BMW K bikes (Bricks)

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1Back to top Go down    horn sounds unprompted on Mon Mar 04, 2019 3:27 pm

tinyspuds

tinyspuds
Silver member
Silver member
k
Hi,
I have an electrics problem I just canít 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 canít even be seen!
Iím pretty much at the point where Iím 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 Iím missing...
Thanks as always and in anticipation,
Stu



Last edited by tinyspuds on Mon Mar 04, 2019 4:30 pm; edited 1 time in total (Reason for editing : forgot about switch gear)


__________________________________________________
1985 BMW K100RT + Hedingham HUB and LLís.
2007 HD883 Sportster. Bobbed and bettered.
1954 Royal Enfield 350 Bullet. Original.
    

2Back to top Go down    Re: horn sounds unprompted on Mon Mar 04, 2019 4:18 pm

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
Life time member
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.


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 90,575 miles
1983 K100RS 0011175 Fricka 29,000 miles Damn K Pox
    

3Back to top Go down    Re: horn sounds unprompted on Mon Mar 04, 2019 4:28 pm

tinyspuds

tinyspuds
Silver member
Silver member
Thanks Olaf will try that tomorrow.
S


__________________________________________________
1985 BMW K100RT + Hedingham HUB and LLís.
2007 HD883 Sportster. Bobbed and bettered.
1954 Royal Enfield 350 Bullet. Original.
    

4Back to top Go down    Re: horn sounds unprompted on Mon Mar 04, 2019 4:47 pm

Dai

Dai
Life time member
Life time member
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... Razz


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

5Back to top Go down    Re: horn sounds unprompted on Mon Mar 04, 2019 4:54 pm

tinyspuds

tinyspuds
Silver member
Silver member
Cheers Dai, Iím learning that big boxes of stuff are whatís needed on this job 🤒


__________________________________________________
1985 BMW K100RT + Hedingham HUB and LLís.
2007 HD883 Sportster. Bobbed and bettered.
1954 Royal Enfield 350 Bullet. Original.
    

6Back to top Go down    Re: horn sounds unprompted on Wed Mar 06, 2019 2:08 am

tinyspuds

tinyspuds
Silver member
Silver member
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.
Donít 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†http://www.k100-forum.com/t13831-air-leak-fixing-help-needed).
Thanks again folks.
Stu


__________________________________________________
1985 BMW K100RT + Hedingham HUB and LLís.
2007 HD883 Sportster. Bobbed and bettered.
1954 Royal Enfield 350 Bullet. Original.
    

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