LED turn signals? Mod your flashers the RIGHT WAY
 

Hey guys -

So I've started down the wacky fun path of going mostly LED lighting on my car. One of the primary reasons is the FD's external light circuit is somewhat underbuilt, anyone who has seen their dash lights dim at a stoplight with your foot on the brakes knows what I mean.

So, I went all LED taillights with bulbs from CTLumination. They work GREAT, very pleased, no more dim lights. So, next on to the turn signals.

If you replace the stock turn signal bulbs with LED's, the turn signals will flash too fast. The solution has been to wire in resistors to the turn signals to fix it.

THIS IS A POOR SOLUTION.

You have these nice, low current use LED's and you're wiring in resistors - their only purpose is to create load and turn electricity to heat. So, you add more heat and more load into the equation. The LED's end up using the same current draw if not more, and you have a resistor pack that can fail on you (other car forums have had problems with resistor packs, BTW).

So, what to do?

The FD has the turn signal flasher module in the CPU #2. This is the black plastic box behind the driver's kick panel, it's in the bottom of it.

The design of the flasher takes into account if you have a burned out bulb. If you do, it will flash quick (due to lower load on the circuit) so you'll know and change your bulb. When you put in LED's, their load is so low the flasher circuit thinks there's a bad bulb.

Guess what? LED's last THOUSANDS of hours longer than incandescent bulbs, so them burning out prematurely is far less of a problem. And, I'm going to assume you're a big boy and can keep an eye on the status of your bulbs - hell, the FD doesn't tell you if you have a burned out brake light, you have to check the bulbs yourselves.

So, what this mod does is disable that "your bulb is bad" circuit in the flasher and your turn signals flash nice and regular.

Head to Radio Shack, pick up a pack of 1 megaohm resistors, part number 271-1134. They're 99 cents for a pack, my crappy Radio Shack had them in stock after I walked past the cell phones and RC cars.

Pull the CPU out, remove the screw and the bottom, and use a thin blade to pop off the plastic cover on the bottom. The flasher module will slide right out.

On the left hand side is a resistor marked R1. Desolder it and remove it from the board. Solder in the 1 megaohm resistor in its place, plug it in and test, you should have nice, regular flashers.

Just did this on my car, fortunately I used to own an FC and can solder/desolder Mazda electronic parts in my sleep :).

Enjoy!

Dale

Nice! Bookmarked.

Nice!

Thanks for the neat write up!

Steve

Nice, I was looking at doing something like this myself. Good write up!

Great help!

Thanks.

Dale probably just created a run on CPU #2's. Haha. Who will give me ONE MILLION DOLLARS for my extra CPU #2? =)

:icon_tup: As someone who's electrical knowledge ends with putting a plug into a wall socket, I marvel at how you guys figure this crap out.

Hahaha +1

Haha!

BTW, some of the other stuff I've read on other car forums when searching for LED info leads me to believe that the resistors are really a bad way to go. Jeep and truck guys have been doing LED tails for ages, they complain that if the resistors are near plastic it will melt it, some have had wiring melt from the heat, etc. This is not the way to go, especially when a simple fix can remedy the problem.

I'd be mortified if I discovered any melted plastic or burnt wiring on my car from a mod I did!

If any of you guys lack the soldering skills PM me, I might be able to help ya out!

Dale

So this wouldn't cause any issues if you were to switch back to regular bulbs afterward? You just wouldn't get the warning if a bulb burned out?

Correct, it just disables the warning mechanism. Not to mention I doubt you'd want to go back after seeing the LED goodness :).

Dale

Wow, I wonder if this will work on my Yamaha R6, as well. The R6 community just shows how to use the resistor.

Nice

Added to FAQ thread

What soldering setup do you use? (solder type, iron type etc). I've had some crappy ones for a while and they don't seem to cut it. But maybe that's just because I've got no skills.

+1 seriously...who sits there and figures shit like this out...f'in genius.

I have a VERY low tech soldering setup. A basic soldering iron, a solder sucker, and some desoldering braid was all I used. That and some good quality solder for the new part.

Hardest part is just removing/desoldering the old resistor, the rest is cake.

On the Yamaha, take a look at how the system is set up. Most cars use some sort of flasher relay, most are 3-wire relays (Mazda had to go complicated for some reason). If so, they have replacement LED-friendly relays.

I tried to find a replacement that would work to no dice. Modding the existing one is the way to go - plugs in, works great, nice and clean, no hacking wiring or anything. And not expensive to do.

Dale

Just curious what model LED bulbs from CTLumination you ended up using for your brake/signal lights and how well do they light up the housings? Do you have any pictures?

Dale - Thanks for the great write up. As always well documented and correct. I just did this mod to my flasher after coverting over to LEDs and reading your thread. It was very simple to do.

If the resistor is melting plastic then the resistor has to be way past it's wattage rating, right? If the lights are getting 12v I really have to wonder how many amps they're pulling in order to make a resistor melt plastic.

Regardless, it's silly to waste electricity to make a resistor hot. Not to mention wiring in all the resistors to do the job is probably MORE work than modifying the CPU and doing it right in the first place.

I don't know of any resistor related meltings on an RX-7, I'm just reporting what I've seen from Googling around on the topic. It's a common problem for guys with other vehicles. And, again, why hack up your wiring and buy a bunch of pricey, hot resistors when a simple fix with a soldering iron does EVERYTHING for a few bucks AND it works right?

Dale

+1 ^

I plan on doing this mod eventually so I can install the blinker led's I have laying around.

Can you give a quick "how to" on using Desoldering Braid?

Yay links.
Thank ya sir.