Blue wire bypass - headlight relay mod - Page 4 - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Where does this wire go?
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post #31 of 38 (permalink) Old 06-17-2018, 10:32 PM
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Got the RLU bypass done a few days back. It solved the flicker-y Headlight light on the dash! And, after the blue wire mod, the light comes on when the key turns, which is very nice. Also, the LED has a much better spread and is just brighter at night.

I also replaced my rear brake/running light with two LEDs. Changing these and the headlight to LED has really reduced the dim of lights at idle while the brake light is being activated like at a stop light.

There is a barely noticeable flicker with the new LEDs only at idle, but it's very minimal and I don't think I'm going to worry about it.

Thanks for the help guys!

Last edited by magicdave2; 06-17-2018 at 10:43 PM.
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post #32 of 38 (permalink) Old 06-05-2019, 07:11 PM
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Originally Posted by Vulcan Rules View Post
For the Blue wire mod cons - Headlight stays on when key is turned on, which obviously takes power away from starting.

What I did was splice in a good quality mini toggle switch between the ground headlight wire inside the headlight cover, drilled a small hole in the lower head light cover to run the mini toggle switch through. The switch can then be off for starting, then easily turned on when warmed up and ready to ride. Very inexpensive easy fix to get full power for starting, after doing the Mod.
Can you explain this with wire colors and step by step instructions I did the blue wire mod and would like to install a switch?

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post #33 of 38 (permalink) Old 06-06-2019, 10:58 AM
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The ground wires on this bike are black w/yellow stripe. Ground switching is the best way to go when it's possible, no chance of it shorting out. My voltmeter is switched on the ground side.

If you get the AGM battery, the headlight staying on should be no problem.

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post #34 of 38 (permalink) Old 10-25-2019, 04:36 PM
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Hi Guys (and Gals) 👋 I’m in England and have just joined. I’ve recently replaced my stator and rectifier and suddenly have the dreaded “Headlight not working” scenario. I think a mod was done to the bike before I got it (late last year) as the headlight used to come on with the ignition switch. I can’t see the “blue wire mod” at the fuse box end though and the connector where one would expect the power to come onward from the fuse is empty, so where does it go and is it really protecting the headlight circuit????☹️
My question is - is the headlight relay replaceable? And if so how? As this seems to me to be the obvious solution...
I’m no electrician, so please excuse me if the answer is staring me in the face!
Safe journeys all
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post #35 of 38 (permalink) Old 10-26-2019, 04:21 AM
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Hi Ade,

After the standard blue wire mod, the headlight fuse will be unused, and the taillight fuse will provide power to the headlight.
Replacing the headlight relay requires desoldering the old component and soldering a new one back onto the circuit board. It is not a horrible procedure if you're comfortable soldering, if you can find the right component to buy.

Regarding the rest of your problems, I suggest starting a new thread specific to resolving the problems on your bike since it sounds like there's going to be a lot of investigation involved and we should try to keep the post count low on this "how-to" thread to keep things clear for future readers of the blue wire mod.

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post #36 of 38 (permalink) Old 10-26-2019, 10:26 AM
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What is the “reserve” lighting unit for?
And how do I check it’s working please?
As still baffled as to why I have power going to the blue wire from the headlight fuse, but no power at the light... 🤔
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post #37 of 38 (permalink) Old 10-26-2019, 10:29 AM
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Thanks for your help Thorn btw 👍😁
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post #38 of 38 (permalink) Old 10-26-2019, 11:01 AM
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Originally Posted by BannedAde View Post
What is the “reserve” lighting unit for?
And how do I check it’s working please?
As still baffled as to why I have power going to the blue wire from the headlight fuse, but no power at the light... 🤔
The reserve lighting unit will automatically switch from low beam to high beam if it detects a filament failure. Without you having to toggle the headlight switch. If there is any intention on going to an LED headlight, it could cause flickering because the LED bulbs do not consume as much power as the stock incandescent bulbs. It can be bypassed very simply by using a jumper across 2 pins on the connector. That mod can be easily found on here (with pics) by running a search on “RLU bypass”
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