MOTOBRICK.COM

TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: frankenduck on June 18, 2011, 01:21:49 PM

Title: DIY LED flasher relay
Post by: frankenduck on June 18, 2011, 01:21:49 PM
The factory flasher relay doesn't like LEDs.  I decided to build my own.

What's needed:

Two PCB(printed circuit board) 12V latching relays: http://www.futurlec.com/Relays/LATCHREL12V.shtml (http://www.futurlec.com/Relays/LATCHREL12V.shtml)

Five 12V diodes from radio shack: http://www.radioshack.com/product/index.jsp?productId=2049725 (http://www.radioshack.com/product/index.jsp?productId=2049725)

One 12V DPDT PCB relay (generic item) so you can turn the hazards on while the bike is turned on but not while it's off. (Similar to how the factory flasher relay works.)

Toyota LED flasher relay: CF18-08

Here's the wiring diagram:

(http://i236.photobucket.com/albums/ff192/owrstrich/MB%20dot%20COM/LED_flasher_relay_rev2_zpsa0e436cb.jpg)

(http://i236.photobucket.com/albums/ff192/owrstrich/flasher_relay_pinout_zps8552243c.jpg)

Here's the finished product.  I made it small enough so that I could solder it into an OEM flasher relay housing so it's plug-n-play.  The only function it doesn't have that the OEM one does is auto-cancel but I never liked that anyway.

(http://i236.photobucket.com/albums/ff192/owrstrich/IMG_1669_zps665e9645.jpg)

(http://i236.photobucket.com/albums/ff192/owrstrich/IMG_1665_zps02ceebc1.jpg)

(http://i236.photobucket.com/albums/ff192/owrstrich/IMG_1663_zps27d073b9.jpg)

It's been in my K1100RS and working fine for over two years.
Title: Re: DIY LED flasher relay
Post by: CubPilot on June 18, 2011, 02:55:41 PM
Dammit Professor, something else I have just got to try!!!!
Title: Re: DIY LED flasher relay
Post by: DirtyF on June 28, 2013, 10:49:17 AM
Hello from France  :riding:

This is the only place where I found this information  :2thumbup:

Unfortunately the pictures are gone, is it possible to put them back ?

Thanks in advance.

Best regards,
Francis.
Title: Re: DIY LED flasher relay
Post by: bikerboy on July 06, 2013, 04:11:17 PM
Hello from France too. No need to go to great lengths, just open the existing relay and cut pin 7 to the chip in it. Works fine on mine and I have LED indicators front and back now.
Title: Re: DIY LED flasher relay
Post by: TimTyler on September 19, 2013, 12:15:57 PM
Updated with images...
Title: Re: DIY LED flasher relay
Post by: TimTyler on September 19, 2013, 12:20:54 PM
Is there a problem letting LED turn signals hyperflash which is what happens without a load resistor installed?
Title: Re: DIY LED flasher relay
Post by: rbm on September 19, 2013, 12:56:33 PM
Technically, probably not.  Socially, it will probably attract the attention of the cops, who will assume a burnt out bulb and pull you over for inspection.  Almost certain if this happens in Toronto, they'll find other stuff to issue a ticket.  I believe Europe has an SAE standard for blick rates to be between 60-120 flashes per minute.
Title: Re: DIY LED flasher relay
Post by: bikerboy on October 26, 2013, 12:07:46 PM
As I said earlier, one little clip with a pair of side cutters and you can fit LEDs into all or any of the flashers and they will flash at the correct rate. Why would anyone go and build stuff to achieve the same result?
Title: Re: DIY LED flasher relay
Post by: johnny on October 26, 2013, 12:11:13 PM
i have not tried bikerboys suggestion... butts after reading ohms law... thats the way i would do it...

j o
Title: Re: DIY LED flasher relay
Post by: bikerboy on October 26, 2013, 02:46:36 PM
I have tried it and it has worked fine on my bike for 8 months and 10,000 miles.
Title: Re: DIY LED flasher relay
Post by: Doc_69 on November 24, 2014, 02:58:51 PM
I have tried it and it has worked fine on my bike for 8 months and 10,000 miles.

Apologies if I'm being a bit thick here, but could you please explain this in a bit more detail. I am trying to convert everything that glows to LED. Ali I'm getting at the moment is a whole lot of buzzing.

