When I bought my 1972 250C last week, the horns didn't work. The
previous owner had replaced the stock horns with a set of Hella units,
and he said that they had worked after he installed them. When I took
the horns off and jumpered them directly to the battery, neither one
I replaced the Hellas with a pair of Fiamm horns, and they worked for
about a day. Today, I honked the horns and they both cut out. Same
problem as the others - I disconnected the horns and wired them
directly to the battery to test them, and neither one worked.
The horn circuit is relatively simple. +12V from the hot side of the
horn fuse is applied to terminal "A" of each horn, and terminal "B" of
each horn is connected to a wire that is grounded through the steering
wheel horn switch. The car, as well as all four horns it's killed,
are twelve-volt, so it's not like I accidentally put in 6-volt horns
or anything like that.
I'm thinking that the Fiamm and Hella horns may be drawing more
current than the stock horns, and that they should have been wired
with a relay connected directly to the battery, so that the stock horn
wiring only has to activate the relay, and then the relay would
provide power to the horns directly from the battery.
The only thing that puzzles me is that if the new horns are drawing
too much current, I would have expected the horn fuse to blow, rather
than the horns themselves dying.
Has anyone ever had a similar experience with aftermarket horns?
"After things go from bad to worse, the cycle will repeat itself."
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