Air Horn problem, different tones

[Lexlee]

The air horn I have fitted sounds great when wires are put across a 12v battery, since it has been fitted to the vehicle it sounds high pitched compared to the deep tone it should have. The deep tone can be obtained (but not always) if I flas the head lights at the same time a operating the horn.
Any help greatly appreciated.

 

[Devonchris]

It needs 12v supply via a fuse from the battery to a relay and the existing horn circuit as the trigger. Is this how its been fitted?

 

[telectrix]

volt drop???

 

[Lexlee]

Hi ,
Thank you for the reply,, I used the 12+ Wire for the factory fitted horn to power the air horn. The earth is to the bulkhead where there are other earth wires fitted.

 

[Lexlee]

Sorry havn't checked for a volt drop, take it I can put the tester on the connection at the horn and see what voltage I get when horn operated with and without head flash.

 

[telectrix]

you need to use the existing horn feed to energise a relay. this relay being supplied from the battery via a suitable fuse, then to the air horns.

 

[Lexlee]

Oh ok , think I misunderstood first reply, so if I have this right,
1. Original pos for vehicle horn to a relay
2. Power from battery to (30) on relay then (87) to horn.

There is an extra fuse box on the bulkhead as it's an ex ultilities ( water board or electricty board Defender) so will use supply from there as cable to it is fairly substantial.

 

[static zap]

Defender .... earthing issue ? (everywhere!)

 

[davesparks]

If it's a landrover then it's probably something to do with the magic smoke having leaked out, get a fresh borrow of Lucas magic smoke and top it up!

 

[dmxtothemax]

Those types of horns require LARGE currents,
you will need substancial wire
And a stiff supply
Cables and connectors should be at least 30A rating.
Try it and see !
I had the same problem.