Thanks

Jason
Title: Re: DIY LED flasher relay
Post by: Inge K. on November 24, 2014, 03:42:52 PM
Cut the connection to the leg beside the red dot:

Title: Re: DIY LED flasher relay
Post by: Andrewck on April 19, 2015, 12:09:10 PM
Doc_69 how did this work for you?  I'm thinking about making the cut.  I believe bikerboy when he says he's had no issue with it, but it would be nice to have one more verification that this works before I go and muck up my bike even more.
Title: Re: DIY LED flasher relay
Post by: Scott_ on April 19, 2015, 12:27:08 PM
Doc_69 how did this work for you?  I'm thinking about making the cut.  I believe bikerboy when he says he's had no issue with it, but it would be nice to have one more verification that this works before I go and muck up my bike even more.

If you want one to experiment with.
http://www.ebay.com/itm/Oem-Bmw-Nos-Flasher-Relay-Part-61311459224-/271842606623?hash=item3f4b14fe1f&vxp=mtr

$20 so far.
Title: Re: DIY LED flasher relay
Post by: Andrewck on April 19, 2015, 01:10:24 PM
Just pulled out my flasher relay to cut beside the red dot.  Is there a secret to opening up the flasher relay?  Mine is sealed pretty securely.  Also what is the best way to reseal it after I make the cut??

Also confused as when you look at the outside of the relay there are pins numbered 1-8 on one row and 9-15 on the top row.

Is it meant to open the relay and cut next to the red dot or keep the relay sealed and cut the pin that says '7'??  Thanks so much
Title: Re: DIY LED flasher relay
Post by: enb54 on April 19, 2015, 01:35:57 PM
Doc_69 how did this work for you?  I'm thinking about making the cut.  I believe bikerboy when he says he's had no issue with it, but it would be nice to have one more verification that this works before I go and muck up my bike even more.

If you want one to experiment with.
http://www.ebay.com/itm/Oem-Bmw-Nos-Flasher-Relay-Part-61311459224-/271842606623?hash=item3f4b14fe1f&vxp=mtr

$20 so far.

More information is at http://www.triumphrat.net/maintenance-and-workshop-talk/213347-led-turn-signals.html and the flasher unit IC is a U243B (original looks like from Telefunken) which apparently is fairly common. You should be able to open up the relay by prying apart the plastic case at the connector edges, mine is maybe the old style, you may have to cut yours apart. Reseal with silicone sealant to keep out weather and insects...

That would be pin 7 on the integrated circuit U243B, not on the relay plug...
Title: Re: DIY LED flasher relay
Post by: Andrewck on April 19, 2015, 03:06:50 PM
Thanks for the links.  My problem is trying to get the relay box open.  Don't seem to be any tabs or way to open the relay box easily or without brute force.  Off we go...
Title: Re: DIY LED flasher relay
Post by: Andrewck on April 19, 2015, 03:22:36 PM
OK, got the cover off and now I'm staring at the below.  Doesn't look like the relay that was posted previously.  What do I cut??
Title: Re: DIY LED flasher relay
Post by: Inge K. on April 19, 2015, 04:26:36 PM
Another red dot.
Title: Re: DIY LED flasher relay
Post by: Andrewck on April 19, 2015, 05:45:56 PM
Blink Blink Blink

It's alive!  Thank you so much!!  Best mod ever.
Title: Re: DIY LED flasher relay
Post by: rbm on April 19, 2015, 06:19:48 PM
(https://lh3.googleusercontent.com/-YzynzvfsrI8/VTQpHDPmRiI/AAAAAAAAEb0/l6uga-aBOOo/s800/flasher.png)

I would recommend cutting the trace indicated by the yellow arrow (above), rather than clipping the lead from the IC.  This cut ends up with the same result, but is reversible should you wish to return the relay to stock.  If you clip the IC lead, the operation is not reversible.
Title: Re: DIY LED flasher relay
Post by: ts888 on July 25, 2015, 12:38:26 AM
Cut the connection to the leg beside the red dot:

