Signal Fuse Keeps Blowing Up

[Guest]

I'm new here but I thank you in advance for your time if you answer...

I recently bought a 1981 GS850G. The signal fuse keeps blowing up when I accelerate. Nothing too crazy but usually, if I reach the third speed, it blows. If I don't accelerate, or just let the bike sit, it can run for a long time without the fuse blowing.

I looked a the wires to see if anything was exposed but didn't see anything.

I don't have any added/aftermarket lighting things like warm grips.

[Steve]

It helps to know what all it powers and where it goes.

The SIGNALS fuse powers:
- turn signals (and the auto-cancel controller)
- brake lights
- horns
- oil pressure light
- neutral light

Based on your report of "third gear and up", it appears to be speed related. My guess would be a loose horn wire that is blowing back, touching the frame. Do both horns work?

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[standswithabeer]

the problem could be speed/vibration related, or engine rpm related.

i'd pick up a multimeter and measure the voltage across the battery at idle, and then at different rpm's. you could also measure the voltage at the fuse holder. the meter i have was under $11. fyi the original voltage reg on my bmw finally crapped out last summer, resulting in 15+ volts at max rpm.

[Redman]

DZ,

so so what you are saying is you have an intermittent problem (is not occurring constantly, occurs occasionally). Using a meter is not going to help in any way.

you have some idea of what conditions make it likley to reoccur, so you probably also have some idea of how often it occurs under those conditions. First check the wiring Steve mentioned (I would never disagree with Steve har har). If don’t find anything suspicious there, try disconnecting the power wires from the horns and see if go twice as long as before without Reoccurrence, then will have good idea that one of the horns was a problem.

This is is my leading suspect, although some folks have reported that it blows the main fuse.

Note: horns in stock configuration have power to them all the time (the button completes the ground), so an internal problem in the horn will short power to ground.

[Dezab]

Thanks guys for replying quickly. Really appreciate it. Turns out Steve was right, it was indeed of one the wires connected to the right horn. I can see why you won't disagree with him haha.

[Steve]

Thanks for posting the results, Dezab.

I get lucky occasionally, but the credit goes to YOU. In the words of inventor Charles F. Kettering,

A problem well-described is a problem half-solved.

It was your mention of it only happening on acceleration or elevated speed that made me think in that direction.

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