LED woes never end! [1978 GS400]

[ItsBork]

Long time no post. I've been busy with a move and getting all the finer bits right with the bike, but I've hit a wall with the lights.


I am having two separate problems that may or may not be related.


First, I cannot get my signals to stop blinking erratically. I have stock front signals and LED rear signals. Signals seem to work fine when under throttle but act erratic when idling. They will blink fine for a few flashes and then do a few erratic flashes and then go back to normal.

What I have tried:

- installed LED compatible flasher relay

- installed diode kit on dash light

- checked grounds and other connections

Second,
I have an LED "underglow" kit wired to my bike (Yes, I'm THAT guy.) And I am having an absolute nightmare of a time getting it to work properly.

It works absolutely fine when the bike is off, but when the bike is running, it will randomly turn off. It's only for a couple seconds and then it comes back on. Sometimes it stays on for a minute or two sometimes only a few seconds. It is not fully power cycling (the lights are the set color when they come back as opposed to coming on white first like when they are first powered on), but the lights are completely cutting out. There doesn't seem to be any correlation with throttle speed, it behaves the same when riding or idling.

What I have tried so far:

- Different sources of power including ignition coils, the fused connection at the battery, the brake lights, and directly to the battery itself.

- new grounds

- installing a stepdown regulator to keep the voltage locked at 12v (I was wondering if the 13+ volts when riding was overloading them)

- reducing the number of led strips all the way down to 1

I have checked voltage while the bike is running and the strips never lose voltage even when they cut out.

I have replaced the stock regulator and rectifier with an SH775A unit to remedy the common overheating wire issue and hopefully solve these two problems. It didn't seem to make a difference. Battery is standard, about a year old, and holds charge fine.

Nothing seems to improve the behavior. At this point I'm wondering if there is simply an issue with the LED driver itself. It just seems odd that it would behave differently when the bike is running even when it's wired straight to the battery.

Figured I'd get some feedback before I just replace or remove the strips and try to find a way to go back to the old rear signals. (PO shaved off the mounting brackets)

[Gorminrider]

As to the light strip acting up, it might be connected to the turn signal issue....but I would disconnect it entirely and get the signals working FIRST.
I've had led turn signals for years with no issue whatsoever even though I know there's no really good reason to replace the incandescents...so really, you can save a lot of effort going back to incandescent throughout, with the original parts and then fiddling with the lightstrip.
But if you are determined:
Do you have the schematic of what you did? Firstly I don't know what an "LED compatible relay" is unless it's a 3 wire type. You said you have one turn signal dash indicator. That's ok..there's a circuit for that -the diodes mentioned or...( I even replaced my single with two tiny 12v leds jammed into the same hole being simpler than an incandescent AND diodes) . and What are you using for the led turn signals? I use led bulb replacements in the original stalks.

[ItsBork]

I'd love to go back to the stock signals, I still have them. The problem is the PO shaved off all the brackets on the rear end (signals, side covers, seat, helmet lock) when he modified the rear end for a cafe seat. I haven't figured out a good way to mount them without access to a welder. I may try connecting them and seeing if that somehow solves the light strip problem, stranger things have happened.


The relay I'm talking about is here. Not sure what makes it LED compatible, just know it's a common remedy with LED signals.

https://www.amazon.com/gp/product/B08JPBCBR6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Diode kit is here, it's installed inline with the dash indicator wire.

https://www.amazon.com/gp/product/B01DYS3A56/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The led signals I'm using are here:

https://www.amazon.com/gp/product/B07YYBRH3G/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

[Gorminrider]

Oh gee. I think your diode thingy for the dashlight should be ok -it's testable and the wattage isn't much in the circuit that should be used...but those leds- they've got two "Funcations" and are bit too clever bMy experience has informed me they are a risk and I wouldn't get a thing like that without a working system that I can return to .
...The two-prong relay...mmm. I think I would have gone for a real Tridon brand . But, can you get the one you have to function on the running bike WITHOUT the Led Funkator? The main requirement for "led blinker conversions" is that the relay is independent of the loads it is blinking so it should work. This will also hopefully get rid of the idea of crazy AC voltage in your circuitry...(and some "Funcators" use some really doubtful/sensitive chips...)
if you want to start afresh, I can draw up a working circuit that I use for 3 connection relay because I can't find a link to one that is completely comprehensible... but carry on with the "two" you have until it's known bad.

