Kill Switch - once again

[Jgonick]

I'm about to put a kill switch on the starter wire (PPL-6) under the dash. I was trying to figure out if there was a way to hook it to the horn so if someone tried to start the car the horn would honk. The problem I run into of course is the horn is activated by closing the ground (BLK-28). Any ideas? In the past I thought I read a post about this, but I couldn't find it.


85 K10

 

[Hunter79764]

Someone with more experience could jump in, but I'd think if you have a Single Pole Double Throw (SPDT) switch, have your incoming ignition wire feed the "Battery" terminal, position 1 gets the other side of the ignition circuit, and position 2 goes to the hot trigger of a relay. Then have chassis ground on relay leg 30 and the horn wire on leg 87.

 

[Jgonick]

I believe you are correct. I started thinking about adding a relay right after I posted.

Thanks

 

[Elliot W]

You could always add a second horn in the engine bay dedicated to the switch.

 

[Bextreme04]

The physical horn button actuates the ground side of the solenoid for your horn relay. Power is always applied to that circuit, so you would likely need to have a circuit that provided a switched and fused power to the horn itself only when the starter was attempted to be engaged with the kill switch active. This would likely require two separate relays. I would think maybe a single SPDT bosch relay with pin 30 coming from the starter signal feed. You could then split the feed from 87 and 87a to the starter and a second bosch relay for "alarm" function. Actuate between starting the engine and triggering the horn with a switch to actuate the first relay. I would suggest that vehicle start requires the relay to be actuated. Default setting(relay not actuated) would trigger the horn when you try to start

 

[Ricko1966]

Or just wire 2 Bosch relays to go into feedback loop when provided a ground. Triggered from the dome light switch and activating a horn,open the door the horn honks,BEFORE they've smashed your column and are trying to start the truck.

 

[prestonwood9]

I literally just installed this in my truck. Does exactly what you want. I used 2 relays but after I got it all setup realized I could have just done it much simpler with a single relay. If you still are looking for ideas feel free to send me a direct message. It can actually be super simple. I even think I found a pretty sweet mounting/hidden spot for the switch itself. I can show you the exact parts I ordered from Amazon.

 

[Hunter79764]

Just another idea, semi on topic. On a different forum, there was a car with a floor dimmer switch set up as an ignition passthrough (or other kill switch setup). Actual dimmer function was in the column, but trucks of our vintage could easily have the floor switch, and the majority of the general population doesn't have a clue that it might even be there.
Another topic was to have the kill switch operate the fuel pump, not the starter/ignition. When there's a no-crank situation, they are going to start digging to find the reason why. When an old truck cranks but doesn't start or dies after a short while, they will come closer to cranking and cranking until the battery is dead and you will find the truck a short distance away, albeit with a busted window and trashed steering column...

 

[prestonwood9]

So I just bought a basic Bosch style 5 pin relay off Amazon. Cut the starter wire under the steering column. Ran the wire coming from the ignition into the 30 pin. The 87a goes to the horn. Instead of working up an additional relay to make it a ground connection I just ran the wire through the firewall and down the left front panel and connected it to the horn on the drivers side. There is an existing wire bundle on my 80 that goes down this side already. The 86 pin has to be hooked up to a constant 12v power source. I used the small momentary switch for the 85 pin. I mounted it on the left side of the dash in the corner. I actually have two installed as I was going to use one for something else. I feel like the button is very difficult to see if you didn’t know it was there. I actually installed my relay in a box behind the seat next to an amp but everything could fit easily under the dash if you wanted to hide it all. The 87 pin has to be connected back to the other side of the ignition wire you cut so it can connect the circuit to activate the starter. Lastly, under my steering column there is a red wire from the key, it then runs to a device that ensures the vehicle is not in gear before activating the starter, then a purple wire (I believe) runs to the starter. I actually cut the purple wire and used it to send to/from the relay. Hope that makes sense, let me know if you have any questions.

 

[Grit dog]

Or just wire 2 Bosch relays to go into feedback loop when provided a ground. Triggered from the dome light switch and activating a horn,open the door the horn honks,BEFORE they've smashed your column and are trying to start the truck.

How do you shut it off when YOU open the door then?

 

[Ricko1966]

How do you shut it off when YOU open the door then?

You break the power lead, hidden toggle,reed switch, you wouldn't want to switch it off the door lock because if someone unlocked the door it would be disarmed. I did this 25 years ago,it was my instant on alarm we talked about on a different post I just had a hidden toggle.

 

[Johnny Atomic]

You could always add a second horn in the engine bay dedicated to the switch.

and put the second horn in the cab with the theif. Make that sorry ass human being lose their hearing.

 

[Elliot W]

and put the second horn in the cab with the theif. Make that sorry ass human being lose their hearing.

Lol not a bad idea.

 

[ReefkoiC10]

You could always add a second horn in the engine bay dedicated to the switch.

Or even better have the horn replaced with a .45 mounted on the dash

 

[Doppleganger]

and put the second horn in the cab with the theif. Make that sorry ass human being lose their hearing.

They'd lose more than that. Keep a waterproof cover on the seat.