2005 Engine compartment 12 volt source

[Bobster1954]

I have a 2005 Thunderbird that I want to add a remote controlled 12 volt auxiliary horn in the engine compartment or behind the grill. I don't want to run a wire all the way from the battery. I am wondering if there is a 12 volt source in the engine compartment that I could use? My idea is to operate the horn with a remote to keep the neighbor cat away!
Thanks to anyone who can help.

 

[biddle]

I use the fuse box tap for my dashcam power.

Example for 12v-

https://amzn.to/3HN8BBr

 

[Bobster1954]

Thanks, What circuit did you use?

 

[jneuenburg]

My idea is to operate the horn with a remote to keep the neighbor cat away!
Thanks to anyone who can help.

You can write down the likely circuits which might be energized with the ignition off, and then confirm if they have power with a multi-tool or test light. Then pick one.