As to PO chopping off the frame, is there ANY access to a bit of tube frame you could wrap a metal strap around and then bolt signal stalks to it?? ie: bend a thin piece of metal strap into a U-shape and use a bolt through to clamp it tight to tube? ie: the way things are clamped to handlebars?
Or, You could maybe lash/clamp a bar to frame under the seat and attach signals to it? (don't sneer at "lashings"..nylon net-twine stretched tight on many turns can crush steel pipe and is immoveable).

[ItsBork]

Yeah I'm in a bit of a rough spot because I'm not sure where the issue lies and the only way to really pin it down is to play whack a mole. I know the relay works fine with the stock signals as I had them hooked up to test the electrical system when I was building the bike. I'm starting to suspect it may be the issue though, so if you have any recommendation on a known good one or how to build a good circuit I'd love to hear it.

I do think I could rig something up with some strapping or possibly even some cheap handlebar clamps. There's plenty of exposed tubing in the back as the PO added a round extension for the seat. The bike is pretty rough aesthetically so I'm not super concerned with it being super "clean" looking. I would definitely prefer to go with the stock signals as I like the look and that's what I use on the front.

Now I just need to figure out what to try next for these light strips. I'm starting to wonder if they just plain don't like the electrical system in these old bikes. Most of the people installing them are riding stuff made in the last 25 years and I know the GS has a bit of a weak electrical system even with the reg/rec upgrade.

[Gorminrider]

Ok. I'll make a sketch up and take a picture of my relay. They ARE cheapos from ebay (amazon will have the same) but have been good. Cheap enough to buy a spare.

Yes it's frustrating. I too often run around in circles giving life to the handy homily: "repeating the same experiment hoping for different results is the path to insanity" I haven't crossed your interference idea off the list either...maybe your lowish charge voltages might indicate the regulator has blown a junction and is letting AC through.

It's maybe not because our bikes are old. Kind of the opposite in some ways. I think lots of people have bought various doofunnies and discovered they are not compliant with the computers in newer vehicles...but ywho knows with this stuff... I've had to short out chips in so-called cobb leds because they'd suddenly start to strobe. They got the idea somewhere and it wasn't from me pushing the button.

[Gorminrider]

Well,, know I remember why I didn't save a diagram...it's too simple. I used the original connector on the new cheapo ebay relay. The wire colours in the pic are Light Blue, Orange and Black.
Black is the "extra" and it goes to ground (E ="earth" on the relay)
Orange is + power (("I"=current? on the relay)
LtBlue goes to the handlebar Turn switch.("L" = load on the relay)
Then with the two diodes at the indicator* job done.

just a thought-I can't remember but it's possible I swapped the Orange and LtBlue in the white plastic to suit the relay's connections?

Turn signal LED relay Gs400EX.jpg

*I use two 12v leds crammed in to the gauge's place as a clever simplification that -well- maybe isn't so clever or better but I have them so need to use them somewhere...

[Gorminrider]

Circuit for LED signals-3post relay and single indicator.jpg

Sketch of circuit wire colours suiting older Suzukis....for someone with two indicators, the diodes wouldn't be "married" -just one per indicator.

[ItsBork]

Well you'll never believe it, but I solved it! And it was all thanks to a thread here. There's a guy who was having hyperflash on his signals and solved it by switching to resistor plugs. Well, I checked my bike and sure enough I was running B8ES plugs. Went and snatched a couple BR8ES from AutoZone, gapped them, and slapped them in. Fired it up and turned on the signals and lights. All good! Just got back from a solid 30 minute ride and made sure to use the signals a lot and didn't notice any erratic flashing. I didn't notice the light strips cutting out either but that's harder to watch in the daytime. Let it idle with signals and lights on when I got back and everything seems good! So it looks like the noise coming off my coils was just causing absolute havoc with the aftermarket lights. That makes sense considering I'm on aftermarket electronic ignition and coils.

Thanks a lot for the diagrams! Those might be helpful in the future and I'll share them on the Facebook groups.

[Gorminrider]

hey Great! We learn something new!
Funny because there's lots of threads here where people are arguing to get rid of resistor plugs! and perhaps that's what your PO did...I wonder-does your bike have the original resistor spark plugcaps? or did the PO get rid of them too...it should be about 5k ohms resistance through just the caps.

[ItsBork]

The entire ignition system has been replaced. I'm running Dynatek coils and wires and caps.