Originally Posted by ArthurKotb

The entire metal body of your car is negative/ground. There is a wire that comes from the relay to the horn. It should be near the horn. (see photo) That wire is positive. You didn't have to remove the horn to test it, but it appears to me that your video shows it hooked up backwards; positive to the horn body and negative to the input voltage. I'm not sure that it makes a difference. The sound coming out was not normal. It should have been quite loud. Positive wire from the battery connects to the input tab on the horn (not the body). Hold the negative wire firmly to the metal part of the horn, but don't touch the positive and negative together; lots of sparks. You probably didn't make a good connection.



When you press the horn button you are closing contacts in the steering column that engage a relay. When the relay engages it closes a circuit that provides power to the horns. The relay could still click and have bad contacts, preventing power from going to the horns (but not likely). If you are measuring 12 volts at the wire that connects to the horn, when someone presses the horn button, then the relay is good and the horn is getting power. Some cars have a jumper wire from one horn to the other. Some have 2 separate wires. (The reason for the relay is because of wire thickness. The wire from the contact in the steering column is small, because all it has to do is close a circuit to the relay. The relay engages and closes the circuit on much thicker wires because the horns draw more amperage.)

If you have done the test on both horns and one doesn't work and the other one just makes that funny noise in your video, then I would say the horns are bad. You won't get shocked, you're working with only 12 volts DC, much too low to shock you. Get a good solid connection to the horn's body (negative) and the input contact (positive). The horn should be really loud if you have a good contact.

In my attached image you see the 2 horns on my 04 T4R. You can see the wire on the right one. The wire for the left horn is hidden by the horn. Something I've not noticed before is a set of wires on the left going to a small holder. This is probably a fuse to protect the wires from overloading. I'm not sure because I've not seen this on other cars.

You don't need to remove the horns to test them but it's looking like they're both bad. There is one more test you could do if so inclined and if you have a multimeter. Plug the wire to the horn to the red/positive lead of the multimeter. Clip the negative lead to the body or negative post on the battery. Set the multimeter to DC volts in the 20 volt range. Blow the horn. Meter should show 12 volts DC.

If you are satisfied with your tests, buy 2 new replacements; hi and low. (I'm a pack rat and I would keep the old horn that still works. Something to test with or give to someone else.)