BMW K bikes (Bricks)

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

tinyspuds

tinyspuds
Life time member
Life time member
k
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



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 LL’s. VIN 0028106. (Not blind to the irony of an April 1 production date).
1986 K100RS in boxes. VIN 0141918.
1954 Royal Enfield 350 Bullet. Original.
    

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

92KK 84WW Olaf

avatar
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 Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 37,190 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 39.885miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

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

tinyspuds

tinyspuds
Life time member
Life time member
Thanks Olaf will try that tomorrow.
S


__________________________________________________
1985 BMW K100RT + Hedingham HUB and LL’s. VIN 0028106. (Not blind to the irony of an April 1 production date).
1986 K100RS in boxes. VIN 0141918.
1954 Royal Enfield 350 Bullet. Original.
    

4Back to top Go down   horn sounds unprompted Empty Re: horn sounds unprompted 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


__________________________________________________
1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

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

tinyspuds

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


__________________________________________________
1985 BMW K100RT + Hedingham HUB and LL’s. VIN 0028106. (Not blind to the irony of an April 1 production date).
1986 K100RS in boxes. VIN 0141918.
1954 Royal Enfield 350 Bullet. Original.
    

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

tinyspuds

tinyspuds
Life time member
Life time 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.
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


__________________________________________________
1985 BMW K100RT + Hedingham HUB and LL’s. VIN 0028106. (Not blind to the irony of an April 1 production date).
1986 K100RS in boxes. VIN 0141918.
1954 Royal Enfield 350 Bullet. Original.
    

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