2016 Horn Wiring Harness

[mrlewp87]

I'll provide more details as it becomes necessary. Bottom line; I'd like someone who has a really, REAL in-depth knowledge of the wiring harness that carries the power to the horns. I want to tap into it (after fuse and relay), and have it power a 2nd relay which will then provide power to 2 new horns. A separate, new 12V lead will run to the new relay and provide power to the new horns.
As of now, the Hi-note horn still works. The Lo-note (passenger side) has quit. Not interested in replacing the dead horn, nor in disconnecting the working horn. I'm not about to attempt removing either headlamp assembly again (a nightmare) I'm figuring I may need to remove the splash cover (?) under the engine area.
If I could tap into the bundle of wires easily accessed inside the fuse box, that'd be fine, also. A very good source tells me the horn power is pin #35, but apparently it pertains to a plug beneath the fuse box. That's a bit un-nerving, since I'm pretty sure that requires cutting off all battery power.