I am looking getting a simple Immobilizer/kill switch for my 95 Integra (I do not want a system with siren though).

Some shops offer a basic Immobilizer which is attached to an electrical accessory (flashers, turn signal, etc) and requires activation each time you start the car - This includes A flashing LED as well.

The other type I am considering comes with a unit attached to a key chain and the car will only start if this unit is within distance of the ignition, otherwise it will not start.

Any ideas/thoughts on these types of Immobilizers or other recommendations?

Thanks,
1995 Integra
146000km

 

If you are handy with wiring, you can add an immobilizer to your car dirt cheap. All you need are a couple of Bosch relays ($7 each) and a small toggle switch ($2 at Radio Shack, ask for a SPST switch). The most effective immobilizers cut off the power to the starter AND the ignition coil. That's why you need two relays. The idea is to interrupt the circuits that power the starter and ignition coil. You need to use relays since they can handle the high current requirements of these circuits. The small toggle switch is used to control the relays.

You'll have to find the starter and ignition wires on your teg. Both begin at the keyswitch and end up at your engine. The starter wire is a 12-gauge (somewhat thick) black wire with a white stripe. The ignition wire is a 12-gauge black wire with a yellow stripe. They are most easily found coming from the keyswitch on the steering column, or going through a plug on your under-dash fuse box. Go buy a test light and make sure these are the right wires before you cut them. The starter wire will be hot when the key is turned to the 'start' position, and the ignition wire will be hot when the key is in the 'on' or 'start' positions (don't probe the wires on any yellow connectors - you could pop your airbag).

Once you find the wires, you will want to make your cuts in a place a thief will not easily find them. Your wiring will probably not look too "factory," and a skilled thief might get around your handywork if she can find it. Once you have made this decision, hook everything up using this handy wiring diagram:


(link fixed 07/29/01)

A few notes. For safety, the fuse is very important. Don't skip it. Of course, you will want to find a good place to hide the switch so nobody will find it. The wire for the switch and ground connections can be thin (16-18 gauge). Also, in this configuration, your car will not start if the fuse blows. This gives you the ultimate protection, but might leave you stranded. If you are worried about this, use the 87 pins on the relays instead of the 87A pins.


[Modified by zilbotd, 10:14 AM 7/29/2001]

 

Good explanation. Two questions:

1. How many Amps do the relays need to be capable of handling?
2. How does the 87 pin differ from the 87A?

thanks

 

The standard black cube Bosch automotive relays handle 30 amps. This is sufficient.

Pins 87/87a differ in the following way. 87 is connected (inside the relay) to 30 when the toggle switch is off (no power to pin 85). When the toggle switch is on (power to pin 85), pin 87a is connected to 30.

 

zilbotd,

Thank you very much for the detailed explanation, I will think about attempting this. I can see by your message that you've done this more than once before!

Thank you!

 

what size of fuse should I use ?

I got everything wired in but the fuse..

thanks in advance, it'll work great..

 

A 5A fuse will work fine. The fuse is for the relay power supply, and the relays draw very little current. Sorry, I should have specified that in the original post.

 

thank you, I'll try it tonight

 

Do after market alarms also cut the blk/wht wire? IF they do, do you cut into it after the alarm wire or before thanks. Larry

 

Yes, aftermarket alarms cut the blk/wht wire. You can make your cut on either side of the alarm cut. You are interrupting the starter circuit, and you can do that anywhere along the length of the wire. The important thing is to do it where
a) it is not easily found
b) it is not easily bypassed

Aftermarket alarms with so called "starter kill" only cut the blk/wht (starter) wire. That is half the problem. We all know how to bump start a car without the starter (if the car has a manual transmission, of course), so a starter kill is easily defeated. But you car can not run without power to the ignition coil. That is why adding the second relay and cutting the ignition coil power is important.

The other problem with aftermarket alarms is that most are designed to make the car operable if the alarm malfunctions. That means that if the thief finds the alarm power supply, or worse, the brain, all she has to do is unplug it and the car starts. By wiring a kill switch in failsafe mode (using pin 87A), unplugging the power does not defeat the kill switch. It will not make your car theft-proof, but it will certainly make it more difficult to steal.

 

your graphic photo is down!~! Is there anyway you can draw me another diagram?

 

Hey that sounds simple enough ( ya right ) heehee, but the graphic would help a bunch..if someone could give me the graphic i'd appreciate it a bunch! since this was an old thread...

 

right click the image, goto properties and copy the URL, paste it into the browser and it comes up.........photopoint has some wacky problems with image hosting sometimes

 

oh! there ya go...thanks!

 

I changed the link to the graphic to a more reliable server. Sorry it took so long...

 

Actually, you got it backwards. In a standard 12volt Bosch relay, 87a is connected to 30 at rest (i.e. the switch is off - 85 and 86). When the switch is on 87 is connected to 30.

Using 87a for starter-kill is called normally-closed (low security) and using 87 is normally-open (high security).

 

For more detailed info and other 12-volt related stuff check out:
http://www.the12volt.com/relays/page2.asp

 

HondaDriver4Life, thanks for sharing that link!!

 

No problem. Check out the discussion board on http://www.carsound.com too. They've got some knowledgeable moderators who've been in the car audio industry for a while.

 

2 questions.

1) could you take out the fuse when you know the car will be sitting in a place for a while?

2) could you also hook one like this up to the fuel pump, to get a fuel cutoff as well?