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I was wondering, would anyone be interested in a tutorial/write up on how to fix hyperflashing when changing to LED turn signals?
I personally did this on my 2005 Ford Expedition EB, where I initially planned to used an electronic LED flasher like the commonly available EP27, but when installing it I really hated that relay. It was flashing too fast, the ticking had an annoyingly thin sound and it gave 2-3 ticks after turning off the turn signal. I might have more OCD than others, but I royally hated that relay.
I ventured on to modify the stock OEM Ford flasher to work with LED lights, which was a very easy thing to do. If there's any interest in how to do this, I can take it out from the truck and shoot some pictures of the mod and explain the basics around it so those who are interested can do this as well. I'll also provide info on the LED bulbs I used.
You might've gotten a bad EP27 relay ? I got one from SuperBrightLED and it's been normal cycle click and 100% reliable since installed about 8 years ago. Where did you get yours? Or what brand was it if you know? The Novita EP27 that they sell at Advance Auto now is shorter and fits under the dust cover, and it's made in the USA.
Got mine off ebay, looks identical. It worked, it's just that I didn't like the way it works. The flashing rate was too fast, not hyperflashing, just a bit faster than normal flashing. The sound of the relay is very subjective I guess, but the ticking of the OEM is more like a large clock, while the ticking of the EP27 is more like a small PCB relay, which is exactly what it is.. hehe. It just bothered me, but as I said, that part is subjective. The most annoying part was that when I turned off the flasher, it would give 1, 2 or sometimes 3 ticks after it was off. Not sure why, but didn't like that. The lights wouldn't flash so it was fine, just annoying.
But basically you don't really need this relay at all. The OEM Ford relay works fine with LED, all you have to do is modify the shunt resistor inside it to account for a smaller load, which is what it uses to figure out when to hyperflash when a bulb burns out. The bonus is that if ever an LED bulb for some reason stops working, it will hyperflash and let you know. As far as I know, the EP27 will not hyperflash.
A second bonus is that the cover over that relay box will fit as well, as the EP27 is somewhat taller and doesn't allow you to put the cover back on...
you just need a load resistor to compensate for LED low current consumption. The flasher circuit detects a low current flow and flashes rapidly (as if the bulb is busted or open)
Load resistors are a bandaid solution, not a real solution.
Ok, I'll rip the relay out of my truck again and shoot some pictures of it later today. I'll make a new thread for it I guess, makes it cleaner for a writeup.
When I installed LEDs in my van I just switched the flasher to an LED compatible one. I figured the resistor solution wasn't going to reduce any electrical load, so if I was going to go that route then why bother switching over to LEDs in the first place.
The load resistor is useful when your relay is handling other non-led bulbs. There are cases where you can't change all the lights to led and have to leave the rest to just plain bulbs, in this case if you use an LED flasher there's no indicator when those bulbs are busted/open.
So not really a band-aid but a work-around.. it;'s been discussed in other auto forums I joined in...
Ok, so here's the writeup on how to properly fix hyperflashing. This will work regardless if all turn signal lights has been replaced with LEDs or if you're running a mixed setup with some incandescent and some LEDs.
The best thing is, this is basically free to do, no need to buy a new relay, no extra parts needed. If you have some piece of wire and a basic soldering iron, you're good to go.
So, when you replace your turn signal lights with LED bulbs, you'll notice that they're flashing rapidly as if a bulb has burnt out, this is hyperflashing. This is caused by the decreased load which the LED bulbs represent. There are multiple ways to fix this.
The bandaid approach is to hack in a load resistor, which is a less elegant solution. It has to be mounted to metal, and you modify the wiring in a location where it is exposed to the elements. It generates heat, and basically removes one of the positive points of using LEDs, lower load on circuitry and so on. In US cars, the rear turn signal bulbs are the same as the brake lights, which is used a lot and will generate more heat. Not a good solution, and I'd recommend avoiding this as much as possible.
The standard approach is to use an electronic flasher relay. This is a great solution. It's easy and doesn't modify anything in the vehicle. Swap out the relay, and you're good to go. But, they may have different flashing rates, which may be annoying. And they will never hyperflash to warn you if a turn signal is out. Lastly they may have a different size so they don't fit in with the cover on the relay box or whichever location it's mounted. In Expedition, this is behind the lower dash above the drivers knees, and it has a cover over it. Personally I didn't like this relay at all, but your mileage may vary.
The most elegant approach in my opinion is to simply modify the stock OEM flasher relay to work with LED bulbs. The positive in this is that you'll still get hyperflashing if a bulb stops working, and you still have the same sound and flashing rate on the turn signals, which I was very happy with. I'll show how to modify it here with some pictures, then I'll explain how and why this is working after for those who may be interested in this.
1. Get your flasher relay from the truck.
Here it is next to an electronic LED flasher relay, the EP27. Notice the EP27 is a bit taller, which won't allow the cover on the relay box to fit over it.
Open the Ford OEM flasher relay, it looks like this inside. Notice the shunt resistor, it's the metal loop in the red circle. Found this picture on Google from a website called "v-ledsblog.com"
Basically, you need to change the resistance value of this shunt resistor. Since the load of LEDs are smaller, you need to increase the resistance in this shunt resistor. There are two ways to do this. Either you can remove some of the material from it, making it thinner. Or you can replace it with something with higher resistance. I found it to be easier to replace it, which makes it reversible as well.
Here's my modified flasher relay next to the electronic one. I replaced the shunt resistor with a piece of wire of non-scientific length and thickness. It's a 0.3 mm2 or 28 awg wire which I cut to a practical length which would fit inside. This is all it takes to make the original stock OEM relay work with LED bulbs. You can do this with internal flashers which are integrated in modules as well, these are normally not possible to use with LEDs, but that can now be done if you're willing to take a soldering iron to it.
A couple of more pictures showing the wire placement.
Here you can see the shunt resistor where it used to be, and the wire I soldered in.
So, why does this work?
A flasher relay uses a shunt resistor to measure the current drawn by the turn signal bulbs. When a bulb burns out, the current drawn by the circuit is reduced and the relay starts hyperflashing. The shunt resistor is tuned to the number of bulbs in the turn signal circuit. Look at the gif below to see how this works:
So when we change the resistor, we basically "adjust" the setpoint for which the flasher relay will hyperflash or not. This can be tuned very accurately if you wish, by starting with a big wire, then step down to a thinner and thinner wire until the flasher is flashing steady and not hyperflashing, or you can basically eyeball it with a wire which you know is thick enough to handle the max current draw of the circuit. To find the current draw, take the bulb rating (i.e. 10W) and divide with voltage (12V) and you get 0.83A. If you have 4 bulbs of 10W each, it's 40W and max current of 3.33A when all are on.
For Expedition, the turn signal bulbs are 3157 and if you have turn signals in the mirrors use 3156.
Ok, so here's the writeup on how to properly fix hyperflashing. This will work regardless if all turn signal lights has been replaced with LEDs or if you're running a mixed setup with some incandescent and some LEDs.
Okay, wanted to give you rep points over that DIY write-up, but the system won't let me. Must've given you some elsewhere recently.
Excellent write up. Thank you for doing it with pics. I chose to just trim the shunt resistor down with a dremel tool. I chose to cut down the easiest part, the double bumps, rather than the harder to get to inside bump. Worked like a charm. Thanks
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