Horn not working

I have run out of ideas. I have a 2003 Pre-Runner 3.4L V6 and my horn is not working. The fuse is good; I'm not sure if I have checked the relay. There is no airbag light on my dashboard, so I don't think it's the clock spring. I checked the voltage with a multimeter and found that when I put the positive on the battery and the negative on the wire, there is 12V going through even when no one is pressing on the horn. I am not sure what to do next. Thanks in advance.

 

Cruise control work?

 

The BCM controls the horn.
And there are no connectors between the horn, steering wheel, or BCM.
No "easy" way to test the circuit other than at the BCM

Or you can test the horn easy enough.
Unplug the horn, (to be safe), Then run a wire from the + terminal of the battery to the terminal on the horn.
There will only be one terminal on the horn. So that makes it easy to test.

The horn is self grounding. It ground through the mounting bolts.

If the horn works when you test it, it is likely the clock spring.

 

Yes, the cruise control works just fine. I will try that in a couple days thanks guys.

 

Initial testing is pretty easy.
Test light from battery Ground to the wire at the horns, have someone press the horn button. If the light lights up you need a horn, if not then plug the horn back in and go to Pin 6 (Green/Red) at the clockspring connector on the steering column. Test light to a known good Ground touch the terminal (you may need to use a needle or other suitable tool to backprobe the terminal), if the horn works then you need a clockspring.

 

Second this... one of my horns had a short and went out. I got a affordable plug and play replacement from Amazon that is working well.

 

Yeah. Easy enough.

What's weird is they chose to use the BCM instead of a relay.
The 2nd Gens have relay.

 

Also, just for OPs learning experience.
When you used your meter and got 12v at the horn.
That was normal.

A common misconception is that a meter tells you the voltage on a given wire.
It does not, it tells you the difference between one lead and the other of the meter.
When you put the red lead on the + terminal, and the black lead on the - terminal.
You had 12v on the battery terminal, and 0v on the horn wire. Remember, the horn is grounded through itself to the body.
The body is grounded by a ground wire to the battery.

So, essentially you did a "battery" check.