I just performed this magic tonight.  Works a treat!  The simple way is to flip the relay over and cut the trace on the back of the board, much more convenient than getting in the tight space to cut the leg off the chip.  And if you ever want to reverse the mod, you can solder the trace back easily.
Title: Re: DIY LED flasher relay
Post by: Party Cat on July 29, 2015, 10:26:07 PM
Just put indictaors with LEDs on my 91 K100LT and when I put on the indicators they light but just stay on (no flash) and get a whining noise from the relay.  Will the fix mentioned previously in this thread alleviate this issue?  Thanks!
Title: Re: DIY LED flasher relay
Post by: Party Cat on July 30, 2015, 06:56:31 AM
To answer my own question yes that worked!
Title: Re: DIY LED flasher relay
Post by: Party Cat on August 12, 2015, 09:07:35 PM
One more follow up:

I'm not sure yet 100% if it's related to the modification to the board I did to get the flashers to work with LED but I'm having an issue where the indicators and horn stop working.  I checked the fuses and switched the 15 horn fuse with the 15 indicator fuse and then they started working.  Next day back to not working.  Switch the fuse and working again...I found if I give the fuse a wiggle it comes and goes so fuse connection is funny...

Edit - was a hairline fracture in the 15 fuse  :dunno
Title: Re: DIY LED flasher relay
Post by: rbm on August 12, 2015, 11:52:08 PM
It's not uncommon for these fuse types to go bad internally with no outward signs, just as you experienced.  It's always a good idea to continuity check the fuse as part of your diagnosis.
Title: Re: DIY LED flasher relay
Post by: Party Cat on August 12, 2015, 11:53:30 PM
Thanks mate!

Just added backups and backups to my under seat box ;)
Title: Re: DIY LED flasher relay
Post by: Motorhobo on August 19, 2015, 09:23:36 PM
Another +1 for cutting the trace as described above. I'm running a sidecar on a K75 and I replaced the original incandescent cans on the hack with beehive LEDs. That means I had to remove the bulbs from the right  hand front and rear signals on the bike because they're replaced by the sidecar lights. Hyperflashing ensued.  I tried using a load resistor but the thing got so freaking hot it scared me and I couldn't find a place to mount it because it's clunky and heavy besides being hot.

Getting the relay box open is a challenge as mentioned above. You have to cut though the rubber insulation on the bottom end and gently pry it open at the narrow ends which is where it clamps in. Afterwards I sealed it back up with RTV. Now I can think about replacing all the signals with LED bulbs -- awesome mod!
Title: Re: DIY LED flasher relay
Post by: ChristSFP on August 24, 2015, 02:12:25 PM
Would this also work on a K1100RS?
Title: Re: DIY LED flasher relay
Post by: rbm on August 24, 2015, 05:21:31 PM
Yes, it should.
Title: Re: DIY LED flasher relay
Post by: ChristSFP on August 25, 2015, 03:03:35 AM
Thanks for the quick reply!

Sorry, but just be clear:

IF I cut the cord according to the thread info, I would not need to use resistors when installing LED turn signals? (Rear turn signals will have integrated break light also, but I guess that won't be effected by this operation either?)
Title: Re: DIY LED flasher relay
Post by: rbm on August 25, 2015, 05:59:27 PM
Yes, that is correct.  I would suggest slicing through the copper trace on the printed circuit board rather than snipping off the pin from the IC.  The slice can be reversed and put back to stock.  There should be no need for balast resistors to get the flashers working properly after doing this mod.
Title: Re: DIY LED flasher relay
Post by: ChristSFP on August 26, 2015, 05:15:40 AM
Thank you for your reply =) Saved me $30 on the build
Title: Re: DIY LED flasher relay
Post by: ChristSFP on August 27, 2015, 02:16:43 AM
Ok, so the mod solved my turn signals, however I can't seem to get the break light to work. Rear running light works..

So the rear turn signals has integrated break and turn signals and according to the diagram.. it should work =/

And tips?

Title: Re: DIY LED flasher relay
Post by: rbm on August 27, 2015, 10:42:27 PM
Your brake light problem is related to the Bulb Monitoring Unit (BMU).  The BMU needs to measure the current drawn by a standard incandescent lamp to work properly.  Your LED brake light is simulating a failed brake light bulb.  You'll need to add a ballast resistor in parallel to cause that needed current draw in the circuit and allow the BMU to work.  Alternatively, you can search this site to find out how to bypass the BMU.
Title: Re: DIY LED flasher relay
Post by: K75RT Keith on December 12, 2015, 09:48:41 AM
Cut the connection to the leg beside the red dot:

