horn honk relay

I want to hhok a kill switch with a relay so that when active it will honk horn and not start. The diagram i found has it wired to the + side of horn. Mine is negative coming out of column. Is there a way to invert that or what. Thanks Michael

That's normal 3-terminal horn relay wiring; 85 to grounded horn button; 87 to horn +12V; 30 & 86 to fused (and usually switched) +12V. But IMO you'd be better of with a mere grounded switch in parallel with the existing button - ie, to the existing relay's "S" aka 85... Maybe a dual terminal switch else isolation diodes depending what you mean by "not start" - ie, also ground the output of you open-collector ignition sensor. To "not crank" is a different issue...

Wanting to add a kill switch to a 2011 gmc sierra. just thought it would be a added bonus if they did break the ignition and try to crank it, the horn would honk. Any help with a diagram would be much appreciated. Thanks

That's different to what you originally asked. It sounds like you already have a diagram. My description should be enough info, but if it isn't someone else will have to help you - IMO this involves legal issues and too high a chance that you will damage something.   Good luck.

hornnumb2 wrote: I want to hhok a kill switch with a relay so that when active it will honk horn and not start.

What you're proposing is a basic "Ghost Switch" starter interrupt. No problem, installers do these many different ways, all the time. However, you want to "honk the horn" when the ghost switch is active, ie, has not first been disarmed. There are two issues with this strategy: A: The horn will sound every time the operator forgets to first deactivate the ghost switch. This will drive him AND his neighbors crazy. B: The horn-honk, then-it-cranks, will give away the presences of "a device" to observant people. I have ghost switches on several of my vehicles, but not all of them, and the fact that it doesn't crank is my cue to deactivate the system in whatever car I happen to be in that has a deterrent installed. I forget frequently enough, that if I had included a horn-honk when active, it wouldn't have lasted long before I would have removed it. My neighbors would be yelling at me.

Noting too that starter interrupts are easy to overcome. (Hence why at least disabling ignition or other critical sensors is important.)

oldspark wrote: (Hence why at least disabling ignition or other critical sensors is important.)

I said "that it won't crank is my cue to disable the system..." I didn't say what all is protected by the device other than the starter. One of my recent posts was regarding driving two relay coils with a 200ma DEI trigger. This is my F250 Diesel with remote start. I based my passive ghost switch on the 'honk the horn to bypass' diagram in the Relay Schematics section. I enhanced that device to also interrupt PCM power, remain activated by the factory DAP, (so I can shut off the engine, but restart it if I haven't opened a door) the factory horn has to sound with the alarm (I don't like sirens, I use factory horns), the ground-when-armed output prevents disarming the ghost switch, and of course the remote start has to deactivate the ghost switch as well. I ended up with 10 relays in my device. I just completed a 3,500 mile, 11 day trip since the install. It functioned flawlessly, exactly as intended, and gave me the peace of mind that my truck was going to be where I left it the night before when I came out of my motel room the next morning, which was my primary objective. Peace of mind. Like any security device install. It may not be perfect, or unfalable, but it would take a LOT of time to figure out what I've done, and defeat it. It took over 30 hours to install it. I doubt a thief would take the time to figure it out. He may do a lot of damage before he gives up, but it would still be there in the morning. Along with the trailer and the car inside the trailer. Regards

And I provided a mere comment that was not directed at you or your specific reminder or system. It's a simple statement that starter interrupts are very easy to defeat. I hoped it would be useful info for those that think "preventing" cranking is a major security feature (ie, older vehicles merely need one jumper wire with an optional second else a piece of metal to crank and run an engine).