I have a NO Horn issue here I could use some help with on my 2005 sc430.
I checked the fuse in the fuse box under the hood on the passenger side and the 10 amp fuse appears good.
I check the horn connectors and they appear firmly connected. I didn't see any fuses associated with the horn on the drivers internal fuse box on the kickpanel.
I'm not sure where the horns are grounded to, maybe someone can let me know where?
Is the replay in the same box as the fuse for it's not clearly identified. Another areas I should check?
Any help would be greatly appreciated.

 

First things first, get the multimeter out. Hook it up to the leads at the horn. Have someone push the horn , and see if you are getting power to the horn. Then you narrow down from there.

 

I agree with Coleroad that testing to see if you have power at the actual horn is the first place to start.

Are you having any other problems? Do your steering wheel radio controls work?

Do you know when the problem started, or did you just go to use your horn and it didn't work?

 

Please see this thread:
https://www.clublexus.com/forums/sc4...o-and-nav.html
pay close attention to comment #6 and #12