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Discussion Starter · #1 ·
So stupid me I left my key in the ignition a week back and killed the battery. It is a brand new sealed battery so no problem I recharge it and the bike runs fine. When I tried cranking it up I noticed that the head light didn't work, This I thought was because the battery wasn't fully charged and just needed some more time. So i lived with it for a 30 minute ride thinking while I was riding the generator would charge up the battery and get the light to come on but still no light. I then fiddled with the light thinking maybe the bulb blew since it was on for the extended time while the battery died. Then I checked the fuses as well thinking maybe a short of some sort but nothing there as well. I crank it up the next time and the head light does come on so I think i figured out the problem. This morning I try and go to work and see that the light is not on once again, I checked the connections to the light in the headlight to see if something was loose and checked the fuses but none of this seems to be the problem. I have no problems with any other lights so i am scratching my head. On the console I am not getting the light saying the headlight is on nor the light for the brights when I flip the switch. I am in no way a mechanic or electrician so I am lost with this one. Any ideas guys.
 

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Sparky!!!
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8,709 Posts
sounds like a bad connection inside the Reserve Lighting Unit, or a sticking Headlight relay inside the Junction Box. Next time you don't have headlights, check that the blue wires in the JB have power. If no power present then its the JB, if there is power then its the RLU.
 

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Calif Rider
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Try reading the the VN 750 threads on headlights problems in the search. In the search type headlights problems and you will get alot of info on what causes the headlight to stop working and how to check it out.
 

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Banned
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Are the rest of your electronics working right? Oil warning light with key in ON position before starting? Brake lights working?
 

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Unfortunately, one of the Vulcan 750s many features is a complicated headlight system. It has the reserve lighting system, which automatically switches filaments if one burns out, and activates a light on the instrument panel. It also has a relay that won't let the light come on until the engine fires. You will just have to take a multimeter and start tracing things down. If I had problems with the lighting system, I would scrap it, eliminate both the reserve lighting unit and the relay that prevents the light from coming on until the engine fires, and install a manual switch so I could turn the headlight off while starting. At least it is electrical, and not electronic, so some time with a multimeter should find the problem. I personally believe all motorcycles should have an "off" switch for the lights anyway. I see "always on" headlights the same way I see sidestand and clutch switches, just more unneeded government mandated safety bullcrap.

Oh, and BTW, even though you have a nice new sealed battery, you did do some damage to it by letting it go completely dead. It will no longer have the capacity it had to begin with, and the more times you let it go dead, the worse it will get. I have had the life of many bike batteries shortened by allowing them to go dead, so I finally gave in and got a Battery Tender Jr. for every one of my bike batteries. Jerry.
 

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Discussion Starter · #6 ·
on the console the other lights seem to be fine I can see the oil light when I turn the ignition on as well as neutral if it is engaged. I am thinking I am in need of a replacement reserve lighting unit or a switch to turn the light on and off.
 

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I have to agree with slim here, the JB does seem the most likely culprit, especially if neither the high or low beam will come on, no matter which position the high/low switch is in. I have had 3 headlight bulbs burn out on my '02 with 44,000 miles (one filament only) and each time, the reserve lighting unit switched filaments, and the light came on on the panel. But, had this happened at night, I would have immediately switched from one beam to the other manually. I have had that happen to me a couple of times on other bikes. That's why I see the reserve lighting unit as unnecessary. Just be glad the Vulcan doesn't have self canceling turn signals. What a can of worms those things are, and they don't work right even when they are working as designed. Works fine on cars though, but it is about 10 times simpler. Jerry.
 

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IJust be glad the Vulcan doesn't have self canceling turn signals. What a can of worms those things are, and they don't work right even when they are working as designed.Jerry.
Uh, hate to break this to you, but the first few years do have self cancelling turn signals.
 

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The Professor
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My 85' has self canceling signals with all the original components and is still working as it was designed to. :beerchug:
 

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I didn't know the Vulcan ever had them. I'm sure glad mine doesn't. If it had, they would have been redesigned right away. I had a Yamaha Virago 750 that had them and what a nightmare. Either they would turn off before you got to the turn, or they would keep flashing long after you made the turn. I finally rigged them so they worked as normal turn signals. Jerry.
 

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Linkmeister Supreme
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sounds like a bad connection inside the Reserve Lighting Unit, or a sticking Headlight relay inside the Junction Box. Next time you don't have headlights, check that the blue wires in the JB have power. If no power present then its the JB, if there is power then its the RLU.
Slim, IIRC you can take one of those blue wires and pull it off a connector and plug it onto an empty connector next to it that is powered when ever the key is on. It can get your lights back on quickly to get you back home in the dark. Sorry, I just don`t remember the specific wire or connector.

I am sure you know this and can spell out the particular wire and connector location to try this solution.
 

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Sparky!!!
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yes you just move the blue wire into the empty slot... doesn't matter which one, they both o to the headlight eventually. but then you bypass the relay and can cook the wire harness if something should fail...hmm wonder how I know this one...
 

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The Professor
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yes you just move the blue wire into the empty slot... doesn't matter which one, they both o to the headlight eventually. but then you bypass the relay and can cook the wire harness if something should fail...hmm wonder how I know this one...
Bypassing the HL relay will not possibly "fry" your harness since it is still a fused circuit. The only difference is the HL will come on as soon as you turn your key.

If you decide to alter your wire harness for aftermarket electrical devices and don't do your haome work then 'YES" you can fry the harness. It's usually something stipid like one copper strand hits a ground or you use a fuse that's larger than the "load" the system was designed for.
 

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Sparky!!!
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well my harness is shot... and the only thing i did to it was add an aftermarket headlight, and bypass the relay... to wire in the new headlight, i ran a wire streight from the spare slot on the JB to the headlight, and grounded the headlight out through the OEM ground wire.
 

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Hey slim. I moved the blue wire on the JB to the empty slot when I got my bike last year. Previous owner put a switch on there but then the highbeams would not work. When I moved the blue wire to the empty slot, headlights worked fine. As Lance said, the only difference I can see if that the headlights turn on when the key is in the on position. I just keep my battery charged well and she cranks up every time without issues.
 

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Discussion Starter · #17 ·
So i went out and bought a new (to me at least) junction box thinking that this is the problem and I installed it today. The headlight is still not working so I am thinking that it must be the reserve headlight unit. With the new junction box all the lights work, blinkers blink but the headlight is still not working. The lights on the dash do not show up for the headlight and when I flip the high beams on that light does not come on as well. Would this be the reserve headlight unit not letting it work or is it something else? I do not own a multi-meter so I am thinking that I might have to go out and buy one to track down this problem. Sorry I am so amateur at this I do like learning about all these things at least.

One other thing, How do you take the wires out of the plastic around them at the junction box? I was hoping I could just switch the blue wire with the empty spot to at least have a headlight till i get this problem sorted out. I have tried pushing the wire out with a flat head but no luck, I am afraid I will bugger up the connection if I mess with it to much.
 

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Discussion Starter · #19 ·
no test light as well, Its something on the things to get when in home depot but just somehow forget about it.
 

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Sparky!!!
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Get a test light at Wal mart, you can even get a decent Multi Meter for cheap at Wal-Mart. but in order to help you fix your bike, you need to have the proper tools.

Every one needs to own a Test Light at a bare minimum for testing electrical problems. A test light has about a thousand different uses depending upon what you are testing and how you hook it up for testing. A Multimeter is also a good thing to have, but make sure you get a digital one instead of analog. But until you get the right tools, its going to be hard for us to help you figure out what is going on.
 
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