Twilight Zone horn works no fuse or relay

You're right, there is no dedicated Horn relay or fuse. What you originally circled was "S-Horn", which is unused in US market. Possibly security horn in other markets.
The horn is operated by the Integration Relay, which as it's name suggests, integrates several functions into one unit. The Integration Relay is also known as "Unit E" which resides in the Engine Room Fuse/Relay Block.
Once you disassemble the Engine Room Fuse/Relay Block, you can access the connectors for Unit E, and diagnose the circuit from there.
By the way, it would be a good idea to disconnect the 12v aux battery and take the usual precautions while working on the electrical system.

 

Just Curious, Mine is doing the same thing from a front end collision. Did you ever get this repaired? If so How?

 

Hello everyone. I have a Toyota Prius 2009, T3, probably a Gen2 model. I have all yellow lights on, abs/ related to the front wheel speed. Bank 2 Lambda Sensor—issues and three lights related to that.

Before that, there was some issue with the car as it was used to beep horn all times. And finally, HORN went dead too.

What could it be? Is there anyone who could please guide me?

 

You should create a new thread in the Gen 2 forum. Include a lot of information about your problem and the history of the car. Then you may get some help.