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Author: Subject: DIY immobiliser/security doohdad idea
Staple balls

posted on 9/3/04 at 03:09 AM Reply With Quote
DIY immobiliser/security doohdad idea

been thinking about security for locosts and came up with this idea for a bit of security.

basically it'll just be a female connector somewhere out of sight to cut a few important circuits, with a dongle/key (male connector) that acts as a bridge to make a few circuits live (and the car startable)



something along those lines (hope it's reasonably clear)

*BUT* rather than the 2 circuits and 4 connection plugs, using say, 3 circuits in a 10 connector plug, with all unused connectors in the plug containing dummy wires to make it near impossible to guess the setup.

unfortunately, it wouldn't be SVA compatable (could be used while engine running) so i'm considering maybe using a solenoid to lock everything together while the engine's running.

hope i'm making sense (first time for everything)

cheers
alex






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blueshift

posted on 9/3/04 at 08:02 AM Reply With Quote
perhaps you could just use it to cut the starter relay feed? if you use a 10-way connector with 10 wires the same colour going into it, it would still be pretty difficult to hotwire. If you wanted to be clever you could make it so that hooking up any of the other wires set off an alarm.

Using a solenoid to lock it sounds fiddly and prone to failure, to me.

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Julian B

posted on 9/3/04 at 08:16 AM Reply With Quote
Excelent idea.
Just a thought to try and make it sva complient , if you were to add a relay like the picture below the engine would stay running even if the immobiliser key was removed... ....

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Staple balls

posted on 9/3/04 at 12:21 PM Reply With Quote
cheers for the input

Julian, the relay etc sounds a good idea, should do the trick niceley.

like the alarm idea blueshift, i reckon that'd be easy enough to do, just require the same style gadgetry as julians idea to make it work well

[Edited on 9/3/04 by Staple balls]






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greggors84

posted on 9/3/04 at 02:04 PM Reply With Quote
For sva, cant the immobiliser turn off the engine. I was just going to use a hidden battery cut off switch for simplicity.

Stapleballs - would you be interested in making your self a bit of money and making a few of these. There was an idea a while ago about a diy keypad immobiliser but it never got anywhere.





Chris

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Staple balls

posted on 9/3/04 at 02:08 PM Reply With Quote
i'll have a look at it

but i'm not really too hot on this electrickery lark.


added you to my msn






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Deckman001

posted on 9/3/04 at 02:16 PM Reply With Quote
For SVA, you need to have a device that imobilises the car, ie a steering lock as fitted to the donor, or a battery cut off switch is ok, so the device being described here will be ok as it prevents the car being started and driven away

Jason






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Spyderman

posted on 9/3/04 at 03:23 PM Reply With Quote
quote:
Originally posted by Julian B
Excelent idea.
Just a thought to try and make it sva complient , if you were to add a relay like the picture below the engine would stay running even if the immobiliser key was removed... ....



Julian,
Not my strongpoint, but shouldn't the relay trigger be taken from the other side of the relay?
Otherwise it will be live all the time!

Terry






Spyderman

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Staple balls

posted on 9/3/04 at 03:37 PM Reply With Quote
just another thought

is there really any need for a relay? say, if we only cut the starter solenoid wire [B/BL] as far as i know that'd only stop the car from being started, and wouldn't affect it once running. which i *think* would fall inside sva rules






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Julian B

posted on 9/3/04 at 03:39 PM Reply With Quote
I dont think so

if you turn on the ignition without the immobiliser dongle the relay will not work.

When the dongle is inserted the relay fires and then it self latches until the ignition switch is turned off.

To restart you would need the immobiliser dongle again

. This idea can be taken one step further and instead of a simple hard wired dongle a digital signature system could be devised.
All you would need was two off the shelf chips, one for the dongle and one for the relay.
If the code in the dongle key matched the code on the relay then it would fire the relay.
You could probably make a simple system up for about £25ish.
Citroen used to use a very similar system in their remote central locking systems
Anyway i digress

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Staple balls

posted on 9/3/04 at 03:56 PM Reply With Quote
hmmm

got any info for the relay i'd need? a tad better diagram would help too

as for the chip etc, yep, that's a good idea, but a lot of hassle/effort, and a little too much techmagical

cheers






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greggors84

posted on 9/3/04 at 04:19 PM Reply With Quote
Just had a look at maplins for connectors and a plastic case, came across this;

Key Module

As it switches a relay, im sure it could be used for this method. Not too much for £25.

