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Discussion Starter #1
After another display of motorist idiocracy, i have decided to upgrade the horn on my 147 to the same Twin tone "safety" horn that was on my 145.

I now have the kit but i need to wire it in. Basically i need to wire the horn switch into the supplied relay and then wire the compressor and a dedicated, fused 12v supply to the other part of the relay. All very straught foreward.

Where can i connect the new relay to the existing horn button? I will not wire cables into the steering wheel for obvious reasons. My thoughts are to remove the existing Relay out and run cables from there but i do not know where the horn relay is (the handbook says nothing).

Can someone help? where is the horn relay?

Cheers in advance.
 

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Why not wire the relay to the output wire at the horn on the original loom? Is it switched negative or positive on the car?
 

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Discussion Starter #4
Why not wire the relay to the output wire at the horn on the original loom? Is it switched negative or positive on the car?
Don't know much about electronics, surely sending 12v's to the "switch" of the relay is not a good thing?

my solution i believe is the best course of action, i just need to know where the origional Horn relay is.
 

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It sounds to me that you could do more damage that way.

A horn either has a switched positive or negative feed.

If it is positive, the the horn earth return is through the chassis.

If it has an ignition switched negative, then the return is a positive supply and is only live when the ignition is on.

There is no need to go messing about with the relay or wiring. At least with my suggestion, the horn will either work or not, and there is no danger of blowing fuses.

It also means no auxilliary wiring from the cabin has to be passed into the engine bay.;) Far neater solution. Hope that is of some help.
 

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Discussion Starter #6
Why not wire the relay to the output wire at the horn on the original loom? Is it switched negative or positive on the car?
It sounds to me that you could do more damage that way.

A horn either has a switched positive or negative feed.

If it is positive, the the horn earth return is through the chassis.

If it has an ignition switched negative, then the return is a positive supply and is only live when the ignition is on.

There is no need to go messing about with the relay or wiring. At least with my suggestion, the horn will either work or not, and there is no danger of blowing fuses.

It also means no auxilliary wiring from the cabin has to be passed into the engine bay.;) Far neater solution. Hope that is of some help.
Not 100% sure i am following you. Do you mean, remove the wiring from the origional horn and wire that into the supplied relay?

Still confused, what is stopping me from just unplugging the wires going to the existing horn and plugging them straight into the compressor?
 

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I fitted an air horn to my 156 years ago.
Because the original horn also used a 20A fuse (which is what the airhorn also needed), I didn't bother with a new relay and just wired the compressor straight to the original horn connections.
 

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Discussion Starter #8
I fitted an air horn to my 156 years ago.
Because the original horn also used a 20A fuse (which is what the airhorn also needed), I didn't bother with a new relay and just wired the compressor straight to the original horn connections.
Woohoo, that is exactly the answer i was looking for!

Cheers,
A.
 
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