How to duplicate motorcycle turn signal pilot light

Thread Starter

DBA Dan

Joined Jul 4, 2020
7
Thank you in advance for any advice you can offer, because I'm very much a novice at this. I'm sorry for such a lengthy post but figured I'd at least do the courtesy of explaining my situation as best I can to anyone kind enough to help.

Goal:
Create a second turn signal indicator LED on my motorcycle. The one on my bike (12 below) is mounted way below my field of vision so I sometimes forget to turn off my indicator and the indicator light flashing on the tank remains unseen. Having another LED light flashing - when indicating - at a higher position would help.

The manufacturer's Wiring Diagram
Mine is the Australian (A) version of (10) and (11)
1593907647833.png

Here's what I found and what I tried
I found the GY (grey) and G (Green) circuits Ok, being the left and right indicator circuits (5, 6, 10,11).
If I wired both GY and G to the +ive of the new LED [let's call this (99)], all four indicators would flash as if on hazard lights. Ok - makes sense.
So logically (I thought), I need an XOR between GY and G to power the +ive of the LED at (99) and ground out -ive. Being a newbie, I thought I might place a small SPST relay on each GY and G separately, with only one circuit ever active and the two never meeting to form hazard lights! I used the FRA7TA from JayCar (SY4029). This actually worked soldering to its PCB connectors, but the new LED (99) seemed very dull - so dull that I couldn't see it in daylight - unlike the original at (12) which is very bright. Humm. BTW - there is no access to (12) being in a sealed unit.
I thought the new LED (99) might normally be that dull so thought I might switch it for a small strip of LEDs [call it (100)] which I know to be bright when tested with a 12v battery directly. I figured, even if low voltage is getting to (99) - the combined output of the two relays, replacing the dull lamp with a bright LED strip (100) would be fine.

Now - here's what has really thrown me.

The LED strip (100) didn't even come to life but I did register the smallest dim light on one or two of the 8 tiny LEDs in the strip (100). Didn't expect that! So I wired in both (99) AND (100) at the same time. The dull (99) showed again - as before - and the LED strip (100) remained inactive. But at least (99) was working - even if the LED strip (100) stayed unlit. This is were I stopped - totally confused as to the root cause. Self-admitting, I clearly don't know what I'm doing.

My volt meter, when the indicators are flashing, never seems to read above ~5v when sampled at (99) or (100). I'm not sure if it's because the voltmeter is not sampling fast enough on the flashing line to see it higher or if it truly is low voltage.
My gut tells me that it's voltage from the two new SPST relays (2x FRA7TA) may be too low, but they're both 20AMP 12 relays. Perhaps having the output of the two relays joined to a single +ive out has halved my voltage for some reason - say "reverse" powering the other relay which would always be idle. I hope this makes sense?!

Where to from Here?
If I have to start again - that's Ok. I'm happy to do it all over as a learning experience.
I did wonder if I used the (possibly) low voltage I am getting to trigger a 3rd new relay then pull a full 12v batter power directly through the 3rd relay, that might get me the result I want, but I feel that I'm over-complicating it to hell and better to ask.

I'd be very grateful for any assistance/advice.
 

shortbus

Joined Sep 30, 2009
7,761
Not real sure where you're getting your #99 and #100 from. But, that aside it looks like the existing bulbs/indicators are incandescent normal light bulbs correct? If so they are what is dropping your voltage. Why not tap into what looks to be the "orange(o)" wire at the turnsignal switch or relay(assume that means flasher unit)? You don't need to know whether it is left or right flashing just that something is flashing. The O orange(?) lead is full battery voltage so should drive the LEDs to light. This can be verified before making wiring changes by measuring voltage from orange to ground. Like earlier due to the schematics pixelation I'm assuming it is orange.
 

Thread Starter

DBA Dan

Joined Jul 4, 2020
7
Not real sure where you're getting your #99 and #100 from. But, that aside it looks like the existing bulbs/indicators are incandescent normal light bulbs correct? If so they are what is dropping your voltage. Why not tap into what looks to be the "orange(o)" wire at the turnsignal switch or relay(assume that means flasher unit)? You don't need to know whether it is left or right flashing just that something is flashing. The O orange(?) lead is full battery voltage so should drive the LEDs to light. This can be verified before making wiring changes by measuring voltage from orange to ground. Like earlier due to the schematics pixelation I'm assuming it is orange.
Thank you Shortbus. I'll test that out.
BTW, (99) is the label I gave to the first-added LED pilot light and (100) is the label I gave to the 2nd-added LED strip.
Just out of interest - testing the manufacturer circuits at 5,11 and at 6,10, the voltage does read the full 12V. So would you expect the relays I added might be causing the voltage drop?
 

shortbus

Joined Sep 30, 2009
7,761
Just out of interest - testing the manufacturer circuits at 5,11 and at 6,10, the voltage does read the full 12V. So would you expect the relays I added might be causing the voltage drop?
I don't think so, relays are usually used to give less voltage drop. But then again I don't know how you connected them.
 

