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Discussion Starter · #1 ·
I am working on a project bike where the previous owner butchered the wiring that leads to the LED license plate light, by adding more lights to that wiring cable. using non-correctly-color-coded wiring!

I bought a new LED license plate to replace all the lights that were on the old circuit. I have 2 problems:

1. The new LED license plate light did not come with any wiring instructions at all. Just a black wire and a red wire. Is the red wire the "12 volt+" wire and the black wire the "ground" wire, as I would expect?

2. The previous owner spliced into the OEM connector cable right behind the OEM connector that attaches to the bike's wiring harness (Yes, I wondered why too), and then wrapped all the splices, for both the 2 OEM wires (red and black/yellow) and the SIX un-color-coded wires (all black) that fed 3 different lights, with so much electrical tape and TIGHT heat shrink tubing that I cannot disassemble the wires to see what was conencted to what else!!

So, I figure the easiest way to handle this is to leave the "bundled wires cable" intact and simply find 2 wire ends out of the 6 bundled wire ends, that actually produce light at the LED.

But, knowing nothing about LEDs, can this trial and error approach kill the LED if I make a wrong polarity connection?

Jim G
 

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Well, for a guy that seems to have a PhD in exhaust science and fueling (yet the only one with a handwritten dyno chart), and no fuel map..... Get the Delkevic tuned or run as is, hopefully you'll be fine, and glad your's seems to be running well and cooler; just don't bash the vast majority that get tunes and have concrete/proven dyno/fuel charts from before and after.

Seriously though, your question above seems pretty simple. Here's my thoughts as someone who's done a smidge of 12v stuff.
You left out too many variables, like model (assume N400, or Z400), what year? Also, did you get the full housing or just a bulb? Tail tidy or OEM tail section? Is it the wiring for license plate light only or does it mess with brake light and turn signals.

1 - Do you have a multimeter? Honestly this will probably help you figure out all the problems. Fluke makes great stuff, but even a moderately priced unit from Home Depot or somewhere like that will do the task. Sounds like you need to be able to measure polarity, and voltage.
2 - I would assume 99% that black is ground and red is positive. The polarity part of the multimeter should tell you that. Perhaps take a 9V battery and touch the red to the positive and black to the negative. If that works you should be good to go. Highly doubt you'll do damage to it. LED's are very durable and highly resistant to voltage irregularities and physical abuse, which is why they're they predominant technology being used. Last way longer than incandescent and HID and draw a ton less voltage. Longer lifespan many times over means less business for light manufacturers. Most of the reason it's not everywhere is the initial cost used to be a good bit more, but that gap is narrowing, as such it's becoming more common.
3 - If it's a project bike as you say, I'm guessing you want to get rid of anything superfluous? If it were a project of mine I definitely would. As such I'd remove any of the auxiliary lights, and all of that trash cable. Cut the heat shrink and get rid of all that crap. If I were doing a project I'd want everything done right and wouldn't want the electrical equivalent of Pandora's box hanging out in the background.
4 - I'm guessing you're just talking about the LED tag light? Doesn't the OEM tag light include cable and a connector?
5 - If I were doing this I'd figure out where each of the wires ends, which I would assume are lights that have been removed, and the wires would be zip tied to the frame. Then I'd trace each wire back to where it mates into the junction/mess you've described and get rid of it.

Anyway, more info needed, but seems like a pretty simple fix. I would personally get rid of anything I didn't need especially wiring that leads to nowhere. You never know when a random hot wire in that birds nest of wiring (if you leave it there) will one day rattle loose and contact the frame and cause a short and start blowing fuses like a bull in a China shop.

I like some of the stuff at TST industries, they have a lot of cool stuff for our N400/Z400 bikes, will probably pick up a couple things. Here's their LED tag light, which is all of $16, there's a video on it too.

