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Discussion Starter #1
Hey all,

My latest project is making my own tail chop kit with my own set of lights,blinkers and brackets. I have the blinkers and the bracket working but I can not figure out the brake light wires.

Ok so coming out of the brake light you have a yellow, red/grey, and black wire soldered to the side of the bulb housing. The black is the ground which tied into the blinkers ground, but its not the ground for the brake light.

My new brake light has 2 wires Red and black, I tried tying the them in all different ways no luck except for blown fuses to let me know I did something wrong.

Do you guys know if the yellow or the red/grey needs to be grounded?

I looked at the schematics but its no help, and yes my new brake light works as I have tested it with the blinker wires.

You help is always appreciated. Thanks
 

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Hmmm... does your new brake light have a dual filament bulb, i.e. parking and stop light. If it has two filaments, the ground is the body of the stop light not either of the two wires.

Sorry can't help beyond that. I'm too many miles away from my bike.
 

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Discussion Starter #3
My brake light has 3 wires actually black, red, and yellow. When I asked the supplier what the yellow was for he said it was for the license plate lights. However, I think he is wrong, and maybe one of those lights are a second stage (when you depress the brake it gets brighter)

AS for dual filament, they are LED's I am not sure. But the unit is a brake light.
 

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LEDs will confuse the issue also as they act like one way valves. If you reverse the power and ground leads they will not light up as a normal bulb.

It probably is a parking-light/stop light combination, as you think. More LEDs light up and act as the stop light. If there is a clear window at the bottom of the brake light then the parking light is also acting as a plate light

If somebody can't come up with the wiring diagram I suggest you get a test light or a multi-meter and figure out which lead on the bike goes hot when the bike is turned on and which one goes hot when you depress the brake lever.

It is a good assumption that the black wire on your new light is the ground but don't assume that on the bike (The stock license plate circuit, I believe, the brown wire is ground and the black is power!) Figure out which lead on your new brake assembly is brighter. You can use your battery tender lead (hopefully you have one) to test the light as to which is the brighter element.

Good luck.
 

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Hey all,

Ok so coming out of the brake light you have a yellow, red/grey, and black wire soldered to the side of the bulb housing. The black is the ground which tied into the blinkers ground, but its not the ground for the brake light.

My new brake light has 2 wires Red and black, I tried tying the them in all different ways no luck except for blown fuses to let me know I did something wrong.

Do you guys know if the yellow or the red/grey needs to be grounded?

I looked at the schematics but its no help, and yes my new brake light works as I have tested it with the blinker wires.

You help is always appreciated. Thanks
Looking at the wiring diagram (from a Paul Smart, but I would think they are all the same) ...

Black - Earth (ground)
White/Black - Indicator
Yellow - Taillight & Number Plate light
O (Orange?) - Indicator
Grey/Red - Brake light


The black is going to be ground for all lights, including the brake and tail light. In the original assembly, the lightbulb is a dual filament (two lights in one) using three connections - 1) a common ground connection 2) brake light 3) tail light.

Your new brake light, from your description, is the equivalent of a single filament lightbulb. You should connect it's black wire to the black wire of the bike, and the red wire should be connected to either the yellow or the grey/red, but not both!!!!

Do not ground any wire except the black !!!!

Is your new light an LED unit? If so, you will most probably need to put a resistor in series with the wiring which will reduce the current flowing through the unit.

Also, if it is an LED unit, and it needs a resistor, then it is possible to wire it so that it works as both a tail light and a brake light.

If you can provide me with more details of your light assembly, I can provide a wiring diagram.

Cheers

Rob
 

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Also, if it is an LED unit, and it needs a resistor, then it is possible to wire it so that it works as both a tail light and a brake light.
You only need resistors for LED turn signals to make the flasher work right. A tail/stop light should not need them.
 

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Discussion Starter #7
Ok here is the Unit. LED brake light with window on the bottom to shed light on the license plate. There are three wires red, yellow, and black. So coming out of the stock brake we have black, yellow, and red/grey.

Thanks guys

 

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Discussion Starter #8
Ok I am off to bed. I will try and post at work tomorrow but probably will not be able to reply until 4pm EST. I will try out what ever you guys come up with tonight, tomorrow when I get back. Cheers
 

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Ok here is the Unit. LED brake light with window on the bottom to shed light on the license plate. There are three wires red, yellow, and black. So coming out of the stock brake we have black, yellow, and red/grey.

