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Fixing hyper blink LED turn signals without load resistors

55K views 16 replies 11 participants last post by  Dek Ngo 
#1 · (Edited)
I replaced the front turn signal bulbs with LED bulbs and saw the dreaded hyper blink. I had my load resistors ready (to draw the same amount of current as the stock bulbs), but it seemed like a horribly brute force way of doing things. A little searching on the web brought me to people that disabled the hyper blink feature of the stock relay ( http://www.yotatech.com/f2/cheap-bastards-idiot-guide-fixing-fast-blinkers-after-led-swap-80626/ ). I took that one step further by keeping the bulb failure sense in place by modifying the relay circuit. You need to be able to solder for this mod.

Why?:
The stock turn signal relay has an integrated circuit inside with the relay. The IC looks at the turn signal current flow. When you left turn signal is on, the current of both the front and back left turn signal flow through the relay. If the current is a lot less than it should be, then it assumes a bulb burned out and flashes the good bulb very fast. When you use LED bulbs, the current is low and the circuit thinks there is a problem.

1 Take apart the dash just below the steering wheel. Steps 6 - 8 of this tech article show how to do it http://www.customtacos.com/tech/index.php?article=77

2 You now can see the fuse box under the dash near the driver's side door. The turn signal relay is on the back side of the beige fuse box.



It is up near the top of the fuse box (back side). Here is the view you get with your head down by the brake pedal. You can remove the fuse box or just reach up there and grab it. I left the box in place. The arrow points to the relay.



3 Pop the cover off the relay by pushing in on the tabs. There is that IC that causes the hyper flash.



The turn signal current flows through a resistor causing a very small voltage drop that the IC can read. The resistor is about 30 milliohms. The red tool is resting on the resistor (basically a a wide piece of metal).



4 You need to change the value of the resistor so it doesn't go into the hyper blink mode. The resistance needs to go higher. There are two ways to do this. You can buy a resistor from places like Mouser, Digikey, or possibly Frys or you can modify the stock resistor. I took the Dremel and started making the stock resistor more narrow. That increases its resistance. I had it right about where it needed to be when the Dremel tool threw it. I never did find it. I wound up using some resistors I had laying around (three in series to get what I needed). Shaving the stock resistor down is probably the easiest, but measuring the value as you go is a problem since most volt/ohm meters can't measure that low with any accuracy. Here are my three surface mount resistor I used soldered in series and in place. A single through hole resistor would be ideal.




Choosing your resistor value:
You could just shave/trim the stock resistor and keep checking to see if your hyper blink goes away. You should unsolder the stock resistor to either shave it or replace it.

The stock relay is setup for incandescent bulbs. The front and back set (left set or right set) draw about 4A total (2A per bulb). If one bulb dies then you only have 2A. They put the hyper flash trip point near 3A (high enough you won't get false triggers, but low enough to catch a bad bulb). When less than that current flows the voltage drop across the resistor falls below the fixed 80mV trip point for the IC (80mV is set inside the IC).
For example, lets say you are using front and rear LED bulbs for turn signals. These bulbs draw about 1/2A each for 1A total. You want the trip point to be above 1 bulb, but below 2 bulbs so pick 0.75A. Now a little ohms law. (0.75A X resistor value) = 80mV. 0.75A / 0.08 = 0.11 ohms. Call it 100 milliohms. Replace the resistor with 100 milliohms and you should be set. Use a resistor rated at 1/4 Watt or higher. Higher rated power resistors are best as long as they fit inside the relay case.

Matt
 

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#5 · (Edited)
The V-LED Switchbacks? Yep, those are the ones I did this mod for. I'll post about the switchback LEDs later this week. I need to get a new turn signal housing before I take pictures/video. I noticed the passenger side housing is missing most of the reflective coating inside. I wondered why the driver side LEDs looked so much brighter.

what would the cons be to just clamping on a load resister? any chance your selling modded versions?
Load resistors aren't exactly Satan. You do have to install two of them and when your turn signals are on they are throwing away all that power. Not a big deal. I'll spend days at work trying to increase the efficiency of a power supply by a few percent so it was just hard for me to save all that power with LEDs and then throw it away in resistors that do nothing. Oh... and of course you keep your burned out bulb sensing with this mod. The hyper blink will still work if you lose a bulb.

The data sheet for the IC in the turn signal relay is here http://www.n6eaj.com/Tacoma/Atmel_flasher_doc4727.pdf

Matt
 
#7 ·
thanks for this, had a hard time finding the relay location, even tougher time feeling around to put a new one in. Had to take a cell phone pic of it so i knew what i was feeling but the relay i got works. (superbrightleds dot com) . New tailights installed!
 
#11 ·
The resistor sets the threshold of what is considered too little current and is required as all of the blinker current passes through it (no resistor, no current flow, no turn signals). You normally have the current of the two bulbs going through the resistor. That creates a certain voltage drop. When one or both of your bulbs burn out, the current goes down and so does the voltage drop. Too low of a drop (not as much current flowing) and the flasher knows there is a problem so it does the hyper blink to let you know. When you replace your incandescent bulbs with LEDs, there is a lot less current flow and the dreaded hyper blink. These days I believe you can just buy a relay for our trucks that plugs in that is "LED ready".
 
#14 ·
2013 Tundra - Hyper flash. Newbie posting. Everything will not be organized, bear with me. 2013 Tundra front signal, park, driving lights factory bulb gets too hot. Starts to melt bulb holder. Changed to led bulb, which was hard to find for this vehicle. Got hyper flash. Had to take apart dash above parking brake. Turned on blinkers, found 18 pin flasher module. There are 2 resistors, RS1 & RS2. RS1 is for the left side of the truck and RS2 is for the right side. Bend RS1 to the side and grind off approx. 1/3 off of metal horseshoe shaped resistor R2. Plug it back in and test it. When you get enough off it will blink normally. When you get it right, bend RS1 back into place, carefully, and do the same for it. I have pictures of all this but don't know how to attach them, sorry. Any questions are welcome because I did this the HARD way and ended up at the dealership to clear all kind of false codes. Hope this helps somebody. DAD
 
#16 ·
The part number for your 2004 2RZ 5-lugger's flasher unit should be:

81980-AC030

The most likely Toyota LED flasher on the Autolumination page (top row; right end) shows part number:

81980-22070

According to the parts listings at ToyotaPartsDeal, PN 81980-22070 will NOT fit a 2004 2RZ 5-lugger.

That's all I can tell based on the sketchy descriptions ...
 
#17 ·
I know this is an old thread, but I just wanted to add some info to help out with the OP's mod.


I've been using a replacement relay from SuperBrightLEDs for several years and it has worked well to fix the hyper blinking. It always bothered me that it clicks 2-3 extra times after the signal is canceled, though.


I'm renovating my truck and wanted to go with the OP's mod to my original flasher relay, but rather than grinding the "resistor loop" and guessing on its resistance, I bought a 100mOhm 1W resistor from Mouser Electronics (Ohmite - WLBR100FET - Through Hole Current Sense Resistor), removed the "loop" and replaced it with the resistor. This requires only rudimentary soldering skills and it works perfectly.
 
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