Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: cb550k-aaron on February 13, 2018, 07:09:19 PM
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Ok guy's,
I have a 1979 CB550k3, it came with the original handlebar controls but as they were faulty I bought new ones.
The original left side had the horn and slide over to pass which had the Light Green wire and Black. This new control only has a Light Green coming from that button and horn only.
As I'm sure you have guessed by now the horn works on the old button but not new. Anyone know how I solve it?
I'm sure it's beyond simple but Electrics aren't my strong point lol
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ah, you and me both!!
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ah, you and me both!!
Oh no :-[ Hopefully someone knows what is needed
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Sounds like you have a much earlier switchgear or U.S market one fitted. It may have different wiring to the horn. Try connecting a live "jump" wire directly from the battery positive to one terminal of the horn, then see if the horn button works.
Sent from my X6pro using Tapatalk
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That's it hairy. I was trying to think how to describe it. Honda changed the arrangement of the way the horn is wired over different models.
Presume your original switch assy aaron also had a dark blue for the headlight flash. The black was a +12v that fed either the headlight or the horn. When you pressed the button it joined the black to the light green to operate the horn. The new switch you have just connects the light green to the bike earth (through the handlebars)
I’ll call your original arrangement A and what you need with the new switch B.
A: +12v----BK----button----LG-----horn-horn-----bike earth(neg)
B: +12v----horn-horn----LG----button----bike earth(neg)
You can find the wiring diagrams on line. Honda4fun or Ash's dropbox.
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I have had this problem before. as sebeowner said its a different set up on the k3 than the earlier models. If the wiring at the horn is still original there should be two terminals on the horn, one will be the light green wire from the switch, the other should be a short wire to earth on thr horn mounting bolt.to get it working with the new switch, remove the short earth wire and replace it with a black wire you will find somewhere close, it comes out of the harness near the coils if i remember rightly, and just dangles there not attached to anything. that is a 12v live when ignition is on, so when you press the horn switch the current goes through the horn, up the light green wire and to earth via switch and handlebars.Hope this helps.
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@mickwinf
@Seabeowner
@hairygit
Thanks for clearing this up guys really appreciate it. I did actually do that last weekend (put black from around the coils to the horn) and hit the button but it didn't work. But I'm realising now that might be because the controls weren't attached to the bars yet so therefore not earthing? Is this correct?
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Certainly wont help the situation!
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Probably a stupid question. I've black Powdercoated clip ons. Would I need to take away all the paint below the switch to allow it to earth or just a little?
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probably, try running a separate earth wire to a good earth to confirm if it the problem
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Guys many thanks, problem solved as above!!