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Discussion Starter #1
I posted in the VN800 forums but cannot seem to find a good spot to post electrical issues.

Does anyone have experience switching to LED turn signals on a VN800 or similar? I bought the bike with the switch done, but incomplete. I've solved the problems with the signals I believe and have them operating properly when going left or right, but I cannot get my small dash indicator light to work. The incandescent doesn't work and LEDs wired in in a crude fashion work but leave the rear signals blinking together whether I'm going left or right.

Any help would be appreciated as I'd really like this light to work. I'm not used to manual-canceling signals at the moment.
 

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Most likely the reason it is working correctly is because the dash light does not. Not sure how technical of an answer you want so I'll try to go high-level and low-level.



High-level overview
:
Most LED turn-signals only conduct current in one direction, + to - . When you flip on the left signal for example, + battery voltage flows from the switch, to the bulb's + wire, out the bulbs' - wire, then ground.
The same is true when you use the right turn signal. Now, to power the dash lamp, it is typically wired to the left and right signal wires. This is because if we are providing +12V to the left turn signal, and the right turn signal is not being powered, the right side acts as a path-to-ground for the +12V on the indicator lamp:



Low-level
This means that the left AND right turn signal wires can both provide a + signal for the indicator lamp in the dash, and that is why many people have problems with both sides blinking at the same time. The +12V running thru indicator lamp into the opposite-side turn-signal wiring still has enough power to light-up LED bulb you put in. There is a cheap and fairly easy fix. You cut both wires running into the indicator lamp at the dash, install two 12V diodes in-line with the wires you just cut (via solder or crimps), twist them together at the other end and use that to power one of the indicator bulb wires. (Yes, you are tying two wires, the two from the turn signals, into only one wire in the indicator lamp.) The other side of the indicator lamp you connect directly to ground (a solid black wire). It's hard to explain in words, so here is a diagram I found:




You can find Diodes in lots of places. Radio Shack, Fry's Electronics stores, Best Buy, Walmart. Here's a link for wallyworld:
http://www.walmart.com/ip/Install-Bay-D1-1-Amp-Diodes-20-Pack/28969034

You will see a silver stripe wrapped around one end of the diode. That stripe will go closest to the indicator lamp for both wires.

Hope this helps some.
 

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Discussion Starter #3
This is an awesome explanation - thank you so much! I'll let you know what I come up with tinkering this weekend and will certainly ask any questions if I have them.
 

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Sure thing. Glad to help :)
 

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Discussion Starter #5
Seawolf,

I followed your directions and everything is working! I found I was unable to use the LED I got for it but the OEM florescent bulb worked as it did before, so all is well! Thank you again.
 

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If I can butt into your post. . . . :0)

I added a trunk while leaving all of the stock incandescent bulbs in place and tapping into oem wiring for the trunk lights. All lights work with no problems except the two LED taillights on the trunk.

These are two LED taillight / brake lights that work great as turn signals but do not work as taillights, there are three wires on each light. I'm assuming a diode or two is needed in the taillight wiring at the trunk?

'o5 Nomad
 

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I'm going to take a stab at it based on your description....Stop me if I get off track.

A 3-wire bulb, be it a 1157, 3457, LED, etc...is designed to have 2 brightness levels (one per wire, plus the ground wire). Assuming GND is ground ... :D then you typically have a low-level (also called running light or MINOR) and a high-level (Brake/Turn or MAJOR). This sounds like you may have tapped the (usually red) license-plate wire for the low-level, or run light. The other wire must be tapped at the green-stripe turn-signal wire for each side. So you have run/turn now and you would like to ADD a brake light signal into this.

It is possible with diodes, relays and such, but because you are using LEDs instead of incandescent bulbs it gets complex. My advice in your case is to ease the headache and buy a 3-wire to 2-wire trailer adapter to use only for the MAJOR (or the high-level) wire of your LEDs. You tap the left-turn +, brake +, and right-turn + wires for the converter. The output side is one color for left, one for right. The low-brightness (MINOR) wire for your LEDs can stay where it is at (license plate I assume) and ground is the same. This will have the LEDs come on full-bright on brake, and also flash the corresponding side as a turn signal when you activate it.

You can find an example here of the adapter:
[ame]http://www.amazon.com/Curt-Manufacturing-58240-Light-Converter/dp/B001EP0GI6[/ame]

Plenty cheap enough to avoid the headache of making a custom setup. If you do go that route, your motorcycle OEM wiring is the "car" and the trunk wiring is the "trailer".
 

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Planned use for these LED bulbs is taillight and turn signal. I have plenty of brake lights already.

The LED tail/turn lights work on 12v source: one (-) and one (+) making low power taillight and then adding the third wire to the (+) it gets bright.

Wired in the trunk one ground, one to taillight and 3rd to turn signal.

Low power taillight doesn't come on but turn signals work great and bright. I removed the taillight connections since they didn't come on anyway just in case they are screwing with the bike's electrical system.

All other lights on trunk work fine, LED light bar on each side wired only with taillight.

Another light bar on back has taillight and brake and one other dedicated brake light on trunk lid. Trunk brake lights are on brake flasher and they work great.

I really don't need the LED turn signals to be taillights but would be nice.
 

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Personally, I would tap the license plate light wiring for the low-level light on your trunk wires. The brake system low-level current may (or may not) shutoff when you apply the brake.

But first, I would test them by running a test wire straight to the positive battery post, just to make sure the low-level lighting works at all. If so, awesome, tap the red license plate bulb wire for these and you should be golden.
 
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