LED taillight (kz400)

If you have wired it as per the below then the brake light should be brighter than the tail light. I would suggest checking with a voltmeter that you have power on the brake light feed (I know you say the old light works ok) if you have voltage on the blue brake light feed and everything else is wired correctly the lamp unit is probably faulty

 

Tried wiring it like that without any success. My money is on the light being bad but have the resistors coming today just to see if that'll help. If not I guess I'll order another of those lights and hope for better luck unless you have a link to the one you used.

ThatYeti wrote:

Tried wiring it like that without any success. My money is on the light being bad but have the resistors coming today just to see if that'll help. If not I guess I'll order another of those lights and hope for better luck unless you have a link to the one you used.

To be honest if you have the required voltage on the right wire at the right time it only really leaved the lamp unit (I guess at $10 bucks a pop the "quality control" is probably not great )

Ya that's what I'm thinking, reordered another of those lights so if the resistor doesn't help, fingers crossed another light will do it.

Ok, so I had the thing wired up loose and got it to work, showed the running light with the key on and flashed brighter with the lever and but the stop light on the dash was still flashing. Figured I'd just pull the bulb so went on making a bracket for the light, wired it up for solidly...and now I get no running lights no matter what and I can get the dash light to stop flashing with the resistor and brake light works fine.  No idea how or why but hoping that mess makes sense to someone else.

If this is the final version of your wiring I'm not surprised you are having issues, you need to cut that white plug off the light wiring and replace with insulated bullets that will connect to the bikes harness

 

Thanks and no, that was just my attempt to confirm it was all working before I crimped it all and found a spot to hide the wires. Had found a matching harness plug to mate with the one the light has but I think I may just match the factory bullets instead as the whole harness plug I got doesn't inspire a lot of confidence. All that said, why wouldn't I get the same results so long as everything is making contact?

You need to hook up a voltmeter and see if there is power to the light unit when it isn't working

Can't recall if it's with or without the resistor attached but you can see it strobe faintly when it should be showing the running lights solid, so I'd say it definitely has power.

ThatYeti wrote:

Can't recall if it's with or without the resistor attached but you can see it strobe faintly when it should be showing the running lights solid, so I'd say it definitely has power.

The question is "how much" an LED will glow with 2v, the only way to take the guess work out of electrical diagnosis is with a voltmeter

Pulled the connector off and tried wiring them right into the bullets with the new light that came today. Got it to show brake lights at first, but won't light up any more after trying the resistor a few different ways. Also took the new light and pressed the connectors into the clamps on a car jump pack battery and they lit up as expected. What would I check with the volt meter and how would I do it?

Your connections looks like the "Gordian knot", OMG