Inge K,  is there enough space on the back side of the board to cut through the trace?
Title: Re: DIY LED flasher relay
Post by: rbm on December 12, 2015, 03:04:41 PM
Inge's suggestion is to cut through the IC leg.  My suggestion is to cut through the trace on the back.  Yes, there is sufficient room.  If you examine with a magnifying glass, you'll see a small short trace leading to a large ground pad.  That's what you cut.
Title: Re: DIY LED flasher relay
Post by: K75RT Keith on December 12, 2015, 03:28:16 PM
Any recommendations for what use to cut the trace?
Title: Re: DIY LED flasher relay
Post by: rbm on December 12, 2015, 03:32:45 PM
A utility knife with a sharp blade or an Xacto knife with a sharp blade.  You just have to sever the continuity on the trace and it's very thin copper.
Title: Re: DIY LED flasher relay
Post by: Inge K. on December 12, 2015, 04:01:42 PM
Inge's suggestion is to cut through the IC leg.

Thank you for the correction..............I've always thought that cutting the connection to the leg was
different from cutting through the leg.
Title: Re: DIY LED flasher relay
Post by: rbm on December 12, 2015, 08:02:46 PM
Actually you have understood the subtle English language nuance correctly Inge.  Cutting the connection to the IC can be accomplished either by cutting through the leg of the IC on the top side of the card or cutting through the trace on the bottom side of the card.  They both end up with the same result.
Title: Re: DIY LED flasher relay
Post by: The Mighty Gryphon on December 13, 2015, 01:00:18 AM
I have found through considerable personal experience on a wide range of electronic equipment that cutting the trace is more easily reversible than cutting a component lead.  I learned this by frequently cutting the wrong thing the first time nearly every time.
Title: Re: DIY LED flasher relay
Post by: Nantucket_Red on April 13, 2016, 04:39:16 PM
I cut the trace and only get a solid light, did I screw up?
87 k100rt
Title: Re: DIY LED flasher relay
Post by: Nantucket_Red on April 13, 2016, 05:05:20 PM
I'm assuming it's because I didn't have my rear led lights wired. If when I wire them up and it doesn't solve the issue I shall assume I fudged up
Title: Re: DIY LED flasher relay
Post by: Laitch on April 13, 2016, 05:26:51 PM
I cut the trace and only get a solid light, did I screw up?
Post a picture of the trace you cut, Red. This is the time a photo would really clarify what you've done.

I'm assuming it's because I didn't have my rear led lights wired. If when I wire them up and it doesn't solve the issue I shall assume I fudged up
My suggestion is not to get ahead of yourself but to do one task at at time.
Title: Re: DIY LED flasher relay
Post by: Nantucket_Red on April 13, 2016, 05:33:50 PM
Soon as I can get back into the garage I shall. I was very careful when locating and slicing the tracer. I'm 99.9% sure it was the right one. But I will post a photo ASAP
Title: Re: DIY LED flasher relay
Post by: Elipten on April 13, 2016, 05:35:16 PM
Yes but that 0.1% often bites hard!


Sent from my iPhone using Tapatalk
Title: Re: DIY LED flasher relay
Post by: Nantucket_Red on April 21, 2016, 04:08:51 PM
So it took a week to be able to get back into the shed, as stated I cut the lead on the back of the board and now all I get is a solid light, I can switch back and forth but no blinking. Here is where I cut. I know it's hard to see but I cut what I believed to be the right lead from the pictures shown. I probably screwed up and missed something while reading the posts above. If you have any ideas what to do to fix this, lemme know.
Title: Re: DIY LED flasher relay
Post by: Laitch on April 21, 2016, 04:54:45 PM
Here is where I cut. I know it's hard to see but I cut what I believed to be the right lead from the pictures shown.
I can't even be certain that's the same relay from that photo, Red. Can you shoot another with a pencil point indicating where you cut?
Title: Re: DIY LED flasher relay
Post by: Nantucket_Red on April 21, 2016, 05:15:22 PM
Sorry about that, the cut was made right at the highest point of the line is. Had to do this on my phone because my computer isny working currently. I apologize.
Title: Re: DIY LED flasher relay
Post by: rbm on April 21, 2016, 06:59:14 PM
(https://lh3.googleusercontent.com/-GmGA3ZqNZ1g/VxlaYBtfyHI/AAAAAAAAIB8/g6jW8F7fIMYDOHGUZ6x2bSTluYCxuwcAQCCo/s800-Ic42/cut%2Btrace.jpg)

You should have made a thin clean slice through the trace shown in the diagram above, horizontal in nature, completely severing the connection to the large ground plane island.

