Electrical woes - short problems

Hey guys,

For my '82 KZ750N Spectre: I recently rewired the fuse box with in-line fuse holders that take the newer type fuses. This was in response to a blown taillight 10A glass fuse that was impossible to find anywhere. When the fuse blew last week, I thought it was strange that the whole bike shut off but didn't think anything of it. Now, after I rewired the bike with the in-line fuse holder and new spade-type fuses, I notice the tail light it out. After getting under the bike, I jiggled the wires and the tail lights pop back on, so I figure it's just a loose connection and push all the connectors back in. Problem solved?

Nope. Got about half a block down the road and the whole bike shuts down again. But it's not the main fuse that blew, it's the taillight fuse that blew again. I can understand if I need to rewire the back wiring harness assembly (to the rear turn signal and brake/running lights), but why the heck would a blown taillight assy fuse make the whole bike shut down? I would think that only the 30A main fuse blowing would cause this.

Thanks!

Not sure why you chose in-line fuse holders vrs a fuse box. There are lots of different fuse boxes for sale that take the ATO fuses. You could even do the Little mini ones.
Your right, blowing a tail light fuse, should not kill the bike. Maybe you got something crossed during the rewire?
That rear harness can get pinched under the seat pretty easy. It can be removed and inspected for any bare spots, or you could make up a new section.

I know, not sure why the bike dies. Not the rewire job though, it happened before I did the rewire, too. I already ordered a fuse box, the in-line holders were just a temporary fix (I didn't want to not ride for 2 weeks).

I undid all the electrical tape that was back there, it didn't look like any was frayed at all. Besides the loose connection, I don't know why the fuse would keep blowing.

I'm debating on taking it somewhere if I can't find a glaring problem. I can do the basics myself but tracking down an electrical problem may be more involved than I can handle.

OK so I got a little more time to check out the problem today (hard to put aside time when you work 50-60 hours a week lol). My mistake, it wasn't the 3rd fuse down that blew, it was the 2nd fuse down....aka the headlight fuse (NOT taillight, like I had originally claimed). Sorry about that!

So I get the bike taken apart, and a guy who's going to WyoTech down here helped me take a look at it. The fuse was running pretty warm, and just as a baseline we felt the other fuses and they were cool to the touch. When I turned the turn signal on, POP 2 seconds later the bike shuts down - fuse blown. So at least I narrowed down the problem to that.

We followed the problem up the wire and found that the 2 white/red leads coming out of the turn signal relay were pretty hot even with no signal. With the bike off, the fuse wouldn't blow, but with the bike running, they did. There's alot of crud on them as you can see in the picture below, so I'm hoping that tomorrow I can cut them off at the ends, crimp on some new connectors, plug them back in, wrap 'er up with some e-tape and be done with this episode.

Do you think that this is what the problem is being caused by, or am I missing something bigger here?

Thanks!

phillyman2633 wrote: OK so I got a little more time to check out the problem today (hard to put aside time when you work 50-60 hours a week lol). My mistake, it wasn't the 3rd fuse down that blew, it was the 2nd fuse down....aka the headlight fuse (NOT taillight, like I had originally claimed). Sorry about that!

So I get the bike taken apart, and a guy who's going to WyoTech down here helped me take a look at it. The fuse was running pretty warm, and just as a baseline we felt the other fuses and they were cool to the touch. When I turned the turn signal on, POP 2 seconds later the bike shuts down - fuse blown. So at least I narrowed down the problem to that.

We followed the problem up the wire and found that the 2 white/red leads coming out of the turn signal relay were pretty hot even with no signal. With the bike off, the fuse wouldn't blow, but with the bike running, they did. There's alot of crud on them as you can see in the picture below, so I'm hoping that tomorrow I can cut them off at the ends, crimp on some new connectors, plug them back in, wrap 'er up with some e-tape and be done with this episode.

Do you think that this is what the problem is being caused by, or am I missing something bigger here?

Thanks!

