RE: horn relay problem, 5 prong to 3 prong?

["Brian Shorey" <bshorey@domain.elided>]

> Argh....The horn is gone. I suspect it is the relay (I hear clicking
> from it when I press the horn, and the fuses are OK). It went out when
> I tried to make this woman in an Exploder realize that she was merging
> into me on the San Mateo bridge.
> This is in a 74 Spider. The horn relay is on the driver side of the
> firewall, and it has 3 terminals. When I called my kind suppliers at
> Alfa Parts in Berkeley (recommended, albeit the city council of theirs
> bothers me) and ordered the relay, they said that Alfa now specifies a
> Bosch replacement (the FAMM is NLA).
> This Bosh relay has 5 terminals. I tired matching the little numbers on
> the diagrams when hooking things up (36 to 36, 85 to 85), but no luck.

Go out and buy any generic 3 prong horn relay.  It's just a relay..

Test what you have first.  Apply voltage to the horn side of the relay and
see if the horns work.  I've never seen a horn relay fail.  I have seen horn
failures when the ground on the horn gets grungy, or when the switch (horn
button) has problems, but never the relay itself.

So, bypass the relay and apply voltage directly to the horn and see if they
work.  If they work, then yes, you probably need to replace the relay.  If
they don't work, then the relay is probably fine and your problem is further
down stream.

The Alfa horns are grounded through the mounting bolts.  Common failure
point..

HTH,

bs

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