Thanks guys

OK, not a lot to go on with just a picture.

You have three wires coming out of light, so you are heading in the right direction for hooking up the unit.

Without knowing what is inside the unit, at this stage, I think you must need some resistors in series with the red and yellow wires.

Did you get any information with the unit? Else, where did you buy it from? Any details on their web site?
 

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All I can suggest at this time is to put a resistor in series with the yellow and red wires. This will prevent blowing fuses.

As a starting point, try getting two 470ohm resistors. I don't know where you live, but try a Tandy store if there is one.

To connect :

1) connect one end of a resistor to the red wire coming out of the light assembly, and the other end to the grey/red wire of the bike wiring

2) with the other resistor, connect one end to the yellow wire coming out of the light assembly, and the other end to the yellow wire of the bike wiring

3) connect the black wire coming out of the light assembly to the black wire of the bike wiring

If this works, the light should work, but it will most probably be too dim, but you will have at least worked out that you have the right wires going to the right places. It is then a case of working out the correct resistor values to get the right level of brightness.

Good luck.

Rob
 

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Discussion Starter #11
Ok I will head to Radio Shack after work and get some resistors. FYI: to test the light original I used the 2 wires feeding the original license plate light. I connected the power wire to the yellow of my new LED brake light and the other I think brown to the Black wire on my LED brake light and it light up with no problem.

Is the power coming off the brake light wires different then the blinkers and the license plate light that I need the resistor?

Also what resistor value will slow down the blinking rate?

Thanks I will try everything when I get off work. Thank you all!
 

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LEDs

I hope the following helps.
Basically a Light Emitting Diode (LED) is a diode that give off light when it is forward biased (conducting) and no light if reversed biased (voltage reversed). When a diode is forward biased it is a short circuit and when reverse biased an open circuit. If your tail light assembly has no inbuilt resistors to limit the current flow it will be a short circuit when you put the 12 Volts on it and it will blow fuses. I would be surprised, or equally not surprised, if there are no inbuilt resistors and you have to supply some external ones to limit the current flow. So the suggestion for a 470K resistor in the 12V line is a good suggestion. The wattage of this resistor depends on the number of LEDs in your tail light. In the bad old days when I was actually working with this stuff a rule of thumb was with 5V supply use a 470K quarter watt resistor and and one LED would give a good brilliance. Of course LED technology has progressed a lot since then, but if you are going to try a resistor I would suggest a wire wound resistor of a couple of watts power rating and a value of 470K. If it then works on both the red and yellow (brake and tail lights) wires with the black as earth, adjust resistance value for brightness, lower resistance = more brightness. Also check resistor doesn't get too hot to ensure it doesn't burn out or cause other problems.
 

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Discussion Starter #13
Thanks


I may not have been clear in my first post and I did not answer a question few posts above.

1. I only blew a fuse when I shorted one of the yellow or red/grey wires to the ground wire. I never blew a fuse when connecting any combonation of wires to the LED brake light wires.

I will go out and buy some resistors, but I suspect that the assembly has built in resitors (I will open up the unit later and take some pics)

2. The unit does not come with any documentation, and the seller had no clue when I asked about the 3 wires. He said that one wire was brake light, the other wire was the license plate light that shined through the window, and the other was ground. No I need to open up the unit, but I think he maybe wrong; there is no license plate light, all the light comes out of the window from the refelection of the brake light. So one wire should be for when the brake light is always on and the other should be when the brake is applied to make the light brighter or light up more LED's
 

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It sounds like a good idea do have a look inside. if there a are no internal resistors you may blow up the LEDs with power applied to them.
You could remove the battery from the bike and use it as a bench 12V power supply to test the light assembly which takes the bike switching and wiring out of the equation.
Black is nearly always negative, so you could then put the yellow and red wires separately, and then together, on the positive terminal to see the result. But determine if you need an external resistor first to make ensure you don't blow it.
 

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Discussion Starter #15
The brake wires off the harness from the bike should be no more than 12V correct? If so, my LED Unit says 12V. I will put a meter on the harness later.
 

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Thanks

I may not have been clear in my first post and I did not answer a question few posts above.

1. I only blew a fuse when I shorted one of the yellow or red/grey wires to the ground wire. I never blew a fuse when connecting any combonation of wires to the LED brake light wires.

