Have searched thorugh the archives & didn't find my question addressed...

I need to replace the lower of the two horns on my '94 E320 Cabriolet as it just makes a "tup" sound when I try it--the upper horn is fine. Which frequency is the [physically] lower horn?

Established that the problem is the horn and not wiring. I reversed the two leads from the working [upper] horn down to the lower horn & the lower still didn't work. Also verified the wiring by testing the lower 2 leads on the upper horn & it still worked fine.

I've seen units for sale listing the 500Hz 433Hz combos & also a 433Hz 300Hz combos. But if I only buy one horn, which should I buy?