Did the 1953 truck single seashell-style standard-horn use a relay (as used with that same single standard seashell style horn in 1954)?
The 1953 dual seashell horns did use a relay; and, earlier optional/accessory dual horns used a relay.
The Master Parts Catalog is not clear on this.
I can't use the term seashell horn. But I know what you mean. I call the noise making unit the trumpet. Diagrams do not give shape.
Cars used dual horns back to at least 49. They had relays and one terminal trumpets. Cars continued to use dual horns. Hi note/Lo note.
1938 seems to show one two-terminal trumpet, no relay.
1941 Truck diagram shows dual one-terminal trumpets with relay.
1942-1951 Truck diagram shows one two-terminal horn trumpet, no relay.
1952 Truck Wiring Diagram: Not found
1953 and 1954 truck diagram shows one one-terminal horn trumpet with relay.
Do not know about or see any wiring diagrams regarding horn options for trucks.
Engineers decided that it was better not to be "shorting out" an actual circuit at the horn button (big amps)(spark-spark). So using a one terminal trumpet, they grounded it's case thru it's mounting hardware. Let a relay provide power to the trumpet terminal, and just let the horn button energize an electromagnetic coil inside relay at "S" (low amps)(no spark), which closes relay contacts "B" and "H" (big amps). No more buzzing your tooth fillings when you honk.
