The Ultimate Kill Switch ?

[Mach1 Driver 584]

On Page 1 of the PDFs below, it shows three methods to disable the ignition. Page 2 shows three ways to disable the fuel, and page three shows how to use a magnet and reed switch to turn those systems off. The advantage of a magnetic reed switch is that it can be hidden behind any plastic part and no one will know where it is or how to turn it off. With a normal kill switch you run the risk that the thief will find the switch. This won't outsmart a determined thief, particularly one with a tow truck, but it will stop most.

These are the magnets on my key chain. These little guys are very strong for their size and are normally used as jewelry clasps. They come in pairs with a small through hole down the axis and a larger hole that goes partway down on the other end. I used 30 lb mono-filament, tied a knot and pulled it into the oversize hole. Pull on the loop and you can separate and hold one of the magnets. If you don’t want to hang the magnets off your key chain you could just let the magnet grab on to a chunk of steel somewhere in the car and it won’t go anywhere. I prefer to remove the magnet from the vehicle.

The reed switch sits to the right of the magnets. It is small but the electrical specs are more than adequate for the job.

This is a demonstration of how well the magnet and reed switch work. Here we have an easily removable piece of plastic trim. The reed switch is attached to the inside with a piece of Scotch tape. The ohmmeter is connected to each side. The magnet is attached to the ohmmeter with scotch tape and supported by the mono-filament line. The magnet is about 1/2” away from the reed switch and has successfully closed the switch- you can see from the ohmmeter that it is not an open circuit but has 14.6 ohms. This rather high resistance is probably due to my ratty old alligator clips, but even this is more than adequate to operate the relay shown in the PDFs, and get you on your way.

KILL SWITCH PAGE3.pdf

kill switch page1.pdf

kill switch page2.pdf

[RPM 1,232]

Thank you Terry! I don't think I've ever looked at this How To forum. 

[Mach1 Driver 584]

4 hours ago, RPM said:

Thank you Terry! I don't think I've ever looked at this How To forum. 

You should stop by more often Bob, there's some good stuff over here. 

[Midlife 831]

Bob needs to be able to read first...maybe he needs new glasses. 

As for the ultimate kill switch, I thought you meant something like this:

[Ridge Runner 1,146]

You would put your eye out 

[RPM 1,232]

19 hours ago, Mach1 Driver said:

You should stop by more often Bob, there's some good stuff over here. 

Ya, no kidding. Just read the AOD swap thread, from a guy who lives here in Bako! There's a bunch of info in there that I unfortunately had to learn myself. With all the google searching I did on AOD swaps, not once did the thread here in the How To forum show up. And again, I'm a day late and a dollar short. 

[danno 128]

I just posted an idea in the forum to take this a bit further. Use the windshield washer button to engage the relay instead of the magnet.  Mach1 Driver, if you know what I mean, can you post a revision to your schematic?   What did you use to draw your schematic?  Maybe I can make the changes?  It saves needing the magnet and reed switch.  It just requires you to know that you need to push the washer button every time you try to start the car. 

[Mach1 Driver 584]

9 hours ago, danno said:

I just posted an idea in the forum to take this a bit further. Use the windshield washer button to engage the relay instead of the magnet.  Mach1 Driver, if you know what I mean, can you post a revision to your schematic?   What did you use to draw your schematic?  Maybe I can make the changes?  It saves needing the magnet and reed switch.  It just requires you to know that you need to push the washer button every time you try to start the car. 

Here is your suggested revision, although it is not without its complications. I used two different CAD programs to draw the schematics. The first was Cadkey, and the second was Solidworks. Cadkey is an easy to use old 2D program, but it can't output to JPG, so I import it to Solidworks to clean up the fonts and export it as a JPG. Then I use Shotwell to resize the JPG, and post it on Imgur. I save the BB code and it appears as below:

Now on to the problems with the circuit:

1. I don't like the fact that there isn't a removable key (or magnet), but if that's your preference, then so be it.

2. As you can see, the washer pump is on fuse #1 which is connected to ignition switch A. The problem is that this contact is only ON in "Accessory" and "On". This means you would first need to turn the key to on (not start) and then push the wiper pump. This isn't too big an issue but it would be more convenient if you switched the pump to ignition switch C. Since the ignition circuit is not fused you would need to add a fuse.

3. AW Nuts!!!  I just noticed that I have B and C on the ignition switch reversed at pole C on the NO contact. C should be on the left and B on the right in the drawing. This is what holds the relay on. A further complication of this circuit is that a general purpose diode like one previously shown is needed. If you don't add the diode the washer pump will come on, and stay on, as long as the ignition is in Start or On.