Your photo is unclear but it looks like you've taken out some of the surrounding traces.  If you are skilled in electronics, you can repair the damage but make sure you feel confident you know what to do.
Title: Re: DIY LED flasher relay
Post by: Nantucket_Red on April 21, 2016, 07:07:03 PM
Okay, I see what I did. Thankfully I'm decent at sodering so I'll give another go. I can always snag another board. Thanks for the help
Title: Re: DIY LED flasher relay
Post by: cmps on May 10, 2016, 01:59:27 AM
Thanks for this great tutorial, I will do it as soon as I get back to my bike next weekend.

My question is, would this work also with the following setup?
- front indicators -> bulbs
- rear indicators -> led

I still have to decide if I want to go full led or not, so this could be useful.

Quote from: rbm
rbm
Title: Re: DIY LED flasher relay
Post by: rbm on May 10, 2016, 06:31:10 AM
Yes, it will work.  That's what I run on my K75 - front bulbs and rear LEDs.
Title: Re: DIY LED flasher relay
Post by: E30_Crazy on May 16, 2016, 02:03:35 PM
I'm about to try this myself, just to get rid of the hyper flash, but I am getting another curious symptom from the LED swap... My cluster flashers, while hyper flashing, end up getting dimmer over a few seconds, then the next time I activate either side, the opposite arrow flashes on the cluster! The correct indicators flash, but the opposite arrow on the cluster. What a trip! I'll get back once I've made the cut and update whether or not that fixes it.
Title: Re: DIY LED flasher relay
Post by: uhoh7 on September 16, 2017, 04:47:28 PM
What Red shows is there are at least two different boards.


This really confused me, as the board I pulled from my late 84 (build date) K100RS, was nothing like the board in the first series of pictures. I did not see Red's post at first.


(https://farm5.staticflickr.com/4387/37076681276_197084055c_c.jpg) (https://flic.kr/p/YukFBs)
Flasher (https://flic.kr/p/YukFBs) by unoh7 (https://www.flickr.com/photos/55299472@N07/), on Flickr


So the "cut" location in the first series of pics did not make sense. But People talked about cutting pin 7. I did not think the wiring harness was different--I still don't but check me there. So I found the trace right into the mount of pin 7 and cut that.


(https://farm5.staticflickr.com/4342/36429394184_c46abb9cb9_c.jpg) (https://flic.kr/p/Xv9aHb)
Flasher (https://flic.kr/p/Xv9aHb) by unoh7 (https://www.flickr.com/photos/55299472@N07/), on Flickr


Now I have nice left signals but no right ones. LOL


Of course I was doing numerous things at once so, I still am not positive the right handle bar switch is working, but the cancel does for the left, so I think my hack job has caused this. I jumped the pins on the harness, and my right turn comes on switched or not, so I don't have ground or bulb issues.


I think I will order a proper solder kit and see if I can repair, then cut in the location described for Red on the last page.


But what I don't understand: people say cut pin seven. That seems to work regardless of board......or does it?


Anyway my bad cut shown here is the only lead to 7, so why no joy?


TY to all :)


Title: Re: DIY LED flasher relay
Post by: Laitch on September 16, 2017, 07:05:58 PM
I think you've cut a trace to the wrong doodad. The one you want is from the one I've marked with a red arrow in the first photo. That device is found under a red dot in Reply #19 and in Reply #27. Its position differs relative to other components but it's the same device.

(http://www.motobrick.com/gallery/0/1601-160917175818.jpeg)

This photo is your photo rotated 90º counterclockwise. Now it's in the same position as rbm's enlarged photo in Reply #50. I've marked the eight pin solder points with a red rectangle. Which is the trace to the almighty Pin #7? rbm has marked the trace to cut with a red line. I've marked the same trace. It's barely visible at the tip of the yellow arrow. Compare the trace patterns of the two photos; they're identical.

