blowng headilght fuse

I guys, I posted this on the old site a while back, and you guys seemed to help, I got it to quit blowing the fuse, ( only for awhile ) I got my bike out saterday for the last ride of the year:angry: and everything worked until I got home. When I pulled it in the garage to put it away, I seen the high beam was on, so I switched it to low, and lost everything, main fuse also. I took all the contols apart and cleaned them , put in new fuse holders, took apart the wireing term. and cleaned all them, and it still blew. should I just replace the both the contolers? Oh yeah, forgot to mention my elec. start dont work again, just once and a while if I wiggle the on-off switch. Or check for somthing else first? Thanks a bunch Craig

Pull the tank and check the wiring under there. Pay close attention to the wiring around the steering head. I don't think you should have to replace your controls, I think you would see the problem when you have them open.

savedrider, I already did all of that awhile back, and everything worked until this past sat. now I dont really know where to go from here.

Is your horn wired in? I don't have a horn right now and I had everything hooked up, hit the horn button and blew my fuse.

Probably not your problem...just tossing out ideas at this point.

Replacing the controls won't help. Fuses blow because there's too much electricity (current, really) flowing through them. Think of it like this -- if you connect a 12V light between your battery terminals, that's fine, because the 12V light provides some resistance. If you were to connect a wire straight between the contacts in the light socket, though, that's bad because instead of a light bulb providing a load, there's just a wire letting LOTS of electricity through.

In short: A fuse will blow because something is letting too much electricity through.

Now, a switch isn't designed to slow down the flow of electrity; it's designed to stop it completely (off) or let it all through (on). There's no way a toggle (on/off) switch could fail and let through TOO MUCH electricity, since its job is essentially to let it all through during operation anyways.

What you do have is clues, though -- turning the switch to let juice through to the low beam must have done something to cause problems. One side of the switch is probably always wired directly to the power supply (battery). When you turn the switch on (the low beam portion) you're providing an electrical path through the switch to whatever is past it. Chances are good that something is grounded somewhere that shouldn't be -- you just need to find out where.

Start with a meter, and with the switch turned off of low beam start testing resistance between ground and the low-beam wire coming out of the switch. If it's not at least a few ohms you have a short somewhere between the switch and whatever accessories it powers.

My experience has been that most switch problems are cause by faulty connections and dirt. (This is NOT in reference to the fuse issue). Get a wiring diagram and trace the path of voltage from the fuse area and ensure bad connections/corrosion and no dirt. That means take apart the connectors; clean them; put some diectic grease on them and then wrap a wire tie around them to snug them and get them away from where they might rub... especially on the tank.

The starter problem is MOST likely to be dirty contacts in the button OR the main connector coming OUT of the right hand switch gear which runs back along the frame is getting slightly disconnected. Based on my personal experience, these two issues account for about 95 percent of all starter related problems. The button switch CAN be cleaned... use an emory board and don't get too enthusiastic or you will remove all contact material. Dielectic grease may not be a great answer in this switch as the grease catches dirt. The connector coming from the switchgear needs to be cleaned as I noted and then a wire tie put around it or even two and then get it AWAY from the tank by tying it to the frame. When the tank moves any, it seems to want to pull that connector loose!

As far as fuse blowing... too much juice? Maybe, but my experience is that fuses blow when there is a dead short. This means that a hot wire somehow makes contact with a ground. What is a ground? ANYTHING on the bike that is metal...so if there is a bare spot ANYWHERE along the voltage path that contacts metal, the fuse will go. When in high beam, you put it on low beam and it blew! Great info as the power to the headlight is common till it splits on the secondary wiring harness that the headlight connects into. Since you didn't blow on high beam, I suggest the short will be in the secondary harness. Unplug your headlight, pull the wires that it connected to out and find where these connect to the wiring harness. OK now you have located the secondary harness.... there will be a few other unplugs but take the thing off and go look at it by itself in some bright light and look for bare spots! There will likely be one there. If you don't see one, start unwrapping tape till you get to the wires underneath and you may find wires touching where they couldn't be seen under the tape. If a hot wire and a ground touch under the tape, it works the same as grounding to the frame. Bang... fuse is gone. Concentrate your search around the hot wire to the low beams and any other wire... good luck.

wiredgeorge wrote:

As far as fuse blowing... too much juice? Maybe, but my experience is that fuses blow when there is a dead short.

Dead short == no load == WAY too much juice travelling through the circuit! There are two ways to increase the amount of juice flowing through an electrical path:

1. increase the amount in (like putting a 12V battery in a 6V system), or
2. decrease the resistance to flow (like letting electricity bypass part of the circuit).

I meant to indicate the second, since he didn't mention other problems that would indicate that too much voltage was supplied (due to a bad regulator, for instance).

Thanks for clarifying, though. It helps to combine my comments about theory with information about the actual wiring layout, which I don't know offhand.

I just wanted to make sure he wasn't replacing switches in hopes of keeping the headlight from blowing. I was trying to make the point that fuses blow because circuits are overloaded (shorts DEFINITELY count), not because switches are bad.

great information guys, thanks alot. I'll give it a try as soon as I get the time. like I said in the first post, riding season is over for me now,it 13deg. outside and snowing:blink: three days ago it was 65. But I defitantly want to get it fixed before the next time I ride it, I'll keep you posted. Thanks Craig

Chet, Thanks for taking the time to explain. I am very short on electronic theory and it didn't occur to me a short was an overload as you explained it. My experience with bike electics comes from much fumbling and bumbling and pulling of hair. I now understand things fairly well from a non-tech standpoint as far as troubleshooting and understanding the path to check in troubleshooting and such but theory escapes me... Thank goodness I majored in Liberal Arts... serves me well today to know a little about a lot instead of a lot about anything bwhahahaha

I didn't consider a bad reg/rec since he was running on high beam and it didn't fry nor did his turn signals... That type situation where voltage is high will cause problems with all bulbs...hence I didn't think about it... only a short.

buy yourself a handfull of fuses and start experimenting !pull the headlight out and remove the plug, turn your headlight switch on flip it from hi to low and see if it blows the fuse.if it still blows the fuse you know its somewhere between the switch and plug,probably a short from a wire to ground,or something inside the switch grounding out.electricity needs a ground to complete the circuit,but it uses the lightbulb or horn or other device to slow the flow of electrons in the circuit,does this make sense George?we all know what happens when you jump across the poles of a battery,but if you put a light bulb in series with the wire between the poles it just lights the bulb.the other way to blow a fuse is excessive amp draw like hooking up toomany bulbs in a circuit.say youre running some lights in a house you install 10 sixty watt bulbs in a circuit(just an example!)10bulbs x 60 watts =600 watts total divide that by 120 volts(common residential voltage) you get 5 amps which would be no problem for a 15amp circuit(14ga 15a) but if you put 30 bulbs on that circuit 30x60 =1800 watts you have put this circuit on the edge of overloading and should run a larger wire with a larger fuse(12ga 20a)these are just simple examples,i have a hard time with carbs,but im pretty good with wiring /plumbing /welding!hope this helps ,happy wrenching!

oops double fire!

Post edited by: wireguy, at: 2005/12/14 23:37