[danno 128]

Yes, you understood exactly what I meant!  I know the diode was needed.  I figured B would go to the ignition ON, not start on.  But I can see you know what I am thinking.   I can see the complications you are mentioning, I just wanted to get the idea out there. 

I am not sure about the box with the dotted line at the lower left. It is not needed. Accy will work fine, as long as you are only doing the initial engagement of the relay.  When the key is turned to start, the ACCY power goes off, but by then the relay is engaged and held on my the NO contacts. 

I know about solidworks, I have not used the others you mentioned.  I have used Visio for schematics,  otherwise Cadence if it gets tied to a circuit card.  Too much of the time a pencil, paper, and a pdf scanner work perfectly well. Thank you for adding the schematic. 

Thanks.  I wonder if anyone else is following these details, or if anyone else cares? 

[aslanefe 342]

If I understood it right, if you use the washer button you have to have both hands on right side of the wheel; one hand to press the bottom and keep it pressed while you are cranking, other hand to turn the ignition. At least I will have a hard time doing that.

[smh00n 90]

Danno I'm following and I care. I want a kill switch that is stealth and this looks the goods.

I get the base idea but not the fine details. I just looked and all the bits I need are available here.

One question - if I hooked this into my Sniper and MSD ignition, would it affect either of them? As in, would either of those units 'know' their power was being interrupted? I am electric idiot so if I plugged this into the 12V feed that powers Sniper, it would cut both ignition and fuel as a default. If that is the case then I don't need to cut into either the fuel pump feed wire nor the power to the coil (??)

[RPM 1,232]

 I'm sure plenty are following. If not, I know the important people are :)

Edited May 3, 2019 by RPM

[Mach1 Driver 584]

9 hours ago, aslanefe said:

If I understood it right, if you use the washer button you have to have both hands on right side of the wheel; one hand to press the bottom and keep it pressed while you are cranking, other hand to turn the ignition. At least I will have a hard time doing that.

In this version, with the washer pump connected as usual, you would turn the key to ON (not start), press the washer for a second, take your hand off the washer and then turn the key to start. If you change the washer pump power source to ignition C and add a fuse, you could turn the key to "on or start" and push the wiper to engage the relay. Either way it only takes a fraction of a second to engage the relay and pole C will hold it on until the key is turned to off. When the relay is on the car will run.

[Mach1 Driver 584]

9 hours ago, smh00n said:

Danno I'm following and I care. I want a kill switch that is stealth and this looks the goods.

I get the base idea but not the fine details. I just looked and all the bits I need are available here.

One question - if I hooked this into my Sniper and MSD ignition, would it affect either of them? As in, would either of those units 'know' their power was being interrupted? I am electric idiot so if I plugged this into the 12V feed that powers Sniper, it would cut both ignition and fuel as a default. If that is the case then I don't need to cut into either the fuel pump feed wire nor the power to the coil (??)

The top of page 1 shows how to disable a MSD 6AL box. This method comes directly from their tech line. With the purple wire connected to ground the box will not fire, and it will not harm the box per their technician. This is their preferred method to disable the box. The bottom of page 2 shows how to disrupt the fuel pump. The EFI will not know the pump is off and won't care... of course it can't run without fuel. You don't need to do both but it doesn't hurt. I wouldn't cut the power going to the EFI- they are very finicky and require a line directly to the battery to eliminate all electrical noise. If you want a glitch free ride I would do it this way and leave the wiring to the EFI as they instruct. 

[danno 128]

Another minor complication with either the magnet or washer button idea is when someone else drives your car.  Suppose you take it in for a wheel alignment, the shop will need to be able to start the car and drive it.  So you need an override to temporarily disconnect the inhibit kill system to the car can be started and ran as usual.  I have a toggle switch in my trunk that allows the car to operate normally. 

More details to the schematic. 

 

[Mach1 Driver 584]

5 hours ago, danno said:

Another minor complication with either the magnet or washer button idea is when someone else drives your car.  Suppose you take it in for a wheel alignment, the shop will need to be able to start the car and drive it.  So you need an override to temporarily disconnect the inhibit kill system to the car can be started and ran as usual.  I have a toggle switch in my trunk that allows the car to operate normally. 

More details to the schematic. 

 

Read the last paragraph on page 3 above and review the schematic. Putting a switch in the trunk is a good alternative but I elected to go another way.