Hi all! Just bought a 2012 Road King. It's my first Harley, and I love it!
The previous owner installed a bunch of extras. Unfortunately, he didn't do a very good job on the electrical part of the job. I've been working on cars, motorcycles, airplanes, etc. for 35 years and sloppy work bugs me, so I'm redoing the sloppy wiring.
Long story short, I removed an air horn, that I didn't care for, from the left side of the engine. After removial, the factory horn connect wires were there, but so was a black ground wire that is factory bolted to the rear cylinder head. It has a small spade connector like the horn wires. I can't find where this wire goes. I looked on the horn bracket, but didn't see a place where it might connect. Perhaps I'm blind. Does this ground attach to the horn, or go somewhere else? This Harley newbie would appreciate any help!

 

duplicate.....

 

I can't say that I've ever seen a ground wire bolted to a cylinder head. Can you take a picture?

I belive there are two terminals that go to the horn. Here's what my manual says:

 

depending on where or if the PO used a relay ( should have) for the air horn- the extra ground could be for that.

when I use an air horn, I usually wire in the relay near the battery...I find that an easy location.

the H-D service manual has really good wiring diagrams and thankfully H-D has used pretty much the same colour coding since the early 80's for many of the circuits.
So once you get conversant you can apply that along various model years- however I can never remember the left/ right of the turns signal wires which are violet/brown.

horn hot is yel/blk.
ground is black

strongly suggest that you not solder any joints on the wiring you are de-coding...soldered wires tend to fracture right where the tinning ends due to vibration.
Crimps are better- and if you feel the need you can slide shrink tubing over the crimp terminals, extra points for die-electric grease

mike

 

You can use this extra wire to check your starter motor ground connection (maybe once a year).

 

After closer inspection, the wire is bolted to the horn bracket on the rear cylinder head. I found the two horn wires and connected them to the new horn. I'm assuming the remaining black wire is a factory due to the fact that it has a connector that is identical to the horn connectors and is the the same quality. Perhaps it isn't. I'm too new to Harley's to know if this wire belongs. I've only had the bike a week, but I'll get a service manual this week.
The air horn I removed had its own wiring to a relay under the seat. I removed all that.
Here's some pics.
Thanks!

 

Hey that's cool! Invisible spark plugs! What will they think of next?

 

The obsoleted VOES ground wire was attached like that.

leads me to think that an older experienced tech did that install.

anyway the presence of that ground wire is of no consequence.

mike

 

How soon I forget... Last one I dealt with, I think we used a sportster ignition and bypassed the VOES. But yes, it was grounded to the head. The OP did say a 2012 model and reaching that far back in my tiny brain wasn't even considered.

 

Strange to see it on a newer bike. That was the ground for the horn on 2005 (IIRC) and older touring.