Technical '57 Corvette horns

Hoping for some input on how they were wired, or how they get the signal to honk?
I'm helping a friend who bought a '57 Corvette earlier this year, and there were no horns. He got a pair of new replacement horns and before installing them I looked behind the grille and located what is likely the feed wires, one at each side of the grille. But I put a test light on them and as soon as I connected the test light to the wire it lit up, and I hear the horn relay pull in.
I assumed the wiring to the horns wouldn't have power constantly, but this does. Seems maybe either I'm wrong about how it's wired, or maybe there's an issue in the horn button that's keeping power to the horn constantly?
Anyone who can maybe give some guidance as to how the system works, or whether it's constant hot, or ???

 

Look for the wire from the steering column that connects the horn relay contact, in the upper bearing, to the horn relay.

The wiring is pretty simple, the horn relay gets power all the time, and it gets ground when you push the horn button. When that happens, it sends that power up to the horns. On a corvette, make sure the horn ground wires are in place...look at the assembly manual for all the details. If he doesn't have the assembly manual, he needs one. Really.

The relay could be wired wrong.

 

oh...there is a pdf of the 57 AIM on the internet, search for

1957AIMwebOCR.pdf

but it might be hiding well.

 

Relay maybe wired incorrectly or stuck closed

 

Thanks!!
The relay appears to have unmolested wiring that's original, so maybe the horn button is somehow making all the time. When I used my test light on it I found the left and center terminals both were hot, and nothing on the right terminal. I expected to only see power on the one terminal, so guessing maybe the horn button, or column wiring is shorted?
When I put my test light on the two wires out at the horns I hear the relay making noise with the test light load on it. Going to look into the steering wheel and see if I can find a reason the horn wires are constantly hot.
Any idea if the horn button just pries off the wheel, or how it's attached?

 

pushes in and turn if I remember right.

 

pulls straight out. Other brands of cars have to twist first, but not Chevys.

 

Thanks. I'll disconnect the battery and try removing the cap.