horn works only on one side

without knowing that steering wheel, I would assume that both horn buttons use the same relay. I would think that they tie in together before the relay, look into that.

I cleaned the contacts and the horn worked fine on both buttons on the steering wheel. That was a year ago. Today, the horn stopped working again. I get an audible click in the engine compartment near the firewall whenever I press the horn button but no horn sounds. Do I need a new relay? If so where is it located. Or should I try something else first?

run a wire from the battery to the horn.does it sound?

Yes. It sounded when I ran a wire from the positive battery terminal to the horn.

So now I removed the horn relay switch and there is no click when I push the horn button. Before I spend $50 for an exact GM replacement I would like to test this old one to verify that it is indeed defective. I have a multimeter. What steps do I follow to test it. I should note that this GM relay is called a "littlefuse" horn relay. Also I have photo image of my relay.

Problem solved. All I had to do was remove some tarnish on the 45-year-old horn relay terminals. Works fine now.

good troubleshooting gl,