LED taillight (kz400)

Yes, as it just shows 0.00 when it's off.

So with the ignition on you have 0 Vdc on the red wire (bike side) ? and with the brake light activated you have 0 Vdc on the blue wire (bike side) ?

Are you sure the meter probe is making good contact with the connector under the rubber sleeve ?


 

Yes to zero voltage with ignition on to the red wire (brake light) and zero voltage to the blue wire (running light) regardless of the ignition on or brake being pulled.

I can hear a click when the probe makes it over the lip of the bullet connector under the cover so I would say yes but I can try again and wiggle it around I guess.

Will also add that the resistor has little taps that came with it but I didn't want to hack up the wiring to try to and with the bullets plugged in there isn't any room to sneak them in to try otherwise.

* Checked again and the running light/blue wire jumps between 0.00 and 0.01-0.05 which coincides with the flashing of the brake lamp light on the dash and the flickering/faint strobing of the running lights on the tail lamp.

From the diagram I looked at blue is the brake light and red is the running light, if the readings don't improve unplug the bullet connectors and put you red meter probe into the bullet connector on the loom side, what do you get now ?
If the readings are still low move the black meter lead to the battery ground terminal and measure the blue and red again
 

So the different wire colors aren't helping but the bike side wiring is:

     Black - Ground / Red - Running light / Blue- Brake light

the lamp wiring is:

     Black - Ground / Brown - Running light / Red - Brake light

Black-Black
Red-Brown
Blue-Red

Will try pulling the running light connection apart to see if I get anything different numbers wise as I think that's what you're asking but let me know if you're asking about the brake light.

*Edit - Tried that and ruined the wiring cause the bullet connector wouldn't come out...which is why I didn't want to wire any of this solidly until I was sure what needed to be done...

That said I ran the red lead on the tester to the red wire coming from the bike and got a solid .155 and the tail light would lightly strobe and the dash stop lamp light would flash as well.

Was this with the red wire disconnected ? Where did you have the black meter lead ? when the red wire is disconnected it should be a straight ignition live from the ignition switch (are there any other mods to the wiring)

Yes I tested it with the connection apart like you suggested and plugged the red probe into the red connector from the bike side, which I think it why I got a steady .155 reading. No other modifications to the wiring I'm aware of, only change on this end would be the tail lamp I'm adding. Otherwise I replaced the front blinkers with LEDs, head light with an LED unit and replaced the flasher relay with an LED compatible one.  Also rear blinker wires are hanging disconnected at the moment, wanted to get this resolved before I plugged those in.

Where was the black meter lead connected - you should have full battery voltage here with the ignition on
You can also do the same test on the blue wire (disconnected, ign on brake operated) this should also be battery voltage - I would try twisting the connector with long nose pliers when you pull it apart so hopefully it won't break

Black lead was on the negative battery terminal.  Blue (brake light) wire seems to be working 100% so I'm not sure what pulling that apart is going to do but ruin another connector and shorten the wires I have to work with.

ThatYeti wrote:

Black lead was on the negative battery terminal.  Blue (brake light) wire seems to be working 100% so I'm not sure what pulling that apart is going to do but ruin another connector and shorten the wires I have to work with.

I suggested checking the blue also because the results you are getting don't make sense - this is a basic circuit !!!
Can you re-do the test on the red where you get 0.155 and post a picture that shows your meter and connections - this comes direct from the ignition switch - 
Also without pushing the brake there should be no power to the lamp unit so why is it "strobing" (I think it is seeing a voltage leak from the bulb failure unit - at the end of the day you are combining modern technology with a 50 year old electrical system)

Thanks but really not interested in ruining more wiring, don't have any confidence that connector is going to come out in one piece. Is it possible to just wire it straight to the battery? It's meant to be on all the time anyway and it's pretty close to the terminal.

ThatYeti wrote:

Thanks but really not interested in ruining more wiring, don't have any confidence that connector is going to come out in one piece. Is it possible to just wire it straight to the battery? It's meant to be on all the time anyway and it's pretty close to the terminal.

Get your concern with the wiring so here is a plan "B"
Disconnect the plug to the bulb failure relay (the brake light should then work as normal without the bulb failure light in the circuit)
Re-test the red and take a photo as I suggested (it's already disconnected - I suspect the issue is the way you are testing it rather than a fault with the bike)
If you wire it direct to the battery it will be on all the time with or without the ignition and will drain the battery

If you are going to modify your bike you need to expect some "bumps in the road" and have the patience to see it through. The internet is full of "unfinished projects"