I'm not sure where to start looking for this problem. I hope someone here has some hints and tips to get me started.

The bike was working fine. I was riding at about 125km/h when the tachometer and speedometer suddenly dropped to zero. The bike kept running but there were no lights in the dash and no turn signals. The headlight and tail light both still worked, as did the starter and horn.

I found a blown 7.5A fuse and replaced it and everything came back up. I left the bike for 30 minutes and turned the ignition switch to on when I returned. I noticed no lights in the dash and tested the turn signals. They weren't working again. I had not started the bike yet, just turned the key to on. Not wanting to waste another fuse and having a ferry to catch I drove home with no other problems aside from some nervous moments around police cars, not knowing how fast I was going :-)

Any ideas where I might start looking? I can only assume that something is shorting out since the fuse blew without the bike even running. Also, I found that the brake light was constantly on. Am I wrong in assuming that this shouldn't have anything to do with the fuse blowing? ...it's on a different circuit and that fuse was intact.


Thanks for any help.


...Michelle
www.scrabblebiker.com

I would hazard a guess that you are not wrong; the brake light constantly on may be caused by a sticky switch - one of the two for the front and back.

As for your fuze problem, your description of the symptoms points toward the ignition circuit (before pressing the start button) including whatever else is on that fuze (you don't say if you have a wiring diagram).
Could there be a short in the ignition circuit??

I hope this helps - you seem to have a methodical thought process to date

__________________
Dave

I had a very similar problem with my 2002 F650GS single.
Mine was caused by a broken wire up near the bars.
Can't tell you which one I'm afraid as took it to a man who knew what he was doing.
Good luck.

Get a wiring diagram and check the circuit protected by that 7.5A fuse; doubt it is the ignition circuit or the bike would not run.

The fuse can blow as soon as the ignition is switched on so doubt it blew while the bike was off - I suspect all the fused circuits are switched power i.e. only on when the ignition is on - except for the main fuse which will be bigger than 7.5A.

Usual locations are places where the loom rests against part of the frame and rubs through. You can use a multimeter to check approximately where the short is by checking resistance between various connectors/components and ground (will be zero if there is a short in that part of the circuit), although you can often see where the short is with a thoughtful search of the loom.

The circuit to check is the instrument light-indicator circuit which is switched. You are correct that the brake light being constantly on will not be connected to this problem as otherwise the fuse for that circuit would also be blown.

Thanks for all the replies. I have since found the problem and fixed it.

First of all, the brake light was NOT on all the time. The tail light was just brighter than I remember it being and the brake light was simply not working at all due to a blown filament in the tail light bulb.

Upon replacing the bulb, the brake light still didn't work. That's when I discovered that the wires going to the rear brake pedal light switch had come loose from the clips on the frame and had gotten caught in the chain at some point. One of the two wires was ripped apart. I spliced the wire with a little handy dandy splicing tube and taped it all up with electrician's tape. Lo and behold, the brake light was working again. It's now been 3 days and the fuse hasn't blown again.

I can only guess that the short from the wire ripping caused the filament to blow. Even though it's a completely different circuit it seems that maybe the torn wire was shorting against the frame and causing the other problem? All I can say is that after fixing the wire I'm no longer blowing the fuse for the turn signals and dash lights.


...Michelle
www.scrabblebiker.com

Michelle,
Sounds like a happy ending and thanks for reporting back and providing the final piece of the puzzle - funny stuff that electricity, but the connections and broken wires can play tricks and cause strange symptoms.
Bulbs are a bit like fuzes; very thin wires in the circuit.

Doc,
"doubt it is the ignition circuit or the bike would not run" - Yea, I wasn't thinking too straight there!

__________________
Dave

Good to hear you found your solution.

While on the subject we had the same problem with the same fuse and loss of power to the dashboard/speedo/rev counter.

As it turned out, a connection had come loose within one of the indicators and was shorting itself against the case / bulb.

This happened soon after we had taken the side panels off to check the battery and airbox and in removing the indicator we obviously loosened the connection which subsequently shorted the fuse se as soon as the bike started up.

. . thats my 2 pence worth, time for a .

Chris & Chloe
BUENOS AIRES to VANCOUVER | Chris, Chloe & two motorbikes across South, Central & North America

New to this site. Found this thread while troubleshooting. Thanks for posting.

A bunch of things happened at once. My Touratech chain guard was torn off the bike, chewed up by the chain and chucked. Then the battery died. Then the 7.5 amp mini fuse kept blowing after putting in new battery. We changed back to a 2013 BMW G650GS plastic chain guard, a perfect match for the F650GS and the best solution at about $25. The other option was modifying the original chain guard by removing the mud flap and cutting the chain guard. Sadly, not very happy with the Touratech after a rock clipped it and broke a link on my chain while I was on the Dalton Hwy. in 2008.

When it first happened, after the battery install, the dash instruments died, turn signals and brake light. The headlamp and tail light worked. We found your post and went back through, checking the chain for potential wiring snags and the turn signals. The hot lead had come off on the right turn signal and was shorting out against the ground lead. We'll see what happens tomorrow on the test ride.

My G650GS 2015 30,000km blew the 7.5A fuse which took out the instruments, stop light and indicators. I eventually found the short. Follow the wiring loom down about 100mm from the fuse box toward the front of the bike. At a junction with a smaller wire that joins the loom here, it is held to the frame with a cable tie. Well, it was on mine. This is where mine was shorting to the frame. I won't be replacing the cable tie at that spot. Check other parts of the loom as there were spots wearing through on my bike. Also check the bracket that holds the rear shock preload adjuster to the frame. Mine had a fatigue break. BMW told me it's a known issue.