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Hi,
I have an electrics problem I just can’t get my head around. Please work your magic.
Symptoms:
-About 100 miles ago (driving pretty much in a straight line) my horns gave a short burst without being asked.
-Over the next few days this happened a few more times.
-Yesterday this happened almost every time I turned the bars, until eventually the horn sounded constantly regardless of handlebar position until the ignition was turned off.
Investigation - bike cold:
-Replicated the short burst and continuous problem by moving the bars
-Very technically wiggled the horn wires, no reaction
-Fairing off, headlamp, running light, indicators, horns disconnected, using circuit tester on live could intermittently replicate problem by moving bars (no response on ground) - relay activating
-No trapped wires, No chaffing, No real tight spots
-Yanked every wire in front of headstock, no response
-Handlebar switchgear off inspected and contact sprayed
-Tank off, no visible issues, no response to more very technical wire wriggling
-All relays seated firmly, uncapped, contact cleaner, replaced and re seated.
At the weekend I renewed rear shock, changed final drive fluid, lubed splines and sorted an ongoing problem with lean in adjustment. Excited to test it all but frustrated by a force that can’t even be seen!
I’m pretty much at the point where I’m considering putting golf tees in the fuel pipes - as apparently that solves everything.
Used to the idea that Ks do stuff a bit special - so please tell me what I’m missing...
Thanks as always and in anticipation,
Stu

Swap horn and fuel relay inside the relay box...same relays, interchangeable. May possibly be faulty relay.....? Does sound more like damaged wiring issue but Ks are strange...the fault may not be in switch wiring but in something else activating the relay.

Thanks Olaf will try that tomorrow.
S

If it turns out to be a relay problem, be aware that BMW use DIN A standard relays but the ones in your local corner shop are DIN B. The difference is that pins 37 and 86 are swapped round. If you can't be assed to push the terminals out to take a DIN B relay, PM me because I've got half-a-boxfull of DIN A ones.

It would have been a boxfull but it's a big box...

Cheers Dai, I’m learning that big boxes of stuff are what’s needed on this job 🤒

Replaced fairing and tank plus all electrical connections with the ignition on - not a sound. 30 mile run, horn behaving normally. Everything I touched got contact cleaned.
Don’t really have anywhere to go from here, but if the problem starts again I will try the relay swap. Spare on order later today, along with all the rubber I need to future proof the fuel/air components (Found this really useful shopping list https://www.k100-forum.com/t13831-air-leak-fixing-help-needed).
Thanks again folks.
Stu