Batboard

I'm looking for some help with a little project I am thinking about. I have a 2013 Tahoe, the siren I currently have installed is a Four-Function
Undercover Siren Model 30.2104 http://www.able2products.com/pdfs/30_21 ... ctions.pdf

What I am hoping to do it add a DPST on/on switch off of the horn wire to the white wire coming from the factory horn so that in position 1 the factory horn sounds and position 2 the air horn on the siren sounds. My only hang up is where is the best place to put in the cut out switch. Is there a 12v+ signal the comes out of the switch on the steering wheel?

Any help would be greatly appriciated

No the signal is ground side. You would have to have a relay to switch to ground trigger to 12v to use the siren..

Would it be easier to take the run the switch above from the 12+ horn in the engine compartment? I've done a lot of installs but never had to do a ground trigger relay

also if I do a relay switch to ground trigger what wire would I tap from the horn ring?

Thanks

Horn Trigger tan - horn switch or BCM left of steerng column, brown plug, pin 18