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Wiring point for anti theft kill switch


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Hi all, when fitting an anti theft kill switch (OFF/ON) would interrupting the circuit for the neutral starter switch still be effective if thieves were to hot wire the ignition coil?

 

Or am I better off grounding the coil wire that goes to the distributor which was plan A.

 

Plan B will be easier to wire but plan A is not difficult.

 

Thanks in advance.

Rodney 😀😀😀😀😀😀😀😀

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Interrupting the circuit for the neutral safety switch would only affect the starter motor circuit. In general, a thief could power up the ignition coil, crank the engine by push starting the car (if it's got a manual transmission or is one of the few automatics that can be push started) and they would be off to the races, so to speak.

 

It all depends upon how much effort a thief would want to expend on stealing the car.  If it's an especially valuable or frequently-stolen car model, you might want to do both Plan A & B.

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The only kill switch that is effective against a simple hot wire to the coil and starter is a switch that grounds the wire from the points. If the negative terminal of the coil is grounded at all times, it's equivalent to points that never open. No hot wire will overcome this, unless the thief takes the time to diagnose the problem. I would only use this with points, however. Such a ground wire might damage an electronic ignition system.

 

The reality is that it is impossible to prevent theft. All you can do is to make it more difficult to steal your car, so a thief moves on to the next one, and yeah, that's like the joke that ends "I don't need to be faster than the bear, I just need to be faster than YOU!" 😉

Edited by joe_padavano (see edit history)
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Not convenient, but when trailering to an event, a high voltage coil wire and a plug wire or two come into the hotel room with me. 
 

From the modern tow vehicle, the fuel injection pump and starter relays may accompany me. 

 

They may get mad and wreck stuff, but odds are, it's still there when you go out in the morning. 

Edited by keithb7 (see edit history)
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4 minutes ago, keithb7 said:

Not convenient, but when trailering to an event, a high voltage coil wire and a plug wire or two come into the hotel room with me.

 

The better solution is to replace the coil wire with a fake one made from vacuum tubing and correct end boots. Now it doesn't even look like anything is wrong.

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Thanks for the replies. Thinking last night that both grounding the coil and interrupting the neutral start circuit is possible using the double pole double throw ON-OFF-ON HD switch that I want to use. 
 

ON Position one RUN CIRCUIT  coil wire open (not grounded).    Neutral Start circuit closed.      Car will start

 

OFF Position two OFF CIRCUIT coil wire open.     Neutral Start circuit open.          Car will not start.

 

ON Position three OFF CIRCUIT coil wire grounded. Neutral Start circuit open.            Car will not start

 

 

This will require a feed from the coil, a ground at the switch and cutting one side of the neutral start wiring. 
 

Many thanks to those that contributed. Am thinking grounding the coil is essential as any hot wire will not work until you remove the ground.

cheers

Rodney 😀😀😀😀😀😀
 

 

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While you can perform both functions with one switch, it puts all your eggs in one basket. Having two switches hidden in two different places provides more security. Frankly, an open in the NSS wire is worthless anyway if the thief applies power directly to the starter solenoid, or just jumps the contacts with a screwdriver. The grounded ignition, however, prevents start even with power applied directly to the coil. If you do decide that you want both functions on one switch, you need a DPDT switch that does NOT have center off.

 

 

Kill switch.png

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Hi Jo,

many thanks for that. Do have a HD switch similar to one shown ( ON/ON ) that would do that. I have decided to take your suggestion and ground the ignition, am a bit reluctant to cut the NSS wires unless I can modify without cutting. (Which I think I can 😀)

 

BTW, it is a convertible so getting in won’t be hard, just want to make it hard to get away.
 

And being in Australia, very few would know how to unlatch the hood, they will be looking for a release cable on the inside. Think this practice must have been inherited from our convict past, most of our cars have inside cable release for the hoods. 😀😀😀😀

 

Thinking your idea has merit in one switch, two positions. Much simpler. 
 

Rodney 😀😀😀😀😀😀😀

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When our number 1 daughterwas ready to fledge to school, found her a nice used toyota and a nice used vw fox. Very comparable and she liked both the same. I decided on the fox as it had a much better horn. Those little Brazillian built jobs, like most VWs of the era, had popout rocker switches on dash for various devices like lamps, hazards, etc. Her shiny preowned job had a blanked space for a switch. Went to pull a part and got one, wired it to kill the ignition power. She would hit the switch on parking and her little fox was never stolen in Austin her entire time there. And never forgot it and ran the battery down cranking it.

 I know… who would!  But it made us feel a little better, and her as well.  

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Studeous, agree! I like those where you can use an existing switch to hide it. Unfortunately this vehicle does not have an unused switch or location that I would install one. My thought was the cigar lighter, but that may be handy for charging a device.
 

So for this one have opted for a hidden switch. After looking at the heavy wiring size of the neutral starter switch, opted to leave that side alone as was not certain if the switch would handle the current without introducing another problem.

 

All mounted and wired up. Many thanks to those who contributed!

Rodney 😀😀😀😀😀😀😀

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