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armymutt's picture
Joined: 08/25/2008
Posts: 20

Having tackled the bigger issues with my '72 /5, I'm moving on to the horn. The horn randomly honks. With the bike at idle in the garage, there is enough vibration to make it honk. Looking at the wiring diagram, there are three wires - one black to the horn switch, one green/black to the ignition switch, and one green/black to the fuse. Since the horn is going off without the switch being pressed, that tells me there's a problem on that side of the circuit - it's also the ground. Does that sound correct to you gurus? Want to make sure I'm chasing the right gremlin before I pull any hair out.

schrader7032's picture
VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6788
Horn troubleshooting - check my logic please

You're right...the black wire is what provides a path to ground once you press the horn switch. I would try tracing that black wire from the horn to the switch to find any chafed areas that would create the random ground. It looks like the black wire goes to the headlight to make a connection and the black wire from the connection goes to the switch.

So, it looks like you're on the right track...now, finding an intermittant electrical problem is going to be fun!!

Kurt in S.A.


Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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