80 SG keeps blowing the turn signal (30amp) fuse....

[DiverRay]

Take Mikes advise and get a 20/15A breaker to go in place of the fuse! That way, when the short is no longer there, the signals/power will come back on. I did this for a headlight problem a few years ago, and it works! The other thing to try and do is look at the wire diagram and check the voltage at different locations while parked, key on. When you find a place with only 10V instead of 13V, you know what line to start looking at.

[ERM83]

Take Mikes advise and get a 20/15A breaker to go in place of the fuse! That way, when the short is no longer there, the signals/power will come back on. I did this for a headlight problem a few years ago, and it works! The other thing to try and do is look at the wire diagram and check the voltage at different locations while parked, key on. When you find a place with only 10V instead of 13V, you know what line to start looking at.

AHHH, right on! As in the locations 3phase noted???

[DiverRay]

Yes, 3phase pointed out all the locations to check, but you really need to have a picture of the wires to do it easily. If you don't have one, there should be someplace here, or a link from 3phase, that you can download one and print it on about 4 sheets of paper so its easy to read and follow.
Think of electrical as plumbing pipes, just electrons instead of water. You are looking for a leak.

[Old Red]

Try wiggling (moving) the wires with the switch on and see if you can get the fuse to blow.

[3Phase]

Color Electrical Wiring Schematic

Here's a color schematic from the forum at XS11.com.
The Forum resizes the image to fit the page here so left-click on it to open the full size 1784 x 1172 version, then Right-Click | Save As:-

XS11.com Forums > Idle Talk Forum > Links > Colored Wiring Diagrams >
80sg_81sh_wire.jpg


To print the schematic on multiple pages, load it in the free MS Paint program and set the Page Properties to 2 x 2.
Trim and tape the four pages together and you'll have something you can hold in your hand and use that doesn't need batteries or a cord.
If you mess it up, just print a new one.

Youtube instructions:-

Easily Print Large Image to Multiple Pages!! - Howtosolveit (2:02)

[bikerphil]

I have heard of the rear brake light switch shorting internally and then grounding thru the return spring where it rubs against the frame. Just another thing to check.

[ERM83]

I have heard of the rear brake light switch shorting internally and then grounding thru the return spring where it rubs against the frame. Just another thing to check.

GOOD CALL. I'm about to go get one of those automatic breakers...definitely bringing my multimeter with me when I ride to work at 4. So, ALL of those connections that 3phase mentioned should measure 13v?? Just wanted to make sure...

[Jerry]

At last year's Colorado rally a bike had a similar problem; turns out a wire was rubbing against the frame and blowing the main fuse. Do a visual inspection along all the wires where they run over or past a part of the frame. Some insulating tape fixed the problem in the short run.

[3Phase]

The voltage you get will depend on the battery but check the rear brake switch first.

With the new circuit breaker temporarily replacing the 20A SIG fuse, turn on the ignition switch and work the rear brake to see if the switch is shorted.

If the brake switch doesn't short out, measure the battery voltage and then check the voltage from any of the Brown wires to ground from the upper half of the fuse block.

The voltage at the top of the fuse block will be the battery voltage minus the voltage drop across the 30A Main fuse, ignition switch, and the harness connector.
The difference shouldn't be more than half a Volt. With the engine off, if the battery has 12.6V then the fuse block should have 12.1V.

Stay at the fuse block and check the voltage on the Brown wire after the 20A SIG fuse/breaker before it goes back into the harness.
That voltage should be the same as the voltage at the top of the fuse/breaker.

From that point, you'll have to trace the circuit and wiggle connectors.
Except for the Flasher and Turn Signal switch, the voltages should match whatever you measured after the fuse/breaker.

The voltage on the Brown/White wire from the flasher to the handlebar turn signal switch will be slightly lower after going through the relay.

The voltage on the Chocolate and Dark Green wires from the switch to the indicators/signal lamps will drop slightly again after going through the switch.

Jerry: That was Joe's bike. The Hazard Flasher was dented and the metal cover was shorting the internal relay point, blowing the Main fuse.
Joe found it when he burned his hand touching it.

[MPittma100]

Breaker

The auto reset breaker is a tool that works so well that you will look forward to the next short circuit. A Chevy dealer tech showed that to me more than 30 years ago. Someone once said "Experience is Priceless".

[dbbrian]

12v vs 6v bulbs

All that electrical talk looks interesting, but is a genuine mystery to me

I am only chiming in to say I had a similar symptom of the bulbs blowing out after a but of use, and found out the supplier had a mix of 6v and 12v bulbs in the same bin, and I was unfortunate to get the 6v ones. They look the same except the tiny print on the side.

12v bulbs solved the problem for me, thankfully.

[ERM83]

sorry about the delayed response!

It was INDEED the chocolate wire...grounding to the frame. Got'er fixed / solved! I need to make it to one of these rallies so that I can buy you guys beers (if you're drinkin' people!)

You've all helped me immensely, and it's much appreciated! Hell...I come on here and look through the archives, just because I learn so much. Thanks again!!!

Eric

[JeffH]

Sure glad to hear you found it.
Grounding out to anything is trouble. and a frustrating PITA to chase down.

Certainly would love to have you join us at XS Southeast in September at Iron Horse in Stecoah, NC. Fairly simple 325 mile run from SDF. An awesome weekend at a stellar venue. Or for a shorter 235 mile ride have lunch with the group at South Williamson over Memorial Day (Sunday Ride).

Jeff