car kill toggle switch

[linux44]

Hi Guys,
I am planning to install a kill switch on my car on the starter however I am not very good with electronics and ... , I have done an extensive research and here is where i am at :

1. I understand that my starter motor probably would want a high amper such as 70amp or so.
2. the starter can not be directky wired as if this was to happen a huge and think wire should have been wired form the starter barrel to the starter thus a thinner, smaller size cable is wired to a relay . the relay is then directly connectd to the starter using a high current cable. when i start the car the relay is switched on by the thin cable and thus current flows through the starter thick cable and hence engine start.

3.if i am to install a switch , i can do it by cutting the wire on the ignition barrel and connect each side of it to one side of the key and then the key will disconnect or connect them. My understanding is that i do not need a relay in here again as the amp should be low and acceptable,

4. my problem now is to find the right cable for my case for which i need to find the amp or the current that goes through the cable. from my understanding one way of doing this is by disconnecting the ignition wire on the barrel and then connect each side of it to my multimeter and then turn the starter key whereby i should see the amp flowing throught it . my understanding is that the positive lead should be on the output wire .
I have also heared that if the current is more than my multimeter amp power, i can fry my multimeter. mine has a rating of 10 A, does that mean i can do the test?


5. do u think i need a fuse or ... ?
I appreciate any answers from all memebers

 

[MarkieSparkie]

Hi Linux, Welcome to the forum. Kill-switches are usually wired to kill the ignition circuit, not usually the starter circuit. If you really want to kill the starter circuit, say with a hidden toggle or key-switch for security purposes, assuming this is the case then this what you need to do ...
Using you point 3 "i can do it by cutting the wire on the ignition barrel and connect each side of it to one side of the key and then the key will disconnect or connect them. My understanding is that i do not need a relay in here again as the amp should be low and acceptable,".
You are correct in what you say, except the special high current 'relay' is called a contactor.
Wire the kill-switch (toggle or key-switch) with some 14/0.30mm, 1mm[SUB][SUP]2[/SUP][/SUB], 8.75A rated cable available at most auto-factors or car parts store. It would be neater if you used pre insulated (red) crimps for your connections, either Lucar-blade or bullet type crimps are suitable, but it depends on type of switches you have.
You will probably find Lucar-blade terminals on your ignition switch, so by using this type of crimp, you can avoid having to cut into the existing wire. Just pull-off the existing wire and attached female blade from the ignition switch male terminal. Crimp a mating male blade on the end of one of your kill-switch wires and connect to this existing ignition switch wire female blade. On the other kill-switch wire crimp a female blade and push this on to the ignition switch male terminal.
You do not need fuse.

 

[Mark_Burgess]

If this is to immobilise your car, in all honestly, go get a professionally fitted immobiliser.

The reason is, the "kill switch" you want to put in, I suppose will be in reach of your driver seating area, so you can set it easy enough on the way in and out of the car? Any car thief that is determined to steal your will trash the steering column and will check for a switch if it does not start straight away. They will find the switch pretty quick.

With a proper immobiliser, all the wiring will be black and properly tucked away, this makes it a lot harder for them to take the car.

If you want to "kill the engine whilst running" follow the above post.

 

[ruston]

The first thing a car thief used to do on the older cars was to put all the switches in the opposite positions, then wreck the steering lock and use a screwdriver on the remaining ignition switch, then away. Modern cars are almost impossible to steal without the keys. If you want a simple immobilizer intercept the feed the to the starter solenoid and/or fuel pump, through a relay if you wish, or you could utilize a jack plug with your own configuration. Or has been said a professional one is the kiddy. Older cars are a target because as I have said it's very difficult to steal a modern one.

 

[Marvo]

Putting a kill switch on the supply to the solenoid just means they'll need to push start the car. I don't see this as much of a theft deterrent.

I would fuse any extra circuits you install, car wiring fires are very common and are usually caused by after market add on parts that are sloppily wired.

 

[linux44]

Hi Linux, Welcome to the forum. Kill-switches are usually wired to kill the ignition circuit, not usually the starter circuit. If you really want to kill the starter circuit, say with a hidden toggle or key-switch for security purposes, assuming this is the case then this what you need to do ...
Using you point 3 "i can do it by cutting the wire on the ignition barrel and connect each side of it to one side of the key and then the key will disconnect or connect them. My understanding is that i do not need a relay in here again as the amp should be low and acceptable,".
You are correct in what you say, except the special high current 'relay' is called a contactor.
Wire the kill-switch (toggle or key-switch) with some 14/0.30mm, 1mm[SUB][SUP]2[/SUP][/SUB], 8.75A rated cable available at most auto-factors or car parts store. It would be neater if you used pre insulated (red) crimps for your connections, either Lucar-blade or bullet type crimps are suitable, but it depends on type of switches you have.
You will probably find Lucar-blade terminals on your ignition switch, so by using this type of crimp, you can avoid having to cut into the existing wire. Just pull-off the existing wire and attached female blade from the ignition switch male terminal. Crimp a mating male blade on the end of one of your kill-switch wires and connect to this existing ignition switch wire female blade. On the other kill-switch wire crimp a female blade and push this on to the ignition switch male terminal.
You do not need fuse.