The picture is of the Positive wires, one from the R/R and the other the feed to the fuse box. They connect to the starter post, which is the battery cable. Those do look heat damaged, from a poor connection.
So having the head light fuse blow, then the bike die. Look at your wiring diagram and see if that fuse also feeds the ignition circuit. Might very well. So you still have a short. I'd say if it blew right after turning on the signals. Pull all the turn bulbs, then try it. See if it still blows when you hit the turn. If so, does your bike have wiring that goes through the handle bars? Or is it routed outside of the bars? If inside the short is very likely in there. If not then could be in next to the steering head along the frame, as you turn the wires can pinch. Or maybe inside the head light bucket. Thats the other common place as the wiring is always tight in there, not much room.

Motor Head wrote: The picture is of the Positive wires, one from the R/R and the other the feed to the fuse box. They connect to the starter post, which is the battery cable. Those do look heat damaged, from a poor connection.
So having the head light fuse blow, then the bike die. Look at your wiring diagram and see if that fuse also feeds the ignition circuit. Might very well. So you still have a short. I'd say if it blew right after turning on the signals. Pull all the turn bulbs, then try it. See if it still blows when you hit the turn. If so, does your bike have wiring that goes through the handle bars? Or is it routed outside of the bars? If inside the short is very likely in there. If not then could be in next to the steering head along the frame, as you turn the wires can pinch. Or maybe inside the head light bucket. Thats the other common place as the wiring is always tight in there, not much room.

I looked at the wiring earlier, it looks like the harness is outside the handlebars and runs under the fuel tank. As for checking to see if the fuse still blows with the bulbs out, I'll try tomorrow and update. Here's a question...should the bike be quitting with the headlamp fuse blowing? Or is it a problem with a bad ground? I couldn't find an exact wiring diagram (KZ750N1) but from what I can tell, this looks exactly like mine wire for wire:

www.flickr.com/photos/justinbelshe/3023990483/

On the diagram you posted the link to. Which of the fuses is the one blowing? Left one is the Main Fuse. So from there, next one over or ?

Motor Head wrote: On the diagram you posted the link to. Which of the fuses is the one blowing? Left one is the Main Fuse. So from there, next one over or ?

Left-to-right correlates to top-to-bottom on my panel, so on this diagram the 2nd from the left is the one that is blowing

phillyman2633 wrote: ... couldn't find an exact wiring diagram (KZ750N1)....

For the wiring diagram in KZr's FILEBASE --
Click here > www.kzrider.com/filebase/doc_download/285-z750n1

Good Fortune!

That fuse powers the Marker/ running lights on the front. Which means you should have dual filament bulbs in both front signals. It also powers the warning lamps in your cluster. So you could have a short at the bulb sockets, turn, or maybe at the cluster wiring. That diagram doesn't show the switch contacts, but that wire also goes to the ignition switch. Without a contact grid on the diagram, its a guess to know where it connects at key on. You could find out with meter. Or maybe there is another diagram out there with the switch contacts.
Its cut off of the one in file base that Patton posted also. No switch contact chart.
Looking at it again. I belive the power comes into the rest of the fuse box on that fuse/ circuit. So that is why the bike dies when it blows.
Power first goes through from the battery, main fuse, up to the ignition switch, back down to that second fuse that has blow on you, then making the other fuses hot. So when it blows nothing has power. Probably take a bit of inspection to see where the short might be.
The third fuse over, with the brown wire leading out of it is for the ignition. But it receives power from the one that blows.
You could try running the bike with just those first three fuses and see if it runs without blowing. The put in the next one. Try again. And so on. The you would at least pin down which circuit might be the issue.

In my above picture, is the boot directly to the right of my hand (where the 2 white/red wires are leading out of) the ground wire?

phillyman2633 wrote: In my above picture, is the boot directly to the right of my hand (where the 2 white/red wires are leading out of) the ground wire?

No. Ground wire color is Black with a Yellow strip.
Like I said those wires are Power. One to the battery cable post at the solenoid from the R/R, which charges the battery, and the other into the fuse panel to feed power to the bikes electrical.