(http://www.motobrick.com/gallery/0/1601-160917182252.jpeg)

Of course, I won't be doing any of this to my bike because I'm infatuated with incandescence; however, you're welcome to discover if I'm correct.  :giggles
Title: Re: DIY LED flasher relay
Post by: austindavidg on October 12, 2017, 07:24:20 PM
Any chance you can get us the pictures in the post above. They're not showing.
Title: Re: DIY LED flasher relay
Post by: Laitch on October 12, 2017, 08:07:58 PM
Any chance you can get us the pictures in the post above. They're not showing.
I'm logged in and they are showing on my Mac right now.
Title: Re: DIY LED flasher relay
Post by: Deepnoizer on October 13, 2017, 08:08:14 AM
Did this surgery yesterday, quick and easy worked great.
You guys are fantastic !
Title: Re: DIY LED flasher relay
Post by: seb on November 09, 2017, 05:35:37 AM
HI, I'm having the same problem with the led flasher (buzz and no flashing) So I ordered a new relais, because I wasn't too sure about what to cut and didn't want to damage the original one. This is what I ordered: BMW K75 K100 K1100 Indicator Flasher Relay (screenshot)

I opened up the relay, and I'm getting something different. :dunno Can someone tell me / indicate what to cut?
thanks
Title: Re: DIY LED flasher relay
Post by: seb on November 09, 2017, 06:13:38 AM
sorry didn't see the following pages. I'll try what RBM told Red
Title: Re: DIY LED flasher relay
Post by: seb on November 09, 2017, 12:24:17 PM
Sorry to relaunch this, but can't really figure out where to cut from the photos. Is it this one?
Title: Re: DIY LED flasher relay
Post by: Laitch on November 09, 2017, 01:28:54 PM
Sorry to relaunch this . . .. Is it this one?
Why are you sorry? Do you think we're doing something important here that you're interrupting? : :hehehe   

Anyway, your board has slightly different paths than the board in the photo you are using for comparison. When you cut that trace, you want to make a careful, thin, clean cut so the trace will be easily repairable. Don't use a machete or a meat cleaver, you'll crack the board.   :yes   You know how to solder, right?

If you have logical reasons for choosing that trace, cut it. That's how I operate. It isn't rocket science; it's more like animal tracking. If you are successful, you'll have gained greater confidence in your reasoning power. If it doesn't work, you will have a good reason for feeling sorry. It's a win/win! :giggles

Report back, please.
Title: Re: DIY LED flasher relay
Post by: rbm on November 09, 2017, 05:38:56 PM
That's the correct trace.  To verify, observe that it goes to pin 7 on the integrated circuit by flipping the board over to the component side and counting the pins from pin 1.  You do know how to identify pin 1 on an integrated circuit, don't you??
Title: Re: DIY LED flasher relay
Post by: seb on November 10, 2017, 03:40:32 AM
Perfect! I'll try this weekend. Keep you updated! Thanks for the help.


[size=0px]To verify, observe that it goes to pin 7 on the integrated circuit by flipping the board over to the component side and counting the pins from pin 1.  You do know how to identify pin 1 on an integrated circuit, don't you??[/size]
[/size]
Not really. I don't know anything about electronics, unfortunately. :dunno [/size][size=78%] But eager to learn :) I'll google it [/size] :yes
Title: Re: DIY LED flasher relay
Post by: rbm on November 10, 2017, 04:36:59 AM
Look at the top of the plastic package and notice there is one end with a notch or moulded indent.  Orient the chip so the notch is on your LEFT.  Pin #1 is the LOWER LEFT corner.  Count pins as you move RIGHT. When you come to the end move UPWARDS and continue to count pins LEFT.


(http://www.amiga-stuff.com/hardware/images/DIP-numbering.gif)
Title: Re: DIY LED flasher relay
Post by: seb on November 12, 2017, 09:53:57 AM
The cut did the trick! Works perfectly, thanks guys.  :clap:
Title: Re: DIY LED flasher relay
Post by: Postman on February 28, 2018, 02:40:27 AM
Thanks for a hint! That was a few minutes job and LED-flashers are flashing like originals :2thumbup:



Title: Re: DIY LED flasher relay
Post by: Fraje on May 31, 2018, 01:46:13 PM
Thanks for all your info! Led-issue sorted easily. Biggest obstacle was to get inside of that relay box. ;)
Also renoverat the BMU while i was at it so the led back/brake light now is ready for the road.
Drive safe!
Title: Re: DIY LED flasher relay
Post by: iliyanTsonev on November 19, 2018, 07:05:58 AM
Hello Guys,

