Author Topic: DIY LED flasher relay  (Read 48433 times)

Offline frankenduck

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DIY LED flasher relay
« 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

Five 12V diodes from radio shack: 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:




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.







It's been in my K1100RS and working fine for over two years.
Once I had a Collie pup
Dug a hole and covered him up
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Offline CubPilot

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Re: DIY LED flasher relay
« Reply #1 on: June 18, 2011, 02:55:41 PM »
Dammit Professor, something else I have just got to try!!!!

Offline DirtyF

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Re: DIY LED flasher relay
« Reply #2 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.

Offline bikerboy

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Re: DIY LED flasher relay
« Reply #3 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.

Offline TimTyler

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Re: DIY LED flasher relay
« Reply #4 on: September 19, 2013, 12:15:57 PM »
Updated with images...

Offline TimTyler

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Re: DIY LED flasher relay
« Reply #5 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?

Offline rbm

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Re: DIY LED flasher relay
« Reply #6 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.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline bikerboy

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Re: DIY LED flasher relay
« Reply #7 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?

Offline johnny

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Re: DIY LED flasher relay
« Reply #8 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
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Offline bikerboy

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Re: DIY LED flasher relay
« Reply #9 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.

Offline Doc_69

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Re: DIY LED flasher relay
« Reply #10 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
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Offline Inge K.

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Re: DIY LED flasher relay
« Reply #11 on: November 24, 2014, 03:42:52 PM »
Cut the connection to the leg beside the red dot:

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Offline Andrewck

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Re: DIY LED flasher relay
« Reply #12 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.
1990 K75S

Offline Scott_

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Re: DIY LED flasher relay
« Reply #13 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.
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Offline Andrewck

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Re: DIY LED flasher relay
« Reply #14 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
1990 K75S

Offline enb54

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Re: DIY LED flasher relay
« Reply #15 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...
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Offline Andrewck

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Re: DIY LED flasher relay
« Reply #16 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...
1990 K75S

Offline Andrewck

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Re: DIY LED flasher relay
« Reply #17 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??
1990 K75S

Offline Inge K.

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Re: DIY LED flasher relay
« Reply #18 on: April 19, 2015, 04:26:36 PM »
Another red dot.
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Offline Andrewck

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Re: DIY LED flasher relay
« Reply #19 on: April 19, 2015, 05:45:56 PM »
Blink Blink Blink

It's alive!  Thank you so much!!  Best mod ever.
1990 K75S

Offline rbm

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Re: DIY LED flasher relay
« Reply #20 on: April 19, 2015, 06:19:48 PM »


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.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/
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Offline ts888

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Re: DIY LED flasher relay
« Reply #21 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.

Offline Party Cat

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Re: DIY LED flasher relay
« Reply #22 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!
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Offline Party Cat

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Re: DIY LED flasher relay
« Reply #23 on: July 30, 2015, 06:56:31 AM »
To answer my own question yes that worked!
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Offline Party Cat

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Re: DIY LED flasher relay
« Reply #24 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
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