Thread Starter

DBA Dan

Joined Jul 4, 2020
7
Current wiring:

LHS TURN SIGNAL WIRE (12V) --> SPST Relay 1 --> Connector X
RHS TURN SIGNAL WIRE (12V) --> SPST Relay 2 --> Connector X (same as above)

Connector X --> now 6V = The Issue
-----------------------

Some extra testing has found the cause of my voltage drop. The outbound line of the two relays comes together and when LEFT signal is active, its relay passes power through fine and visa-versa for RIGHT to the other relay. But because both outbound lines come together (Connector X), there's a "backfeed" into the idle relay which halves the outbound voltage showing only 6V. I've proven it by disconnecting one of the relay outbound feeds and boom - the remaining line returned to full voltage.

Ok - so how do I prevent this backfeeding?
One gents suggested replacing the relays with resistors on each line, but I can no longer find his reply. I'm not sure resistors will do what I want, but I again confess that I'm no expert. My own checks suggest that a diode would prevent backfeed. So does that suggest I need to solder a diode in line of the two outbounds after the relays? I can't help but think I'm over-complicating this.

Any guidance would be great.
 

Thread Starter

DBA Dan

Joined Jul 4, 2020
7
Another update.....

It looks to me like this diode would do the trick.
Diode 1N5822 Schottky 40V 3A D027
One of these soldered into the outbound leg after each SPST relay before joining the common connector should prevent the current backflow to the sibling idle relay and (I figure) will give me the full 12v (less a bit for the diode) to the common outbound.

Please consider this me just trying hard to educate myself and not rely totally on others to spoon feed me. If I'm wrong (again!), I welcome that as a learning experience.

If someone could validate my thinking/plan here, I'd be very grateful. If Ok, I think it would achieve the end result I'm looking for to power a simple duplicate turn signal indicator light - one that is within my field of vision when wearing my helmet on the motorbike with my head in the ideal position watching the road.

Of course, if someone says "Hey, you can do all this a more efficient way by ...." then I'm all ears. Being such a noobie, it's all good learning.
 

shortbus

Joined Sep 30, 2009
7,761
Some extra testing has found the cause of my voltage drop. The outbound line of the two relays comes together and when LEFT signal is active, its relay passes power through fine and visa-versa for RIGHT to the other relay. But because both outbound lines come together (Connector X), there's a "backfeed" into the idle relay which halves the outbound voltage showing only 6V. I've proven it by disconnecting one of the relay outbound feeds and boom - the remaining line returned to full voltage.
Your doing it again, using things that only mean something to you. Draw a picture also known as a schematic, that lets others see what you're doing and we can talk about it both knowing what is happening.

Why are you using relays at all on turn signals? I've modified and built vehicles for most of my life, since I was a teenager and am now 72. I have never used or even seen relays with turn signal wiring. Not trying to be difficult just trying to understand the reason.
 

Thread Starter

DBA Dan

Joined Jul 4, 2020
7
Hello Shortbus and thank you for taking the time to reply.
In each instance where I'm referring to a term that I've created, I've defined that term in advance. If you read my notes, you'll see them explained. You'll also see explained in detail why I'm using relays, but you've asked "Why?"
RE: schematic. I've also tried to provide that too - textually in the section marked "Current Wiring".
I've also stated the overall objective so that anyone can suggest a totally different approach if they see a better way. I invite that again now.
 

Thread Starter

DBA Dan

Joined Jul 4, 2020
7
By the way Shortbus. I completely agree with your comment about using relays. They were only to keep the two circuits apart to stop the "hazards lights" effect. But I hadn't counted on the backfeed into the idle relay draining 50% of the voltage.
I've given more thought to this and wonder if I should replace both relays with diodes (Diode 1N5822 Schottky 40V 3A). If the diodes stop the backfeed down the idle circuit, then I suspect this will achieve a resolution to the "hazard lights" issue bringing the circuits together - without relays. This might provide a single +ive line out of the two diodes that will be active when either turn signal is active - giving me a +ive to an LEDTurn signal indicator Diagram.png indicator.
Something like this hand-drawn schematic showing the LHS and RHS turn signal circuit feeding into diodes and a single line out to the new LED indicator.

Thoughts?
 

Thread Starter

DBA Dan

Joined Jul 4, 2020
7
Pleased to report that I worked this out. Diodes did exactly what I needed. Replaced the two relays with Schottky 40v 3A diodes and bingo. All good learning experience.
 
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