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2010 XT Limited 4EAT
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Discussion Starter · #1 · (Edited)
Hey everyone, was hoping I could get some input from people with better electrical skills than me. I am going to install the TM80 magnums (twin) horns into my foz and have read many places about needing thicker gauge wire as well as a relay.

The wire gauge I'm not too worried about because I can just match the wire gauge to the amount of current they will draw, but more of my confusion is towards what size/type of relay I need as well as how exactly to wire it. I don't plan on keeping the stock horns, but I know I obviously need to tap into somewhere in order for them to power when I hit the horn.

The specs of the horns are below, again I have the dual tone so any insight would be helpful. Thanks a lot.

EDIT: After a little more research, it looks like a 30A relay is close to as low as they go and I will probably use 14 gauge wire to be safe for the current draw. If this sounds correct, how exactly would I wire them to work correctly? I assume I will have to draw power from the battery (which I can do with a single wire), to the relay, then to the horns with both of them being grounded. Would I run the stock horn wire to the relay as well for the signal? Does this sound right?

 

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2009 2.5xt 6 Speed Swap version 8 6 speed sti trans with r180
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4,150 Posts
Sounds about right.

Usually the horn ground is the chassis of the horn itself touching the chassis of the car. If for some reason you ended up mounting them in an insulated fashion you can run a ground wire From some part of the chassis to them.

If the total of the two horns amp draw isn't over 30 amps, the 1 30 amp relay will be good.

A relay has typically 4 posts, one of which is usually sideways compared to the others. The sideways one and the one directly across are usually the high amp ones going from your battery or fuse panel into the sideways post and then out to your horn + terminal on the horn.

The other two are a low amp 12 volt supply. So one needs to be grounded ground, and the other needs the + signal either from a new switch or from your original horn wiring they will give 12v +.

In some cases when you push the horn is actually completing the ground and not the 12v part. In that case you'd have a permanent 12v+ hooked on the relay and connect the ground to the original horn switch wiring.


A relays purpose is to keep you from having high amperage which creates heat and fire dangers in the cab. This way you have low power switches and thin wiring on the inside. They tell a switch (relay) on the outside to do the heavy work away from you.


Sent from AutoGuide.com Free App
 

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Registered
2010 XT Limited 4EAT
Joined
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1,447 Posts
Discussion Starter · #3 ·
Sounds about right.

Usually the horn ground is the chassis of the horn itself touching the chassis of the car. If for some reason you ended up mounting them in an insulated fashion you can run a ground wire From some part of the chassis to them.

If the total of the two horns amp draw isn't over 30 amps, the 1 30 amp relay will be good.

A relay has typically 4 posts, one of which is usually sideways compared to the others. The sideways one and the one directly across are usually the high amp ones going from your battery or fuse panel into the sideways post and then out to your horn + terminal on the horn.

The other two are a low amp 12 volt supply. So one needs to be grounded ground, and the other needs the + signal either from a new switch or from your original horn wiring they will give 12v +.

In some cases when you push the horn is actually completing the ground and not the 12v part. In that case you'd have a permanent 12v+ hooked on the relay and connect the ground to the original horn switch wiring.


A relays purpose is to keep you from having high amperage which creates heat and fire dangers in the cab. This way you have low power switches and thin wiring on the inside. They tell a switch (relay) on the outside to do the heavy work away from you.


Sent from AutoGuide.com Free App
Awesome, thanks - appreciate the help (again) :)
 
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