Wiring for air horns

[woody44]

I have a pair of air horns, made in Italy, which came with the 67? Elan S3 that I am restoring. The problem is I don?t have a wiring diagram for them. The compressor has two terminals, the relay has 3 terminals identified as follows: ?T? with a red wire. ?B? with a blue wire. ?P? with a red wire.
An additional red wire is wrapped with the other three, but was not connected to anything. The car will have an alternator, and will not have a voltage regulator.



Steve

[twincamman]

I didnt bother ---just hooked up without thr relay ----works good -- -ed

[bcmc33]

The S3 wiring diagram in the workshop manual does not show a relay. Neither does the S4 wiring diagram, but my Sprint does have one as OE.

I would always use a relay with inductive loads ? particularly to protect the aging wiring.
A simple single output relay should have four (4) terminals. You can buy them really cheaply on eBay, and it will be supplied with a wiring diagram.

Regarding the two horn connections ? earth (-) & live (+) are marked.

Brian Clarke
(1972 Sprint)

[types26/36]

Here is a wireing diagram for a typical 4 terminal relay
http://www.ado13.com/techs/relay.htm

[RotoFlexible]

The horn contact and slip ring on the Elan doesn't appear suited to carrying lots of current. As part of my Stage 1 electrical upgrade, I inserted a relay and fuse into the horn circuit, and replaced the feeble get-it-through-inspection horn (which sounded strangled at best) with two-tone "Freeway Blasters" - think Clear Hooters on steroids. Big difference: that little switch now controls a mighty sound.