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Blue wire bypass - headlight relay mod

36K views 57 replies 24 participants last post by  Mikeee15 
#1 · (Edited)
This guide bypasses the headlight relay, lighting your headlight when you turn the key, instead of when the engine turns.

Don't ask me about the pros/cons of this; I'm sure it will be discussed.

Video detailing the procedure at https://www.youtube.com/watch?v=C1_1MTfiJb8

On the left side of the bike remove the side cover. Unscrew the bottom screw and pull the side cover off. If you are sitting on the side of the bike, facing the side cover, pull directly toward you.

http://i16.photobucket.com/albums/b5/crowley1027/vn/IMG_20140323_061053.jpg
You will see a Palm sized black box with two connectors coming out the right side of the box. One is a smaller ten pin, one is an 8 pin.

http://i16.photobucket.com/albums/b5/crowley1027/vn/IMG_20140323_061153.jpg

Don't make the mistake I made - don't touch the ten pin connector. I pulled the blue wire from the 10 pin and moved it to the 8 pin. This is WRONG.

Pull out the 8 pin connector.

http://i16.photobucket.com/albums/b5/crowley1027/vn/IMG_20140323_061246.jpg

There is a blue wire. Pull the blue wire out of its spot (or push it from the front of the connector to reduce stress on the wires) and move it to the empty spot on the same connector.

http://i16.photobucket.com/albums/b5/crowley1027/vn/IMG_20140323_061333.jpg
http://i16.photobucket.com/albums/b5/crowley1027/vn/IMG_20140323_061559.jpg

If the spade connector pushes out as you push the connector in, just connect the plug, then push the spade connector into the empty spot to secure it.

Operation complete.
 
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#6 ·
Done :)
 
#3 ·
Thanks, much appreciated! A reasonably easy mod to do, but having pictures to look at definitely works better for me to understand what is to be done.
 
#4 ·
Well done - a great detailed write up ...with pics !

:smiley_th
 
#9 ·
Based on the diagram on page 15-36 in the manual, this bypasses the headlight fuse as well. May want to seriously consider adding an in-line fuse to protect things.
 
#10 ·
Actually if you see the schematic on page 15-50 for the junction box 8P connector, all you are doing here is removing the output from pin 8 and moving to pin 7. All that does is to take the headlight relay out of the circuit, the 10A headlight fuse (24 on the diagram) is still in the path. And you can verify that it is, by pulling the fuse after doing the repair, and seeing that the headlight will stop working.

This is a great mod, and can't beat the price !
 
#13 ·
Easy Fix for Blue wire mod cons

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.
 
#32 ·
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?[emoji223]

Sent from my SM-J700T1 using Tapatalk
 
#14 ·
Relay no fuse ?

Ty for the headlight switch info, that is a great idea and that is what I am going to do. Knew I was going to put a switch on just didnt know where.

Question, my stator is out, and I have been riding the bike all summer np, just keeping it on battery tender when not riding it. I just recently joined here and started getting familiar with the Vulcan elec system. I just found out the headlight has its own fuse, I should of thought of that way earlier, lol. So I pulled the fuse, the cops here dont care and I don't ride at night.

So, my question is, if the headlight fuse is pulled, the headlight relay is disabled and the headlight will draw 0 juice right ? Sounds like a stupid question, the headlight is off, so its draws no juice right? But I am just making sure there is no need for me to do the headlight mod if I am just going to leave the fuse pulled.

With the headlight fuse pulled and the biggest deep cycle gel battery I can fit in the hole, I bet I can ride a long time with no stator.
 
#15 ·
the headlight relay itself will still draw power, however, its a small amount.

the headlight (low beam) is 55w if I recall.. disconnecting it will increase the time for battery to die.. but.... the tail/brake lights are a big draw as well.. I think each bulb draws about 15w? and there are 2 of them. Also the turn signals and running lights (front only) draw about 10w each, more in front if flashing.

unless you have replaced them with led's, you still have a considerable amount of draw from lighting.
 
#16 ·
Hey that is a good idea if a stator goes out, pull the headlight fuse and just ride in the daytime. You can do the switch mod later if you decide to replace the stator. I would guess pulling the fuse would cut the power to everything related to the head light circuit. Will have to look at a good wiring diagram, the ones I've found so far for the vulcan are terrible, small, black and white, plus blurred out.
 
#29 ·
Pretty sure its the LAW to run a headlight on your Motorcycle here in sunny Florida.So......my Stator pooped out so tried the "Battery tender" thing,was OK but really tough to figure when that battery would die...then leave you sitting/walking.Not a enjoyable way to ride!! :frown2:
 
#17 ·
The headlight fuse also powers forward running lights and all instrument lights (spedometer lights, fuel meter light, tach lights).

I have a wiring diagram linked in my signature that has clearly labelled wires plus some design notes. Still under construction, but always improving. Check back for the most recent version when you need.
 
#18 ·
I've got a quick question regarding the blue wire mod.

I bought an OPT-7 LED headlight bulb for my 750.

I did the blue wire mod and the LED lights right up when the key goes on. No flickering at low RPMS. It seems to be running at full brightness.

The odd part is when I'm riding and coming to a stop or accelerating from a stop the HEADLIGHT indicator light flickers on and off. It goes off when I pull in the clutch.

It doesn't seem to be causing any trouble or anything to not work right but it's irritating.

Any ideas??? Thanks!
 
#23 ·
Ahhhhh, so maybe I didn't need to do the mod in the first place. This LED light was "supposed" to be plug and play. Comes with an inline driver that is supposed to stop error messages due to lower wattage.

Does anyone know if the OPT7 LED bulb needs either of these mods?

Thanks!
David
 
#24 · (Edited)
#31 · (Edited)
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!
 
#33 ·
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.
 
#34 ·
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
Ade
 
#35 ·
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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