbs to their indicator lamps and having trouble with what is generally called hyper flashing lamps. The two common ways to combat hyper flashing is to either fit load resistors in parallel with the LED bulbs or replace the flasher relay with an LED compatible unit.

Today I was asked by a customer to fit load resistors to his flasher circuits because he had replaced the standard bulbs with LEDs and was suffering from hyper flash. The main benefit of fitting LED bulbs, to me at least, is they're much more energy efficient than the incandescent bulbs they're replacing so it seems daft to fit load resistors which makes the LEDs as inefficient as the original bulbs. So rather than fit load resistors I had a go at modifying the original flasher unit to make it LED compatible. This turned out to be a very easy mod and I've uploaded some photos below to show how to do it to a standard Hyundai flasher unit. I realize that stand alone flasher units are becoming rare but it wouldn't surprise me to find that the same basic circuit is used in the electronic control units on newer models. The micro processor used was designed specifically for automotive flasher units so the same chip might be inside the relay module on the Santa Fe, for example.

So, what causes hyper flash?
Well, inside the flasher relay there are 3 basic components : a low value shunt resistor, a micro processor, and the relay itself.

The shunt resistor is wired in series with the 12V supply to the relay, so the current that is being drawn by the flasher bulbs has to pass through this resistor. The voltage drop across the resistor is measured by the micro processor. The more current that passes through the resistor, the higher the voltage drop across the resistor will be. When a bulb blows the current drawn by the bulbs is reduced which in turn reduces the voltage drop across the shunt resistor. When the micro processor detects that the voltage drop has reduced below a specific value it switches the relay on and off at twice the normal rate to warn the driver that a bulb has failed. This is the same thing that happens when you replace your bulbs with LEDs. The current drawn by the LEDs and therefore the voltage drop across the shunt is too small and the processor gets stuck in "hyper flash" mode.

So, what's the fix?
It's easy really. All you need to do is prevent the micro processor from measuring the voltage drop across the shunt. All that involves is opening the relay and cutting the track on the circuit board inside that carries the voltage drop from the resistor to the micro processor. With the track cut the processor has no way to know that a bulb has blown (or you've replaced the bulbs with LEDs) and it maintains it's normal flash rate. The photos below show what track you need to cut.

I hope someone decides to fit LEDs to they're older car and finds this info useful.

Cheers.
Scottie.

Hello all! I'm VERY late on the draw here, but I'm wanting to upgrade my 2016 Hyundai Accent Sport to LEDs all around. From what I've read, I will likely encounter hyper flash when I install the turn sig's. I'm really not interested in fitting load resistors, so I was wondering if there is a way to apply the mod in the OP to the equipment on my car (the flasher relay does not look like the one in the OP; link to pic below). I think the part number for the flasher relay on my car is 952401r100, but I'm not sure. Any help would be much appreciated!

Redirect Notice

 

I was wondering if there is a way to apply the mod in the OP to the equipment on my car

Probably.
I've done this mod to quite a few different flasher relays. Even fully electronic ones that don't have a mechanical relay inside. The bulb failure circuit in them all works in basically the same way. It works by measuring the voltage drop across a shunt resistor. Disabling the voltage drop measurement circuit will disable the hyper flash.

I think the part number for the flasher relay on my car is 952401r100, but I'm not sure.

No, I don't think that is correct, given it says it's a stop signal relay on the packaging. According to Google the flasher relay will more likely be 95550-1R000

If I helped you fix it, why not...

Your support is greatly appreciated​

 

I have found that on small traces it is safer to make multiple shallow depth cuts with light pressure. Less chance of the blade going off target with force.

 

Hello again! I've made some progress in my quest, as you can see in the pics. Now that I have the flasher module out and taken apart, I need to figure out which track to cut. Unfortunately, I have no idea what I'm looking at! 😅 Could somebody please circle/highlight the track I need to cut to kill my hyperflash? Thanks in advance!

 

UPDATE!

I've killed my hyperflash! The modification was actually quite simple. All I had to do was remove the "sense" pin resistor from the pcb inside the module, and the LED bulbs flash at a normal rate (see image; the arrow is pointing at the resistor to be removed). It even still flashes three times when I tap the stick (usually when changing lanes) - very nice!

A huge thanks and shout out to Autospark who walked me through this mod every step of the way - I never could've done something like this without lots of help and guidance, and Autospark's input was invaluable!

 

A huge thanks and shout out to Autospark who walked me through this mod every step of the way

Great to hear it worked. I can go lie down in a dark room now and allow my head to recover from having to decipher all the gobbledygook in the datasheet for that chip

If I helped you fix it, why not...

Your support is greatly appreciated​

 

For future reference, an old technicians trick when removing a small discrete surface mount component that "might" need later reinstallation is to use a technique called tombstoning. Unsolder the part, then stand it on end and solder it to just one of the pads. That way, if for whatever reason, you need to reinstall the part you have it right there on the board. Good technique for all things electronic, not just flasher mods.

Great job, Mr. Robson! Count yourself as one of many who have found answers from AutoSpark!

 

So I know this thread is pretty old, but I have a 2013 elantra limited with a smart junction box that controls a lot of functions, including flasher speed. Does anyone have experience modifiying one of those to eliminate hyperflash?

 

I think you should just fit load resistors in parallel with the turn signal bulbs on your 2013 Elantra. The lighting circuits on later model cars are controlled by an electronic circuit called IPS (Intelligent Power Switch). I doubt it would be an easy task to modify that.

 

Thanks for the fast response, I was hoping to avoid that because of power draw but honestly it's really not that big of a deal. I'll buy the load resistors and install them. I think I may be able to get away with just doing the fronts because even with the LEDs, the 4 way flashers go at a normal speed

 

Sorry to resurrect an old thread, but this is good info! Check your pm plz I have a question

 

I finally got around to installing 2 of the load resistors a couple days ago and I'm happy to say that I only needed 2 in order to kill the hyperflash. I installed them on the front, in parallel from the blinker power to ground. Left headlight is a blue wire with red stripe, the right headlamp is an orange wire with red stripe. I used a posi-tap with electrical grease to percent corrosion, and then I wiped off the extra grease and painted it with liquid electrical tape to ensure a weathertite connection. If my math is right, it'll only be a couple amps running thru the tap and resistor so that set up should be perfectly fine.

 

@Finer.Automotive.... Did you connect the Load Resistor to the ground on the headlight harness or direct to ground on the vehicle?

 

Didn't mean to double post, it was giving me problems because I hadn't signed in for so long