If carbon builds up on those contacts, it can add resistance which can alter the pitch and/or volume of the horn. On a dual horn system (the harmonic horn tone many cars have) a loose connector/wire near one of the horns could make one work intermittently. A relay seems like the more likely issue, and really easy to test if there is an identical relay that can be swapped out that isn't vital to the car/safety while testing.
Hi. Thanks for the clear information. I did subscribe. Before I watched your video I watched one where the guy slopped the dielectric grease all over the metal contacts on a trailer connection he was installing; both the male and female sides. Is he just totally misinformed?
