Air horn wiring question

[A930Rocket]

*** This isn’t my truck or horn, but a question asked on the F150 forum.***

Does the wiring look right on this diagram for the application?

It seems like the red and black wires are mixed up, connecting to the battery. The horn button completes the circuit on the negative side. What does the red wire from the horn to the battery do?

How would you wire this?






I’m thinking it needs to be wired like this, but I’m no EE.

[javadog]

Usually black is used for ground and red for positive 12V but they decided (and wired their product) differently.

[RANDY P]

A fuse, and it looks like the compressor would run with key off.

I would not try that with a compressor unless you want a dead battery. Try a relay on the +12 tied to a key switch cutting off battery while off. If the system isn't leaking the horn should still work with key off, for awhile.

[A930Rocket]

A relay on switched power to the positive side is a good idea.

Is picture 1 or picture 2 the better way to wire it?

[javadog]

I always put the fuses close to the positive battery terminal. Like right at the terminal.

And, I generally use red wire on the positive side, black on the negative.

[911 Rod]

I had this problem years ago and couldn't figure out why the horn stayed on. I believe the first diagram is correct.

[Zeke]

It will work either way, electrical current don't care. But a fuse on the negative wire leaves the circuit hot to seek any form of short (ground) until something burns up. I vote #2.

[A930Rocket]

Here’s what I’m thinking now. This will add a fuse of both positive wires and a switched relay, so the compressor doesn’t run all the time.

[911 Rod]

Is this a train horn?
They are nasty!

[Zeke]

^^^ Could be, huh?

[Scott Douglas]

The friend I partnered with in the Plymouth Trouble Shooting contest had a set of chimes off a diesel locomotive in his Scout.

[RANDY P]

Picture #2. Conventional and someone isn't gonna mistake it for a hot lead.

[A930Rocket]

Not my truck. Not my horns.

I just thought it was an interesting question how to wire it.