Thank you MarkieSparkie, two questions,
WHen you say people normally kill the ignition , I think that is even a better ideas so even if the car is bump started , it will still not turn on as there are no ignitions ( correct ?) . if this is the case , where is the ignition wire normally located, ( i don't think it is on the barrel ) . I have a manual and can find the exact wire once I know where to look for it.
One thing with this is that, once the car is on , there is always current going to go through the wire which means if for any reason it fails , the car will turn off correct ? this can be a bit dangereous.

finally I have heared that adding a wire of circuit can vary the volatge or something which can trigger an engine check or cause the ecu to behave strangly , is that correct ?

btw, I am not familiar with wiring sizes , what is a different between 14/0.30m or 1 mm.. I guess rephrasing my question, what is 14, is it just a name or 14 cm , inch or .. .

thanks again

 

[linux44]

Hi Ruston,
I did thought of fuel relay cut off but then was caustious not to cause any extra load on the wire so it triggers an engine light or throw a fault.

i think my fuel system has already got a relay, do i need a 2nd one if I was gonna do that ?
what would be a benefit of jack plug? does it have anything that for example normal crimps don't have ? or its just because it is easy to pull out and in thus not needing a switch

 

[ruston]

That was an example to be used instead of trying to intercept the the starting current and to be used in conjunction with Markies post, I should have made myself clearer. Having said that that thieves do'nt hang about if it dose'nt go they tend to leave them. I've recovered loads of abandoned attempts at thefts from cars etc.

 

[linux44]

That is the only thing i am worried a bit, which is either fire or engine light, do u know why it happens and whether a fuse or relay is more suitable for the case?

 

[ruston]

I will get back to you later on how to do that if you want. The jack plug is just used as a connection to trigger a relay and as you say you wont need a switch. You need to say what type of car this .

 

[linux44]

That would be great if you had the time to explain it to me , before that It will be interesting to know what will be its advantage compared to toggle switch

 

[ruston]

Sent you a PM.

 

[linux44]

Thanks, much appreciated.

Does anyone know of any good resource which can I can read to have an idea of car electronics, for instance how to find ground , positive, wire a relay or wire a fuse or just do the jack plugging as ruston kindly mentioned.

I prefer websites as there are no costs involved and no need to buy a book

 

[MarkieSparkie]

Hi Linux, 14/0.3mm, 1mm[SUP]2 [/SUP]... means 14 individual strands of copper wire each 0.3mm diameter combined to give a flexible cable of 1mm[SUP]2 [/SUP]cross sectional area.
You can access the ignition wire at the ignition switch; distributor; electronic ignition unit; or electronic control unit. Which is easiest will depend on the age of you vehicle.
For a reliable source of vehicle wiring products follow the link:
http://www.vehicle-wiring-products.eu/VWP-onlinestore/home/homepage.php

 

[MarkieSparkie]

Hi Linux, For good books covering automotive electrical and electronics basics in an easy to read manner follow the links:
http://www.amazon.co.uk/Haynes-Manu...=sr_1_6?s=books&ie=UTF8&qid=1317431384&sr=1-6
The Haynes Car Electrical Systems Manual: Amazon.co.uk: Martynn Randall: Books
http://www.amazon.co.uk/Automotive-...=sr_1_1?s=books&ie=UTF8&qid=1317431384&sr=1-1

 

[MarkieSparkie]

Hi Linux, Take a look at the following website, it may help.
Electrical System

 

[MarkieSparkie]

Hi Linux, Thought you may find this useful:

Vehicle Cable Ratings and Uses.​

Notes:-
1) Wiring carrying an electrical "load" will experience a small rise in temperature. For this reason, wiring is often rated in amps using the phrase "for continuous use."
2) The first number in the wire grade column refers to the number of strands of wire. The second number refers to the thickness of each strand in thousandths of an inch. The following table gives some metric equivalents.
3) Use these sums to work out current and power:-
Current (I) = Volts (E) / Resistance (R)
Power (W) = Current (A) x Volts (E)
Current (A) = Power (W) / Volts (V)
For example, a 55 watt headlamp will draw 55/12 = 4.59 amps. (Remember, you will have 2 headlamps in the circuit!) Fitting a 75 watt headlamp would increase the current drawn to 75/12 = 6.25 amps

Wire diameter	Wire cross-section	Continuous Current Rating / Uses
9 / 0.30 mm	0.65 sq mm	5.75 amps - Side lamps, tail lamps, reversing lamps, horns, etc
14 / 0.30 mm	1 sq mm	8.75 amps - Side lamps, tail lamps, reversing lamps, horns, general wiring.
28 / 0.30 mm	2 sq mm	17.5 amps - Headlamps, fog/driving lamps, windscreen wiper motor etc.
44 / 0.30 mm	3 sq mm	27.5 amps - Charging cable, battery feed, etc
65 / 0.30 mm	4.5 sq mm	35 amps -Charging cable for alternator, dynamo, etc
84 / 0.30 mm	6 sq mm	42 amps - Charging cable for alternator, dynamo, etc
97 / 0.30 mm	7 sq mm	50 amps - Heavy duty alternator, etc.
120 / 0.30 mm	8.5 sq mm	60 amps - Heavy duty alternator, etc.
80 / 0.40 mm	10 sq mm	70 amps - Heavy duty alternator, etc.
37 / 0.71 mm	15 sq mm	105 amps - Starter/ Battery cable
37 / 0.90 mm	25 sq mm	170 amps - Starter/ Battery cable
61 / 0.90 mm	40 sq mm	300 amps - Starter/ Battery cable

 

[MarkieSparkie]

Hi Linux, Check this out! It's the best I can find at the moment.
CDX eTextbook free online automotive textbook and encyclopedia

 

[linux44]

You are really a star.
loads of information in here . I really appreciate it thank you