My car came with an aftermarket steering wheel and no horn, which I need to pass inspection. It also conveniently has an aux switch for fog lights that dont work. I am trying to wire the horn up to the switch but either way I try it it isnt working.

Battery -> Horn Positive with Horn Negative -> Switch -> Ground results in the horn making a weak noise of it grounding out less "HONK" more "tink.." and that is all it gets. If i play with the ground and move it around and let it spark it just does the same thing, a faint "tink" with every spark.

Power Source -> Switch -> Horn Positive with Horn negative grounded does the same thing.

I was hoping to go for inspection this saturday, any input greatly appreciated!
2 powers? 2 grounds? I was told an airhorn in the glovebox wont suffice..

 

Sounds like you have a dead horn. I would hook it up through a relay, myself.

First, ground the horn.

Next, run a wire from pos of horn to switched side of a relay.

Then run 2 power wires to the relay (or 1 wire can be split into 2 at the relay.) You need 1 for the switched side to send power to horn and 1 to power the relay. (control side)

Last, run a ground wire from the relay to your switch, and ground the other side of the switch.

Grounding in this way keeps the power off the switch and sends it remotely to the horn. This is the same set up as the "light relays" that everyone is doing. Also, I would use a push button "spring" switch instead of a "toggle".

 

Find out if the horn itself is working first. I find test wires work great for this type of thing. clip to wires directly to the - & + horn contacts. Hold the - wire to the - battery post and then hold the + to the + battery post. Only need to hold it there for a second or 2 as the horn should either work or not. No need to 'play' with the wires or let them spark.

Using an actual switch to test isn't always a good idea, like in this situation. It could be a bad switch, wiring connections would be bad, wires crossed while in a rush for that quick test, etc, etc. Test the horn or whatever first then add a switch, relay, etc. Start with the basics and then add to it.

 

Have you tried the horn with the engine running? The battery is 12V, while the car runs on 14V. I have seen this make a weak horn work properly.

 

the horn was bolted to the car and grounded and when i first put power to it before adding the switch it would work properly. but then we couldnt replicate that later on as it would just spark again

we also ran out and grabbed a push button for the horn to see if it was the switch and the same thing happened, when i pushed the button it just made the faint tink noise.