Adding cut off (kill) switch to your Accord

[Vanilla Sky]

In reference to the How to http://www.3geez.com/forum/how/101555-adding-cut-off-kill-switch-your-accord.html

4 common places for kill switches are : Battery, fuel pump, i starter and ignition.

1. Battery kill switch - typically seen on track cars, cuts all supplying voltage to the vehicle. Switches are robust and heavy duty. Schematic attached shoes this circled in red.

2. Fuel Pump - One of the most common points to install a kill switch on an electrical fuel pump system. Easy being it can be well hidden and low voltage.

3. Starter - Another very common point seen in older carb'd vehicles, or vehicles with mechanical fuel pumps. Severing power supplied to the motor , inductor side of the starter solenoid, or connection leading to ground will work. Various suggested points are circled in orange.

4. Ignition - Common kill switch design even seen on IC engines. Highly common and highly suggested practice is to sever power to the primary low voltage side of the ignition coil though the positive or negative side terminals. To keep things simple, cutting power to the primary prevents the secondary side from generating high voltage. It is HIGHLY advisable NOT TO install a switch on the secondary side. Leaving the secondary side open circuited can cause high voltage buildup inside the coil and can cause the coil to self destruct. Shorting the secondary side provides a low resistance pathway to ground, giving a good potential to have feedback to the primary circuit. This can cause electrical and / or fire hazards. Suggested kill switch placement is circled in yellow.
Also relay's can be very useful for "circuit protection"


http://www.3geez.com/forum/attachments/how/6278d1402368367-adding-cut-off-kill-switch-your-accord-10353308_10100451821827546_1190900456719843167_o.j pg

Thank you Dave Lawrence, gp02a0083 on 3geez, for the how-to.

[lostforawhile]

you can ground the coil primary negative terminal and the coil will never fire, this is an old trick, the coil requires an interruption of the negative for the field to collapse, the ignition module wont care either, as all it does is switch the ground to that terminal. if the coil negative is grounded somewhere else is has no effect on the module as it's just interrupting the ground to that anyway, the coil has positive 12 volts constantly when the key is on, the module interrupts the ground, this causes the field to collapse, and induce the voltage in the secondary, if the ground becomes constant, the coil will just sit there like an electromagnet and not do a thing

[Hazwan]

Why bother risking to fry the ignition module and the coil itself by doing that?

[gp02a0083]

Thanks for correcting your information from the face book page regarding putting a kill-switch on the secondary side of the coil :hsugh:. However it appears that a bit more clarification will be needed in regards to inductors, ignition coils, and schematic readout/placement of switch to resolve this issue. An ignition coil acts as a "dual inductor" or transformer, the primary side can be broken down to a resistor-inductor or RL circuit , but combining both sides it can be modeled as a step up transformer. It is the flow of CURRENT that generates a change in the magnetic field (EMF and back EMF), the interruption signal from an ignition module(power transistor) facilitates cycling of the dwell time (on state).

With the suggestion made by Lostforawhile to ground the negative side of the coil is not exactly a wise idea. This provides a low resistance closed circuit allowing current to flow through the primary side due to an excessive ON state. While in this state high voltage will not be generated, however overheating of the primary side of the coil will result and potential misfire issues can occur, not making this an ideal / adequate solution.

As mentioned in the original post a simple single throw single pole switch can be installed in series with the Black / Yellow1 that is able to create a break /open wire as seen circled in yellow at the top and bottom of the original schematic image. Opening the circuit at this point will not energize the primary side of the coil and also disable the igniter unit effectively. For the Carb'd guys this also disables the fuel pump via blue signal wire that energizes the fuel cutoff relay.

[derolph]

Generally, what are the reasons for installing a kill switch?

[gp02a0083]

mainly it is for an anti-theft. Also by installing a kill switch possibly can give you a little price cut on your car insurance. Progressive lists my kill switch as anti-theft tier 1.