 

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Discussion Starter · #4 ·
jrosen007: Thanks for the reply! See my answers to your questions below:

Well, for a guy that seems to have a PhD in exhaust science and fueling (yet the only one with a handwritten dyno chart), and no fuel map..... Get the Delkevic tuned or run as is, hopefully you'll be fine, and glad your's seems to be running well and cooler; just don't bash the vast majority that get tunes and have concrete/proven dyno charts from before and after. I'm not against tunes. In my current place of residence, they are both logistically very difficult and lengthy and also much more costly in total shipped, landed, currency converted, and taxed cost, and not always needed.

Seriously though, your question above seems pretty simple question. Here's my thoughts as someone who's done a smidge of 12v stuff.
You left out too many variables, like model (assume N400, or Z400), what year? 2008 Kawasaki ZX-6R Also, did you get the full housing or just a bulb? Full housing Tail tidy or OEM tail section? OEM tail but with aftermarket LED license plate light and license plate holder Is it the wiring for license plate light only or does it mess with brake light and turn signals. License plate light only. OEM connector with 2 OEM wires that used to feed the OEM license plate light. Wire colors are "typical" for Kawasaki: Red for +ve 12 volts, Black/Yellow for ground.

1 - Do you have a multimeter? Yes Honestly this will probably help you figure out all the problems. Fluke makes great stuff, but even a moderately priced unit from Home Depot or somewhere like that will do the task. Sounds like you need to be able to measure polarity, and voltage.
2 - I would assume 99% that black is ground and red is positive. Red is +ve, Black/yellow is ground, but my predecessor owner cut the OEM wiring RIGHT BY THE OEM CONNECTOR and ran 3 sets of 2-wires, all black, to 3 different lights! Then he wrapped them all with tight heat shrink tubing! What a mess! The polarity part of the multimeter should tell you that. Perhaps take a 9V battery and touch the red to the positive and black to the negative. If that works you should be good to go. Highly doubt you'll do damage to it. LED's are very durable and highly resistant to voltage irregularities and physical abuse, which is why they're they predominant technology being used. Last way longer than incandescent and HID and draw a ton less voltage. Longer lifespan many times over means less business for light manufacturers. Most of the reason it's not everywhere is the initial cost used to be a good bit more, but that gap is narrowing, as such it's becoming more common.
3 - If it's a project bike as you say, I'm guessing you want to get rid of anything superfluous? If it were a project of mine I definitely would. As such I'd remove any of the auxiliary lights, and all of that trash cable. Already removed all the crap! Cut the heat shrink and get rid of all that crap. If I were doing a project I'd want everything done right and wouldn't want the electrical equivalent of Pandora's box hanging out in the background. Yes, if I can figure out how to do it, I'd prefer to extract the wires from the OEM (signal receiving) connector and replace the wires with standard RED and BLACK wires that go straight to the new license plate LED light. How do I extract the current wires from the 2-pole OEM connector? Don't you usuaully just have to push a paper ciip in somewhere that releases the catch that holds a wire in the connector?
4 - I'm guessing you're just talking about the LED tag light? Doesn't the OEM tag light include cable and a connector? Yes, but that connector cable is what the previous owner butchered as described above!

Anyway, more info needed, but seems like a pretty simple fix. I would personally get rid of anything I didn't need especially wiring that leads to nowhere. Already done You never know when a random hot wire in that birds nest of wiring (if you leave it there) will one day rattle loose and contact the Fram and cause a short and start blowing fuses like a bull in a China shop.

I like some of the stuff at TST industries, they have a lot of cool stuff for our N400/Z400 bikes, will probably pick up a couple things. Here's their LED tag light, which is all of $16, there's a video on it too. Got a good pre-packaged LED license plate light already that mounts to the license plate holder with 2 tiny bolts and nuts. Very nice.

Thanks for any guidance you can provide on how to extract the current wires from the OEM license plate connector and replace them. Or, should I just take the connector and its atatched 6 wires to a local computer service shop and ask them to replace those wires with 4 feet each of red wire and black wire that I can then cut to exact length and connect to the LED license plate light? I do have a supply of those "inline splice connectors that allow you to insert 2 wires and when you heat it with a heat gun, the entire connector (including a metal ring core around the 2 wires) shrinks and makes a tight and waterproof electrical + physical connector.

