Pretty sure I did a post on this maybe a year ago but I couldn't find it.

04 Sport horns have stopped working. They were working fine and one day I decided to see if they would work on my rav4. I took them off swapped and they didn't work so put them back on the 4runner. Since then they stopped working.

This was probably over a year ago and it was off the road but now back on so I wanna fix the issue. Checked fuses and they are fine, Swapped the relay behind the dash with the one next to it and didn't work. Can hear a clicking when pushing on the steering wheel.

Any other suggestions? Thanks

all you did was unplug them and transfer to another vehicle then move them back?

Have you checked the grounds? Use a multimeter to verify continuity from this part of the horn to the frame

Also make sure pins in the connectors arent bent or wires havent come loose. Its a fairly dumbproof system but ive seen where the horn was tied to the radio and some other components so make sure youre fuses are good. Sometimes replace the fuse regardless if it "appears ok"

YES. I had a no horn work problem on my Matrix, pulled the ground fastener and it was corroded, but looked ok, replaced it with a fresh fastener and bingo, horn worked.

If you hear a clicking under the hood when you press the horn button on the steering wheel then the relay should be working. Check the voltage at the horn connection when the horn button is pressed. To check the horn, run a jumper wire from the positive post to the horn's connector. (You can also remove the horn from the car and put the connector tab on the negative post and the jumper wire on the positive.)

The relay could be working but still not providing voltage to the horns. It could have a burned connector inside. If you have voltage at the horn connector then the horn is bad.

On an old '91 Camry I had both horns quit at the same time. Sounds strange but they did. I replaced the relay and nothing. I checked voltage at the horn and it was 12.7 vdc. I bought new horns, problem solved.

horn fuse and go from there, check the wires going to the horn for power like other suggested.