LED taillight (kz400)

Starting a new thread cause it's just a wiring issue at this point. Not sure what I'm missing but no matter how I wire this new light it still causes the brake light on the dash to flash and I don't get any change in lighting when I pull/press the brakes.

Something different I need to do since it's LED?

The control modul of the "Idiot Light" on the dash register no or to low current flow and will stay on.
You have to solder a ballast resistor (50-80 Ohm) paralell to the LED rear light connection to mimic a fake bulb current load.

Ugh, should have known. Do you have a link to this kind of resistor? And which wire would I need one on?

www.amazon.de/Lastwiderstand-Blinkeranze...rd_i=B09YLJRLP4&th=1

 

Thanks and to confirm I need one of those resistors for each of the wires for the running light and brake light wires? (brown and red and my case). Looks like with this one the diagram shows it only needing one resistor to cover both, but let me know if that's correct:

www.amazon.com/gp/product/B07KS6KMYG/ref...=A6M2FHZLRKPJW&psc=1

Only one resistor for the break light is needed, so fare as i know.
 

Hmmm - I put an LED tail/brake light on my previous '79 KZ400 and did not have any of the issues you're experiencing.

I just swapped out the hardware: the light on the gauge face didn't come on, there was no futzing around with resistors, etc. It was a pretty basic unit from Amazon or eBay; I don't think it had a resistor built in.

Kind of what I was expecting but maybe the one I got is extra amazon-y?

MotoParAcc Red LED Tail Light, Universal Motorcycle Brake Taillights for Harley Dyna, Road King,Yamaha, Suzuki, Dirt Bike and ATV a.co/d/05mnlSR9

It could be that the break light indicator eletronic is disconnected or has a different sensitivity, who knows!?!?

Well the stock one worked fine before I pulled it off and also plugged it back in with no issues. So I think the bike side is okay, guessing it's just an odd setup on the light I picked.

Some early "bulb failure" units look for a ground through the bulb, when the bulb blows the unit looses that ground and put the warning light on. I suspect it isn't seeing the ground through the circuitry of the LED light. The simple answer is take the bulb out of the warning light (you don't need bulb failure warning with LED as they aren't all going to fail at the same time)
Have you tried reversing the brake and marker light wiring (if it doesn't change brightness it sounds like the brake light is coming on in place of the marker light, when you brake it can't get any brighter)

Makes sense, but I did try swapping the marker light and brake light wires but it just lights up the opposite set of LEDs (has one set for brakes and one for running/marker) but gives me nothing when I pull the brake lever.