Blown fuse

[lamity101]

Hi: this is my first post, although I have been lurking since I bought my 1981 XS1100 SH several months ago. This site has been a big education for me on the XS1100. I have some repair experience on both the XS650 and the XS850.
It has 11,000 miles and has been running well until a few days ago. While out for a ride the other day, all of a sudden I noticed that the tach was not working. When I investigated when I got home, I saw that the "signal" fuse in the fuse panel was blown (third fuse from the left). I replaced it, got my tach back, turn signals, etc. I went for a test ride, and within a quarter mile, the fuse blew again. I have replaced the fuse several times, and it even began to blow the main fuse, which I have also replaced. If I leave the "signal" fuse out, the bike will start and run, but I have no tach, turn signals, or brake lights.
I split the left hand control on the handlebars, and everything looked ok in there. I opened the headlight, and looked at the wiring in there. Everything looks normal. I disconnected the tach, started the bike, put in the fuse, and it blew. I took out all of the turn signal bulbs, started the bike, put in a new fuse, and it blew again.
So what do I need to look for next? Am I correct that this fuse also controls the brake light? Could it be a brake light switch? A quick look at various wires and connections around the bike shows no visibile shorts, cuts, or burns. Thanks for any help. Kai

[skids]

I would suggest that you take apart the connectors to the alternator and field coil and clean them. Also, clean all of the ground connections and connections to the volt regulator/rectum frier. PS, that thing is frame grounded. The regulator is allowing too much charging and it can be caused by a bad connection. Check the voltage across the battery (or the accessory fuse terminals) with the rpms at about 4000 rpms. Hold it until the volts stabilize. Is it around 15 volts or does it climb to something like 18 or 20 v?

[Ken Talbot]

You've got a dead short somewhere in there. Keep looking for a pinched wire in the tach/signal/brake light circuits.

[wingnut]

Check the + wire on all of the turn signals. That's the one running up the center of the assy. Seen some of these get chaffed and short out to the case. Good luck

[lamity101]

still have the blown fuse problem

Hi: Thanks for the previous suggestions. I have the day off today, so I began to search for the cause of the blown fuse. I took all of the turn signals apart. One had some minor corrossion which I cleaned, and then put them all back together. STill blows the fuse. I took the fuse box loose from the bike, checked all of the connections and wiring, and everything looks ok. I have the seat off, and I have been looking at all of the wiring for obvious frayed wire, burns, etc. but so far nothing. I thought it may be the rear brake light switch, but those connections look ok, too. The brake lights work when I use the front brake. I disconnected the emergency flashing unit, and tested the fuse, but it blew. Each and every time the fuse blows as soon as I turn on the key. The battery tests at 14.5-14.8 volts at higher rpm (I don't know the exact rpm because the tach doesn't work. But I am stumped as to where the short may be. Could it be in one of the electrical components? Any further suggestions would be greatly appreciated. Thanks. lamity101/Kai

[DiverRay]

Use the VOM you have, and look for the short. I would start with the tank off, and disconnect the rear light connector, as well as all the front connectors EXCEPT the ignition switch. If it still blows, you know it's in the main harness area. If the fuse DIDN"T blow, start with the rear connection, and try again. Once you know close to where it is, the hunt should be easier.

[goldcoastguy001]

I had a similar problem, and when to similar lengths to eliminate the problem. What I found in the end was a faulty flasher can unit (the thing that goes tick tick) when i got the bike the indicators, tach and brake light didnt work and when I replaced the fused it kept blowing it. Un-plug the the flasher unit and try the fuse again I am sure this may cure your problem, if so replace it. Cheers

[randy]

lamity101;

Use your meter on OHMS setting, something low like Rx1. Zero the meter.

Disconnect the battery + lead.

Connect your meter between the battery + lead and frame ground.

Install a known good fuse in the signal and main circuits.

Turn on the key. The meter should show the short (almost 0 OHMS). Now begin twisting and wiggling the entire wiring harness starting from the fuse box forward and aft, watching the meter all the while. When you get to the frayed wire, the meter will tell you.

[lamity101]

I found the short!

Thank you everyone for your help. After reading the latest posts and ideas, I hooked up the VOM, and began going over all of the wiring again. While jiggling every wire I could find, I found the culprit. It turns out that the hot lead to the ride side horn was rubbing against the engine, and rubbed right through the insulation, and thus shorted out to the engine. I just applied a little electrical tape, rearranged the connections, and the bike is good to go. Again, all of your advice kept me looking, and eventually I found the problem. Thank you all again. lamity101/Kai

[randy]

Glad you found it.