My fuse keeps blowng

[raynalyn]

The 7 amp tailight fuse keeps blowing when installed. Anyone know what the problem might be?

[fishmeister]

A short somewhere (vague reply).             Have you done any investigating of it's wiring?

[raynalyn]

Thanks for the reply! No, I do not know where to start investigating-I have a book with the wiring diagram but can't really make sense of it. I understand the color references but the whole continuity no continuity stuff is totally foreign to me. I can tell you this. I have replaced the turn signals and they have three wires I am only using two of them could that cause a problem?

I do think the problem may have existed prior to the turn signal switch though.

[jwomack]

Thanks for the reply! No, I do not know where to start investigating-I have a book with the wiring diagram but can't really make sense of it. I understand the color references but the whole continuity no continuity stuff is totally foreign to me. I can tell you this. I have replaced the turn signals and they have three wires I am only using two of them could that cause a problem?

I do think the problem may have existed prior to the turn signal switch though.

i dont think that would make a differnce as they are on a differnt fuse...i would pull the seat off, and make sure none of the wires have been rubbing on the fram or have been pinched, also check and make sure your tale like socket is working. Try takeing the tail light bulb out and try a fuse to see if it still blows. if it does you know its not the bulb. but if it doesnt take a meter and check your voltage and whatnot.

[coffee_brake]

Thanks for the reply! No, I do not know where to start investigating-I have a book with the wiring diagram but can't really make sense of it. I understand the color references but the whole continuity no continuity stuff is totally foreign to me. I can tell you this. I have replaced the turn signals and they have three wires I am only using two of them could that cause a problem?

Yes, it can. If you have a wire hanging loose in the rear section and it touches either the frame or the rear fender or another wire, you will short it out and it will blow the fuse.

The turn signals at the front of the bike normally have three wires because the front signals always stay on in low beam, and when you signal a turn they flash on the high beam. The third wire is a ground. The rear signals, however, only come on for the turn signal. They don't normally come on otherwise, like the front ones do. Usually they have just two wires, the power and the ground.

It definately sounds like you have a short. That means you have a wire in the back that is touching to metal somewhere. You should make sure you that the third wire is not touching anything metal or another wire. You should also go through the wires for the rear signals and the tail light and make absolutely sure none of the wire has been pulled or broken, and that none of them has rubbed through the insulation and is touching either metal or another wire.

Just FYI--if  a cop sees you running with your front signals that don't stay on even when you are not signalling, they can give you a ticket. Your rears don't have to stay on but your fronts do.

Also, if you still are having troubles after all this, some motorcycles are just plain weird. I have a Yamaha that lost all the dash lights, horn, tach and tail lights and kept blowing a fuse. It was a short at the horn where it was touching the frame. So don't count out weird options, either. Anything you've touched recently, go back and check it.

[83FirstHawk]

what bike do you have?

[raynalyn]

It is an 82 CB450sc. it has always had some weirdness about it lights quit working then work but nothing like this. also there is a short in the ignition i have to kind of wiggle it to get it to come on. I'll go through and check things this week.

[ExTex]

I agree that there is a short from one of the 12 volt wires to ground.
Ususally that is from insulation that has worn away or got pinched when working on the bike.
Does the fuse blow even with the ignition turned off?
If so, then the short is between the battery and the ignition switch.
Look under the seat, under the gas tank and around the handlebars.

If you have to turn on the ignition to blow the fuse, then the problem
must be between the switch and the taillight.

Look again under the gas tank and the seat and especially between the seat and the tail light.
There is a lot of wire under there.


The 3rd wire from your read signal light mod should not be a problem IF the new lights are dual filament units and the 3rd wire just connects to the filament that you are not using.  But it never hurts to cover their connector with a piece of electrical tape.

Looking at electrical schematics does take practice.  Start at the taillight and figure out what color wires are used.
Then you can chase them back towards the front until you enter a connection and change color. 
That may happen at the fuse box or the ignition switch.

Ride safely
 

[83FirstHawk]

first place to check is the bulbs. Not often, but I have seen a light bulb burn out, and the filament leads actually fuse together in the bulb. (read short)

Next I would check the wires by the ignition switch, as you say you have to play with the switch to get the bike to run, your issues could be right there.

 ExTex has some very good pointers, follow them.

and keep your cool, wires can be frustrationg.

[ExTex]

If you want to save on fuses, get a 12 light bulb (& socket if you don't have a soldering iron)
Attach 2 wires about 6" in length to the bulb/socket.
Wire the bulb in place of the fuse that is always blowing.
The bulb should be lit until you solve the short, then it will go out.

You may have to just shove the wires into the fuse connections if it is a blade fuse (or use a blown fuse to wire to).
Or wrap the wires around the arms of the fuse holder if it is a glass fuse.

             A Short Electrical Primer
Continuity means there is a good path for the electricity to follow, which means low resistance as measured in ohms.
A short is an undesirable continuity.
An open circuit is where there is no continuity when there should be some; it is often called infinite resistance.

Wire colors are stated as the major color of the insulating material.
If there is a stripe of a different color on the wire, it is indicated as the second color as in  White/Red

When you use a multimeter to measure resistance, there is a small battery that supplies electricity to the circuit
and the meter measures the amount of electrical current is flowing.  Higher resistance may require a higher voltage battery in the meter.  Thus, some multimeter's have both a 1.5 and 9 volt battery. 
Others use just a 9 volt battery and proportion off the voltage needed at low resistance.


Ride safely.
 