Staple balls, you havent been added to my msn for some reason?





Chris

The Magnificent 7!

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Staple balls

posted on 9/3/04 at 04:35 PM Reply With Quote
odd

i added you using the info in your profile and you appear in my list, just not online






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Julian B

posted on 9/3/04 at 04:38 PM Reply With Quote
Whats your donor vehicle and do you have the haynes manual wiring diagram?
If its sierra i will have a manual oher than that can you scan the page and upload it?


The relays you can buy for 3 or 4 quid from rswww.com. try part number178-2012 £3.89, Its a relay capable of switching one 30amp circuit.
Alternativley, most 4 or 5 pin relays from the scrappy can be used, idealy go for the high current ones that switch the headlight circuits. You will require one relay per circuit or if you are lucky you can get a multi pole relay but they are a bit difficult to get hold of.
The only other thing is to try and steer clear of putting a relay in the starter motor circuit becuse of the higher currents involved,

Hope that helps

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blueshift

posted on 9/3/04 at 04:57 PM Reply With Quote
ah, I knew there was something I could be doing at work to do with the car.. I was going to have a crack at a keypad immobiliser myself, PIC-based.

prob be awhile before anything comes of it, but if I get one working I would be happy to build more of them for people. I'll shout if I do.

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greggors84

posted on 9/3/04 at 05:09 PM Reply With Quote
Keep us updated blueshift, theres a customer here...





Chris

The Magnificent 7!

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MonkeyHunter

posted on 9/3/04 at 05:45 PM Reply With Quote
I have used one of these to make my retrofitted central locking / immobiliser a code hopping jib. It?s very easy to use, and if you can?t be bothered they sell ready built kits that you could probably adapt.

http://www.electronic-kits-and-projects.com/30a16.htm

Scott.

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stephen_gusterson

posted on 9/3/04 at 07:47 PM Reply With Quote
surely all you need is a hidden switch to the coil feed OR a switch to short across the circuit breaker.


atb

steve






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Staple balls

posted on 9/3/04 at 07:55 PM Reply With Quote
all you need maybe,

but that's hardly gonna stop a scumbag is it? takes all of 3 seconds to bridge a switch.

on the other hand a 10 pin plug, 8 of which are wired to an alarm is gonna cause some real hassle






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blueshift

posted on 9/3/04 at 10:15 PM Reply With Quote
quote:
Originally posted by greggors84
Keep us updated blueshift, theres a customer here...

Right you are. Somewhere I saw was selling a keypad with translucent keys and a blue backlight.. the idea of wiring that to light up when you put the key in, and how it would look at night, almost made me stain my pants.

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Julian B

posted on 9/3/04 at 10:20 PM Reply With Quote
well i agree with you both

The thing is only to make it difficult to start. if you have a theiving git who is also an electronics engineer the security system will only be as good as your electronics knowledge,
I managed to crack citroen's 65000 possibilities code system in about 1/2 hour ! and i was selling replacement fobs to the local garage fo £20 a go.
Hiding a switch is by far the best way to go ...but if you realy want to pinch a seven then 4 blokes and a trailer could pick it up and walk away with it.

Make it scream and make it difficult


Cheers

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stephen_gusterson

posted on 9/3/04 at 10:49 PM Reply With Quote
at the end of the day, all mr scumbag needs is a bit of wire. He can bypass all of the immobiliser stuff by just connecting battery to the coil +ve and getting his mate to push start the car......

there are ways around most things.

the grounded contact breaker would be subtle.....


atb

steve

[Edited on 9/3/04 by stephen_gusterson]






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greggors84

posted on 9/3/04 at 11:54 PM Reply With Quote
I was planning on just using a battery cut off switch, but this can be operated when the engine is running, which is a fail for SVA ive heard.





Chris

The Magnificent 7!

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blueshift

posted on 11/3/04 at 12:52 PM Reply With Quote
quote:
Originally posted by stephen_gusterson
at the end of the day, all mr scumbag needs is a bit of wire. He can bypass all of the immobiliser stuff by just connecting battery to the coil +ve and getting his mate to push start the car......


Not with EFI

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