I will go out and buy some resistors, but I suspect that the assembly has built in resitors (I will open up the unit later and take some pics)
OK, shorting one of the yellow or red/grey wires to the ground wire will definitely blow a fuse.

From what you have now described, I doubt you need resistors. It would be very strange that they wouldn't put them inside the unit.

To wire it up, I would try:

1) connect the red wire coming out of the light assembly to the grey/red wire of the bike wiring

2) connect the yellow wire coming out of the light assembly to the yellow wire of the bike wiring

3) connect the black wire coming out of the light assembly to the black wire of the bike wiring

If you feel that the light balance between just tail light and when the brake light is on, then try connecting the yellow and red wires the other way round.

If you have a meter, measure the resistance between the black wire and the case of the light assembly and you should see very low resistance, almost zero. Then measure between the yellow wire and the case, and the red wire and the case and you should be seeing a hight resistance, greater than 10kOhm.

Good luck.

Rob
 

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Discussion Starter #17
Ok guys I was almost about to bang my head against the wall but the last test worked..... kind of.

Ok here is what I know:

Out of the harness from the bike, Yellow is brake light, red/grey is Brake light when brake is applied, and black is ground.

Out of my LED brake light: Yellow is Brake lights, Red is brake lights when applied, and black is ground.

So I connected yellow to yellow, red/grey to red, and black to black....nothing at all. I then tried swaping red and yellow, then doubling up yellow, doubling up on red....nothing

Now I am thinking something is screwy with my LED. So I took one of my new LED blinkers which have 2 wires black and yellow... I conected black to black and yellow to yellow.. It works this gave me the brake light when brake is not applied.. then I attached the yellow to red/grey and when I pressed the brake it worked...Ok so I know the harness is fine so maybe my Brake LED is screwy.

I then proceeded to test my Brake LED with the license plate light harness which is which is a 2 wire setup brown and black. So black to black and brown to yellow and the brake light worked. Then I took the red/grey wire from the other harness and attached it to the red wire on my Brake LED now when the brake is pressed it gets brighter.

So unless I am missing something, this is how its going to work:
Using the License plate light harness coming out of the bike I will ground the unit and power the brake light, then connect the red to the red/grey of the other harness to make the brake light brighten when the brake is depressed.

This leaves the solid yellow wire on the blinker brake harness coming off the bike unused.

Does anyone see a problem with this setup besides being totally weird?
 

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Discussion Starter #18
Ok so I did a ruff mounting. I still need to mount the blinkers. I purchased cat eye blinkers that I was going to mount on each side of the brake light but now I may try and find blinkers that attach to the license plate nuts in place of the reflector license plate nuts. But I don't know.

Read the post above to see the crazy wiring that had to be done.


Oh and thanks to everyone who posted, much appreciated.
 

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NO!!!! You may cause some other funny problems with the taillight license plate light feeding voltage back through the brake light circuit. You most probably won't, but I have seen weird things happen in the past.

OK ... something else to try ...

First, I thought before that the black wire might also be connected to the case of the light, but this is most probably not true. The LED assembly is most probably fully isolated. But it could be worth while measuring the resistance between each wire and the case, and if one of the wires is connected to the case, then this will be the ground or negative wire.

Take the unit off the bike so there can be no accidental grounding and blowing of fuses.

Run two wires from the battery of the bike, or your car, or any spare 12 V battery. And then try:

1) Connect black wire to negative of battery, then connect yellow wire to positive of battery, see if any thing happens. Then connect red wire to positive and see if any thing happens.

2) Connect yellow wire to negative of battery, then connect black wire to positive of battery, see if any thing happens. Then connect red wire to positive and see if any thing happens.

3) Connect red wire to negative of battery, then connect yellow wire to positive of battery, see if any thing happens. Then connect black wire to positive and see if any thing happens.

If one of these combinations gives you the expected result, i.e. both brake and tail lights work, then you have worked out your wiring.

If none of these combinations work, then you have a faulty unit.

Or, you might see that in only one of the above that only one section of the light lights up, in which case, the unit is half faulty.

You will not cause any damage putting a reverse voltage across LED's - they only conduct current in one direction.

Cheers

Rob
 

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Discussion Starter #20
REH thanks for all your help, I will try rewiring and testing tomorrow based on your new suggestions.
 
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