I want to add a louder horn to my wife's 2005 civic. I want to leave the existing horn as is and just add a relay to the existing circuit and run directly off of the battery. I don't have a wiring schematic or diagram to show where I can tap into the existing horn wiring? Can anyone help or direct me to a site where I could find a wiring schematic?

Joe

 

I just did this to my wife's 2003 pilot. In 2003 the horns (there are two -a high and low) look like civic horns (the small metal disc). In 2004 they upgraded to the plastic "sea shell" looking horns. I simply replaced the wimpy horn with the beefier one from a 04 pilot.

Couldn't you just replace existing horn with an aftermarket louder one? Is there a reason you want to add a horn instead of just replacing existing? I'll try and find a wiring schematic for you to be able to tap off existing horn relay like your post requests...

 

Thanks for the info Philip. First of all, the horn is located behind the front bumper. Sometimes aftermarket horns draw more current than the factory. I don't want to overload the fuse or wiring. If I can find the wire feeding the factory horn, I will tap into that wire and trigger a relay. Then I will take a heavy gauge wire (14 or 12) from the battery via a fuse and fire the new horn.

Joe

 

 

i just bought one from o'reilly's... better than the stock! but not oem'ish!

 

12ga is overkill. 18ga wire out in the open can handle 10 amps. I doubt your aftermarket horn will pull that much current. Remember to fuse the wire coming from the battery - prior to the relay contact at around 150% of the estimated current draw (NOT to exceed the wires current capacity).

So for example if your new horn draws 5 amps, fuse it at 7.5 amps and 20ga wire will suffice.

Reference material:
(Copper wire in open air for chassis wiring - IE; Not in a conduit)

22ga - 5.0A
20ga - 7.5A
18ga - 10A
16ga - 13A
14ga - 17A
12ga - 23A
10ga - 33A

These numbers are a little conservative so dont worry if you are near the edge.

 

Thanks unevolved and Worldsport, that is just the information I need. This is a great forum. I hope someday to be able to contribute.

Joe