[raynalyn]

Hey!
Here's an update on my electrical probs. I had my dad come over and he gave me some sage wisdom. Turns out the new signals I installed with the wires switched. Dad told me form home wiring experience that white meant ground as does green. So, I put the black with white stripe wire into the ground and signals all work. Front signals also work and run and the brake light works and the fuse is not blowing. Now My "On" lights are the only thing left so to clarify  my low beam and my tailight running doesn't work (brake light does and all filaments seem to be OK. Are there lights in the tachometer?
I am now thinking these problems which are obviously all connected could also be hooked to the "ignition switch" short I mentioned. I did notice there is a brown connector that has no wire in it in my headlight any ideas? Again it is an 1982 cb450sc.
 

[ROJ]

There will be 1 or 2 wires in the headlight bucket that do not connect to anything, that was by design for some reason, aftermarket parts maybe?? I would take your ignition switch off and take it apart to clean the contacts. I had a similar problem and doing that fixed it. I had a contact out of line which would lose contact when the switch was wiggled or the bars turned to full left lock.

[raynalyn]

Roj,

Thanks for the reply I removed the ignition switch but don't know how to get into it. There are no screws or anything should I just start popping the housing off?

[raynalyn]

crud

i popped open housing and stuff flew eveywhere. i have 2 springs and three copper pieces. is that everything or is there three springs?

[ROJ]

There is two springs, they go on the sides of the unit (you should see where) and there are 3 contacts (your copper pieces) It is pretty straightforward to put back together, just clean the contacts and make sure there is no melted areas in the plastic that alter the angle of the contacts.

[raynalyn]

I am very frustrated got the ignition switch back together and it seems to be ok. However I still have my on light issue no tail and no rear lights. Front turn signlas only for running lights. Tried to inspect the wiring seemed okay. Don't know what to do now. any ideas?

[ROJ]

Check the plug near the tail light for any corrosion, give it a good clean and try it again. So you only have running lights on the front now?? the signals don't work/flash?? The rear signal will only light up when the switch is triggered, they don't have any running lights. When you say low beam a few posts back, do you mean headlight or running lights?

[raynalyn]

All my signals work! They blink and the front ones remain on as they are supposed to. (I am assuming the real signals are not supposed to remain on). The headlight high beam works and the brake light works. Low beam and taillight are not on when the switch is on.

I am not sure of all the terminology so I may have confused you.

[Custom82Hawk]

sounds like you're getting very very close!

[raynalyn]

HELP! HELP! HELP! 

We deduced that our headlight was the bulb by jumping the current. So all that was left was the tailiight so in the process of elimination we touched the 7amp fuse with a piece of wire and put the tester on the rear bulb to see if we were getting current and POOOF Blew the main fuse. replaced fuse and now nothing nothing nothing is working. Please help what did I fry?

[raynalyn]

Okay We got the power back up to everything but the tailight again. It's strange the fuse box you bump it and everything goes off bump it again and back on. there is really nothing too it but dog ears what does this mean? Is it dirty? I sprayed wd40 on it. Anyway put a tester across the tailight fuse and it lights so going to try to follow advice of leaving tester on and when it goes off we found the glitch. Where should I start though in the headlight or the tail light? the wiring diagrams shows it going clear into the headlight and then back to the tail seems like alot of places for problems! Any ideas?

[ROJ]

Ok, first off it sounds like your fuse box might be on the way out, see if you can source a used one in good condition to  keep in case yours goes. If you take out the tail light bulb, are you getting any power through the low beam (running light) wires?? or just the brake wires. If you are getting power, then work backwards to the plug, check, double check, and triple check to make sure the connections are clean and that none of the wires are bare.

[raynalyn]

did the fuse thing with a voltmeter instead of a 12 volt bulb. Seems that unhooking the main starter button kill switch connector fixes the short. made up of 4 or five wire. also the brown and blue wire specifically seems to be the one but noapparent problems with it. the wire runs to my electric starter button. Also noticed that when I hiit the electric start the voltmeter goes off. Could it be the starter button?

[83FirstHawk]

Ok here is what I gather from the wiring diagram from an '83 550/650.
    I know its a different bike, but I dont have your wiring diagram.  Might be the same, Might not.
IF THIS LOOKS NOTHING LIKE WHAT YOU SEE ON YOUR BIKES WIRING THEN THIS DOES NOT APPLY
Here is what I see:
    The headlight is on a different fuse than the tail lights altogether, If your High Beam works, the only difference for the low beam is the switch for the high/low beam. I would check the bulb socket for the headlight. If the colors are the same, on the headlight socket, Blue is HIGH, White is LOW, and Green is GROUND, check that you have 12v on those wires. if so then its the headlight bulb.

Now for the tail light, on the 1983 models, the tail light, instrument cluster gage lights, and the front running lights (turn signals lit dimly) are on the same fuse.  From the tail light, liscence plate light, and broken wire warning unit (if you have one) to the fuse box, ignition switch, the wire is BROWN. From the ignition switch to the guages and turn signal switch the wire is BROWN/WHITE. From the turn signal switch to the front LEFT running light it is ORANGE/White, and from the turn signal switch to the front RIGHT running light the wire is LIGHT BLUE/White.

Hope this helps.

[ROJ]

When you hit the start button it is supposed to interrupt all other electrical (i.e. lights) so they are not drawing power from the battery at the same time as the starter. Motorcycle batteries don't have the juice to do both at the same time. So I would clean up the connectors around the kill switch and see if that helps any. 83firsthawk is right, taillight wire is brown and that is pretty easy to follow.