Jim G
 

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jrosen007: Thanks for the reply! See my answers to your questions below:



Thanks for any guidance you can provide on how to extract the current wires from the OEM license plate connector and replace them. Or, should I just take the connector and its atatched 6 wires to a local computer service shop and ask them to replace those wires with 4 feet each of red wire and black wire that I can then cut to exact length and connect to the LED license plate light? I do have a supply of those "inline splice connectors that allow you to insert 2 wires and when you heat it with a heat gun, the entire connector (including a metal ring core around the 2 wires) shrinks and makes a tight and waterproof electrical + physical connector.

Jim G
Well it sounds like you have everything under control!!!! What a yucky undertaking. Sounds like you're already there. What about ordering OEM wiring harness? Electrical shop should like a good idea, just sounded like you wanted to do everything yourself.

I'm a beginner motorcyclist, and some may roll their eyes, but I really leave all my maintenance/accessory stuff to a quality local motorcycle shop. May cost a bit more than doing it myself, but knowing a professional shop did it right and will work is like a warm security blanket. They stand behind their work, and future changes they'll already know what's going on with it. Fortunate to live between Baltimore MD and Washington DC so shops with know-how are very accessible.

Thankfully you aren't working on some old British car with wiring that my friend calls "Lucas, Prince of Darkness" (in reference to the terrible Lucas wiring).
 

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Discussion Starter · #6 ·
. . .

Thankfully you aren't working on some old British car with wiring that my friend calls "Lucas, Prince of Darkness" (in reference to the terrible Lucas wiring).
Yeah, I owned a couple of British bikes in the 1960s and 1970s with Lucas electrics. Worse even than the Amal carburetors they came with also. And of course, kickstarting only. :)

Jim G
 

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Discussion Starter · #8 ·
I made a temporary connection of the LED license plate light to the +ve and ground on the bike, and it lit up nicely! On the LED light, red is +ve and black is ground, as I had speculated.

Jim G
 

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Wow, that went off the rails quick.

Short answer is:
If you are using the correct voltage than no, you can't hurt a diode by reversing polarity.
LED = light emitting diode
Diode = one way valve for electricity
Diode doing it's job correctly =
things happen when current is flowing in the intended direction
nothing happens when current is attempting to flow in the non intended direction

Reversed polarity = trying to send electrons towards a closed valve that is designed to keep them out. No harm done.
 

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A diode is not just a perfect one way valve, it has a reverse breakdown voltage. If that's exceeded then current will flow the wrong way and the diode is likely to be damaged. Just like a one-way water valve has a maximum reverse pressure it can sustain before breaking. Even under the breakdown voltage a small leakage current still goes through the diode in reverse, the datasheet will specify what the maximum reverse leakage current is.

One of the things I've been working on at the moment is a 300 watt LED module, it's something like a 6x6" cylinder but emits as much light as 40 lightbulbs. The LEDs I'm using take 36 volts but have a reverse breakdown of iirc 50 volts, so if I connect them backwards to my 36v power supply then nothing will happen. But lower quality or specialized LEDs may have a lower reverse breakdown voltage, e.g. a 12v LED may have a reverse breakdown voltage of 5v, so if you connect that backwards then bad things will happen. It depends on how the LED is designed and its electrical characteristics.

Granted, any half decent diode (really, most every diode) will have a higher forward voltage than reverse voltage, but if you buy really cheap chinese stuff, or if the manufacturer wants to save a fraction of a cent on their materials cost, it's possible to blow a LED by hooking it up backwards.
Yes, I said that.

If you are using the correct voltage than no, you can't hurt a diode by reversing polarity.
Not sure who you are arguing with or just agreeing with me in a very strange way. IDK what's up with this forum but it seems like people would rather argue than discuss. It's a shame really.
 

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It's the same on every forum, annoys me when I find a thread about an intriguing topic and then there are pages upon pages of people talking/arguing about some minor irrelevant thing. Seems that we all fall victim to it every once in a while.
 
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