I guess i need to cut the one that i marked with "option 1", but i just want to be sure :)
Title: Re: DIY LED flasher relay
Post by: Laitch on November 19, 2018, 08:43:58 AM
Everest has already been climbed. We've landed on the moon. People are jumping off cliffs in Norway to launch themselves at 100 mph through holes in rock barely wider than their shoulders. Thousands of us are doing handstands and one armed pull-ups at the peaks of skyscapers, and swimming with sharks apparently. People are even kissing lobsters. There aren't many frontiers of adventure left to explore.
This is one of them. Go for it! Don't worry. If you've got "a bunch of BMW cars," you can afford to make a mistake. :giggles

Choosing option Option #2 would be like mistaking shoelaces for spaghetti.
Title: Re: DIY LED flasher relay
Post by: iliyanTsonev on November 19, 2018, 08:49:47 AM
Thank you Laitch,

That's my first post in this forum. Im working on a k100 RS (becoming a cafe racer)

I will let you know what happens after the surgery :)

I will post some of my work soon.

Thanks again.
Title: Re: DIY LED flasher relay
Post by: rbm on November 19, 2018, 09:17:04 PM
I guess i need to cut the one that i marked with "option 1", but i just want to be sure :)
Yes, option 1, not option 2
Title: Re: DIY LED flasher relay
Post by: MEZ on November 19, 2018, 11:45:43 PM
Gents, gonna have to BIG you all up here, this issue has been recirculating around my rather empty 'resolve' chambers for some time now and BOOM..... There it is, the simple solution so big thanks for this thread, however I've not made the 'cut' yet so be on standby ok..!!!


One thing I will add here is my own set-up. I have used GS12 switch clusters on my special build which has thrown in it's own unique set of difficulties. Basically the wiring arrangement to the clusters are CANBUS style. One common feed and eight return switched feeds. Because the 'K' wiring system uses switched grounding paths I have had to implement the use of relays to effect the necessary grounding of each function.


One question here is, will the turn signal 'cancel' function still work after the cut..?? Second question, the hazard warning switch, 3 wires, one is ground so the function of the switch is to ground the (Y/V) and (L/W) wires ???

Title: Re: DIY LED flasher relay
Post by: MEZ on January 23, 2019, 11:01:28 AM



One thing I will add here is my own set-up. I have used GS12 switch clusters on my special build which has thrown in it's own unique set of difficulties. Basically the wiring arrangement to the clusters are CANBUS style. One common feed and eight return switched feeds. Because the 'K' wiring system uses switched grounding paths I have had to implement the use of relays to effect the necessary grounding of each function.


One question here is, will the turn signal 'cancel' function still work after the cut..?? Second question, the hazard warning switch, 3 wires, one is ground so the function of the switch is to ground the (Y/V) and (L/W) wires ???









What can I say, (No photo's needed here), I tried the modification shown on this thread for the first time today along with my own mods (see above) with the GS switch gear and it worked straight off, no messing around whatsoever, it just worked..!!! This I can tell you from pure experience doesn't happen very often in the Electrical Jungle it just doesn't

Thank you to whom ever thought this one through and pioneered it... :hail:
Title: Re: DIY LED flasher relay
Post by: Laitch on January 23, 2019, 11:19:40 AM
What can I say, (No photo's needed here), I tried the modification shown on this thread for the first time today along with my own mods (see above) with the GS switch gear and it worked straight off, no messing around whatsoever, it just worked..!!! . . Thank you to whom ever thought this one through and pioneered it... :hail:
Hello from France too. No need to go to great lengths, just open the existing relay and cut pin 7 to the chip in it. Works fine on mine and I have LED indicators front and back now.
The first person to present this method was bikerboy. Others in thread refined his method down to cutting the trace to pin #7—all significant contributions to the LED-craving community.

Title: Re: DIY LED flasher relay
Post by: MEZ on January 25, 2019, 11:32:39 PM
Laitch, highlighted by someone on another forum (more than likely an inmate on here too) did you or anyone else reading that has gone to LED all round modify the tail/brake wires going to the 'Bulb Monitoring Unit'..?? 

