<edit>Intend for simple anti theft electronics using fuse box wiring.
better to put switch in cicuit with control signal to relay or 12v output powering device?
extra 12 feet of wire in 12v circuit seems ok but the control driver may not handle more wire length?

K14 Starter solenoid
no relay for fuel pump?

 

Not sure what you're trying to pull power from. You could just install a Soler controller and disable the throttle pedal if you're concerned about theft.

 

Unless he is building an 8 second "Doorslammer" where NHRA requires an external kill switch have no idea what or why he is trying to add one?? Would have been nice to give us a hint!

How can the 1st post in a Thread start with "better to put...??" Better than what??

 

Right. If a relay is used, will it be normally open, or normally closed? That is, must it be energized to close the circuit, or energized to open the circuit? Where does the power to energize the relay come from? A latching relay could also be used - it will remain in either of two states without any power.

Sometimes a kill switch simply shorts to ground to ground out an ignition circuit.

 

Solar controller has an option to disable the throttle pedal.

 

Glad you know or have guessed what the OP wants a kill switch for!
Love guessing games and his has a twist as the #1 post he adds: "it's better than ...." whatever!

Is he trying to beat your <15 milliamp parasitic current draw test result for some silly reason?

I can guess he is not building a C8 Doorslammer or probably does not know what it means! For those that are like the 8 second in the quarter turbocharged C8!

 

And that switch must be in the actual circuit being "killed". No relays there! My questions were actually in the context of "I have no idea what he is asking". My sense was if it was a safety related kill siwtch, and we don't know that, and if a relay is used, then it must be a normally open one, so that loss of power would result in a kill. Since he mentioned 12 extra feet of wire, it sounded like he wanted the switch to be at a remote place, and so if it was an inline switch he would have to run the high current line to the remote location, whereas with relay he could run smaller wires to the relay and put the relay in the existing line. (all my read between the lines without knowing the actual application).

 

Is this kill switch to be used as part of an anti-theft measure?

 

If you just want to have the extra theft protection, the Soler throttle controller is a good way to go since it has a throttle disable feature.

 

I saw this post yesterday and couldn't comment because the purpose of the switch wasn't listed... and still isn't..
IF the car is to used for racing and the kill switch to meet regulations, I believe that it MUST directly isolate the battery.
IF it is for anti-theft.. ??? The alarm system is pretty good already, but using a relay will cut added weight and be much easier to install... smaller holes, smaller wires. smaller switch.

 

This, is definitely the way to go!

 

Reminded of what I did for my 1st new car! It was 1967 and I often parked at the airport. No lock on the engine compartment hood. It was known that crooks when targeting a car would often bring a distributor rotor as a common method for folks parking over night was to "remove" the rotor!

My method was simple. I ran a wire from the hot side of the distributor to a switch in the glove compartment that if flipped would cause a short to ground. Put a low amp fuse in the line. It would crack but no spark. Would take a while to find the issue. However, several times coming home after several days on the late flight was tired and forgot to flip the switch back! BUT carried a metal container of fuses I had to change!

SIDEBAR
On my 1974 Rag Top CJ5 Jeep often parked at the Airport I rigged a simple alarm. It would make noise and perhaps scare a few off. Used a 3 "D" cell flashlight I rigged with a loud alarm, no light. Used a switch I made from a limit switch and held it open with a small aluminum bar that had two thin fishing line cables attached. At the end of each was a clip. I would attach the clip to the rag door metal frame. The passenger side 1st. Then with the door open about 6 inches could attach the other. So if either door were opened more than 6" the aluminum bar would pull away from the limit switch and the alarm under the driver's seat would sound until the "D" Cells would run down!

Recall in Cleveland rather than use the several level parking garage I used offsite parking that was run by gals who had a small van that would take you to the terminal. They were in the booth taking money 24 hours. Told them about the alarm and how to shut if off if ever activated. One day I was the only one in the van and mentioned to the young lady driving that I was concerned leaving it in the multilevel parking garage (which is still there.) She said don't blame you I know some of the folks working there target specific cars to steel. They find a wreck in a junk yard for the ID, steel a similar car and transfer what is needed to get the wreck car registered!

 

Here is why I would add a kill switch, and I have been procrastinating to do so:
1) This car is a drive by wire system. Brake by wire, throttle by wire, no linkages.
2) This car is always connected to a cellular link via onstar and has a cellular modem.
3) The infotainment system is connected to the rest of the car control system, runs android, and has connectivity to other systems via wifi, LTE, carplay, androidauto protocols.
4) The car has a GPS antenna/receiver built in and knows the location and speed of the car
5) The ECM has been cracked, so it is not inconceivable that it could be broken by other groups

It would be terrifying to find yourself in a situation where the throttle was set to 100% and all commands to switch the transmission where ignored, as well as a dead brake pedal.

Does anyone know the particulars of how the throttle body works?
Does it have a spring to return the butterfly to the closed position in the event of power loss?

 

Had to chuckle at your fourth sentence--I had no idea that so many "cooks" stole cars as a side job! Guess not all of them can get well-paying executive jobs in the food preparation industry.

 

Have to watch out for those damn cooks! they have big sharp knives!

Thanks for catching! Cooks have turned Crooks!

 

1 - Corvette is not a top theft target. Kia and Hyundai are. Obscurity and large demand for used parts determine this. Corvette has neither.
2 - Insurance exists.
3 - A thief specializing in Corvette would flatbed it and deal with the spliced circuit in Dubai before resale.
4 - The fact that OP has to ask indicates a skill level that is FAR more likely to introduce a disabling malfunction to the CAN bus, stranding the owner, than successfully thwarting a theft.

TL;DR This isn't 1968, no one is shorting terminals on the ignition switch so they can sell your motor/trans to a Camaro owner and the IRS to a T bucket builder.

 

Unless it's for absolute emergency only, I would not install one of those on a late-model street vehicle. All my race cars had them, but the installed electronics were designed to accommodate being shut down in this manner in conjunction with the ignition switch.

 

Ah yes! Never stole a car BUT my friends and my 1st drive was made that way! A number of times before we were old enough to get out driver's license!. My friends dad had a standard shift two door '50 Olds. He would fall asleep on his favorite chair after dinner. My friend would be sure he was sleeping and with aluminum foil would go behind the ignition switch and short the terminals putting power to the distributor. He lived on a hill so he would release the emergency brake and let it roll. When going fast enough would have it in 1st gear clutch depressed. Pop the clutch and it would start. It stopped a few times on a flat surface. Had to crimp the aluminum foil better on two of the ignition switch terminals and my job was to use a length of wire and get the starter motor to crank! Recall there were sparks!

The key was to get back before his dad woke-up!

 

Right. And in those cases its not meant to be a hidden switch to prevent theft, but something that can be easily found in emergency.

 

And some crooks have rehabilitated themselves during prison and when they're released, they become cooks!