[lostforawhile]

Why bother risking to fry the ignition module and the coil itself by doing that?

the ignition module only switches the ground, it doesnt care if the coil is grounded or not, it wont hurt it, I would think the coil might overheat, but people have done this for years without issue, the idea here to confuse the heck out of the guy trying to steal your car, if they burn out the coil, the car sure isnt going anywhere, i would rather buy a coil then try to replace a car, I wish they still made that dragon smoke module, if someone tried to steal your car, it determined by logic if they were actually in the car, and it released huge clouds of colored non damaging smoke, no thief would stick around for that

[lostforawhile]

ha, they have another version of the dragon for your car, this is probably the most effective trick to run off a thief, no one pays attention to an alarm, everyone pays attention to a car with smoke billowing out, no thief is going to stick around with this going on , I think they said it can run up to 15 minutes 12V DC Car Security Smoke Screen (http://www.smokemachines.net/buy-car-smoke-screen-security-system.shtml)

[gp02a0083]

yet again your logic in general makes me question creditability. Redirecting topics and deleting posts like on face book are really good ways of showing this. The whole James bond smoke screen garbage is just plain retarded and most likely will piss the thief off more and possibly cause more damage. If you want to throw gimmick shit into a car put a high decibel / frequency siren in there to disable and hurt the thief's eardrums. Ultimately a well placed and hidden kill switch will work and is a cheaper, more effective solution than gimmick anti-theft devices.

[lostforawhile]

yet again your logic in general makes me question creditability. Redirecting topics and deleting posts like on face book are really good ways of showing this. The whole James bond smoke screen garbage is just plain retarded and most likely will piss the thief off more and possibly cause more damage. If you want to throw gimmick shit into a car put a high decibel / frequency siren in there to disable and hurt the thief's eardrums. Ultimately a well placed and hidden kill switch will work and is a cheaper, more effective solution than gimmick anti-theft devices.
thats been a round for a long time under a different name, and it works, I know people who have had them and it's made thieves run off, they have been in trucks dealing with money for years, this is just a smaller version for cars, it's well proven, thief will never stick around when a car gets that much attention, last thing he wants

[gp02a0083]

They have dye packs for money not smoke...... anyway thanks for steering the thread off topic like you usually do

[Vanilla Sky]

The main point of this mod was that it wasn't going to damage the car if it were to be cranked. We aren't looking to cook coils.

Adding a security system is for another post altogether. If you'd like to discuss that, please feel free to make another post about it. This thread is about the how-to, not car alarms.

[cygnus x-1]

Ignition coils can and do burn out from being overheated. The Megasquirt ECUs have a setting that allows you to invert the polarity of the ignition output signal to support the many different types of coil driver modules in existence. Setting the polarity wrong has burned out many coils during the initial setup of the ECU due to having the coil primaries powered for an extended period of time. There are warnings in the docs about making sure this setting is correct before you begin. It's also advised to have the coil disconnected during first power up if you aren't sure whether the setting is correct or not.

C|

[niles]

Wouln't a kill switch on the ignition switch output ("on" or "start" ) be sufficient for most people? I'm not a car thief, but if busting the ignition open was not enough to get the car started I would move on to the next car...

[Hazwan]

It should be but most people wanted/needed more. They could have bypassed it straight to the coil. Same goes with starter kill. They could push started the car. Or fuel pump kill where they would run a wire directly to the fuel pump. Do them all and they're gonna have a hard time figuring out which one is which and hopefully move on to the next target.

If they wanted your car bad enough then theres always a way, kill switches or not

[JohnBoy]

I have one on the fuel pump and it works great.

[3gmodifier]

My kill switch is kind of a hybrid. I have my starter wire completely de-soldered from the ignition switch due to my custom push button start. But whats more is I wired up my main power lead into the ignition switch with a relay in between. So when I have my hidden switch on, there is no power whatsoever going to the ignition switch. Even if you had my key you could turn it to the on position and nothing would happen. To dash lights, no radio, no nothing. It is like there is no battery in the car. I did this because with simple fuel cut style killswitches, if the car cranks but does not start, the theif is half way there. He will then know to look for/bypass either a fuel or spark related item. With my set up nothing at all works.

[3gmodifier]

And by the way. I added the relay to the power going into the fuse box on the back side and used spare factory wire so first off you can even tell that any new wires were added. Second even if you did know, you wouldnt even see them.

[niles]

That's pretty smooth 3gmodifier!

[Oldblueaccord]

That's pretty smooth 3gmodifier!

I have my main relay loose and just snag it if I am leaving my car someplace for a long period. I dont think any of the civic ones cross over so I figure Im pretty safe.