While I'm on may as well be a cheeky sod and ask, fan override switch anyone...??? I have spliced directly into the switched 12v feed to the fan itself from the relay, back feed from the override switch to relay...?? problematic..??
Title: Re: DIY LED flasher relay
Post by: rbm on January 26, 2019, 07:32:22 AM
Laitch, highlighted by someone on another forum (more than likely an inmate on here too) did you or anyone else reading that has gone to LED all round modify the tail/brake wires going to the 'Bulb Monitoring Unit'..?? 
http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/bmu/bmu.htm

While I'm on may as well be a cheeky sod and ask, fan override switch anyone...??? I have spliced directly into the switched 12v feed to the fan itself from the relay, back feed from the override switch to relay...?? problematic..??
There are two recommended circuits for adding fan override. One is to bridge the switch across terminals "A2" and "15" on the temperature relay.  The other is to connect one side of the switch to ground and the other side to terminal "E".  One or the other; not both.  If you've done something else (and it sounds like you have), then yes it is problematic.
Title: Re: DIY LED flasher relay
Post by: MEZ on February 01, 2019, 12:48:15 AM
 [ Invalid Attachment ]

Hi rbm, just checked here on the '86/'89 75 drawing and as indicated the N/O contact in the temp sensing relay has no electrical connection to the other pins so an override switch straight to this wire will only back feed to an open contact and even when temp is reached and the relay is triggered the closed contact will only double up the feed. Should be fine according to that summary I feel. If the supply was coming from the FI unit then yes I think I would have to reconsider as that would be an issue. My next issue is that I'm going to fit an upgraded fan to the radiator so now to look at current draw.....   
Title: Re: DIY LED flasher relay
Post by: Bpmdnb on February 01, 2019, 11:35:17 AM
Another green horn here looking to do the mod for the LED indicators,but before I go bastardizing the relay just want to make sure the circuit board in mine will be the same as what’s gone before. Also I’m going to run an LED strip on the back incorporating the stop/tail light & indicators all in one,will I run into any other issues does anyone know? 1990 k100rs 16v  Thanks in advance 👍  [ Invalid Attachment ]
Title: Re: DIY LED flasher relay
Post by: rbm on February 01, 2019, 01:55:15 PM
No issues.  Here's the sequence of steps:
1. remove the sealant at the base of the module.  It's only a couple mm thick.
(http://www.motobrick.com/gallery/1/270-010219135040.jpeg)

2. you'll see tabs capturing and locking the bottom plate to the case.  carefully bend these the tabs out of the way to release the bottom plate
(http://www.motobrick.com/gallery/1/270-010219174543.jpeg)

3. remove the bottom plate to reveal the board
(http://www.motobrick.com/gallery/1/270-010219135135.jpeg)

4. pull out the board.  This will have SMD parts and not through-hole parts. 
5. Locate U2043.  Identify Pin 1 and then count the pins to locate Pin 7
6. cut the trace on the PCB connecting Pin 7 to the large copper island
(http://www.motobrick.com/gallery/1/270-010219134658.jpeg)

For LEDs on the back, see my recent post about the BMU (http://www.motobrick.com/index.php/topic,12129.0.html).  I'd love to hear if it works for you.
Title: Re: DIY LED flasher relay
Post by: Bpmdnb on February 01, 2019, 05:24:04 PM
Top class rbm,will definitely let you know how I get on,might get to the relay tonight & mess around with LEDs tomorrow. Still plenty left on the project to get through......
Title: Re: DIY LED flasher relay
Post by: Bpmdnb on February 01, 2019, 07:24:46 PM
Fingers crossed for tomorrow
Title: Re: DIY LED flasher relay
Post by: rbm on February 01, 2019, 07:34:46 PM
Verify no connectivity between Pin 7 and any exposed terminal pin on that copper island.  Can't tell 100% that the slice is clean through.
Title: Re: DIY LED flasher relay
Post by: Bpmdnb on February 05, 2019, 10:45:37 AM
Hey Robert,as promised I’d get back to you on the relay hack. Worked a treat thanks for the help,very much appreciated 👍
Title: Re: DIY LED flasher relay
Post by: RetroTexan on July 21, 2023, 12:10:12 PM
Just wanted to add a pic of my relay modification that slightly differs from everyone else's.

This is what the relay on my 1989 K100RT looked like and the cut I made. LED lights work great now!

Thanks for this thread, great advice!
Title: Re: DIY LED flasher relay
Post by: pc759 on July 18, 2025, 10:11:49 AM
Just cut pin 7 on my green flasher relay now I have a squeaking noise as soon as I press indicate and the indicators don’t stay on it’s single press only I think I’m going to go back to 12 v Chinese indicators as that is the only way I will be able to pay for parts for this damned thing