I want to change the horn on my 2009 H3, Does anyone know if there is a horn relay in the factory wiring or do I have to add one.

 

https://schwarttzy.com/h3-hummer/

Near the bottom of the page you'll find a wealth of info in the form of pdf files. Wiring schematics are there, and although there isn't one specifically for an '09, I can't imagine the horn wiring changed between those years. Someone could correct me if I'm wrong, but it's a good starting point.

 

Thanks for your response. the bottom of what page? I've tried various searches but to no avail. My question was simple, Is there a relay in the factory horn circuit or not. Does anyone know the answer?

 

I think his answer was simple: Look at the wiring diagram and find out. On the page he pointed you to, search for "pdf" or "wiring".
Why do you assume that someone would necessarily know and not have to look at the wiring diagram themselves?

 

YES, I CAN SEE IT, JUST OPEN YOUR EYES AND LOOK HERE:

 

Change the horn already, one green wire from a relay in the box. Same on all late model GM vehicles.