disabling through antenna
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=21721
Printed Date: May 10, 2024 at 2:39 PM
Topic: disabling through antenna
Posted By: tonto26
Subject: disabling through antenna
Date Posted: November 20, 2003 at 5:26 PM
I was informed that theives can disable an alarm by using a jumper box, and running 12 volts through the cars antenna. If this is true, then how can it be prevented?
Replies:
Posted By: auex
Date Posted: November 20, 2003 at 5:35 PM
Haha, that sounds like a good way to do nothing. Even if they grounded the battery that they were using to "spike" the antenna with to the frame of the car, all it would do at most is blow out the tuner in the radio.
-------------
Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: tonto26
Date Posted: November 20, 2003 at 11:04 PM
I was wondering, because even though it seemed like a ridiculous idea, i thought it might be possible that it would end up sending voltage to the accessories of the car, causing the alarm to think it was running. As a safeguard I thought of maybe adding a diode to the accesory input of the alarm.
Posted By: auex
Date Posted: November 20, 2003 at 11:06 PM
Don't even worry about it, it can't do anything. Like I said the most it will do is blow the tuner section of the radio. Also even if it did send power to the accessories, and it won't, that will not help the thief disable the alarm.
-------------
Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: Teken
Date Posted: November 20, 2003 at 11:40 PM
Tonto26,
These are my thoughts and suggestions to your fears. I will not tell you exactly what area's of the vehicle need to be addressed, but will offer a few things you should incorporate into your system, if you want to be protected from these sort of threats.
These simple techniques will protect the alarm system, and those compoents that you require to be a deterrent.
The feed-back I am giving you is based on many years as a professional REPO man. Every alarm system I have encountered in 10 plus years all exhibit the same faults and no installer from California to New York has ever addressed these in a day to day installation.
Only those who I have spoken with, or shared information via forums such as these have had more chance of me not disabling their system in under 60 seconds.
This isnt an guarantee, that it wont be taken. If it takes us more than 3 minutes to deactivate the system from the time we say go.
I just simply tow it...
1) All outputs from the alarm CPU which interact with the vehicle system(s) should be fused. Stepped fusing is ideal.
2) Shunt isolated / voltage regulated power supplies powering the alarm will provide stable, and secure power source.
3) An isolated ground plane, also known as a floating ground. Will prevent ground loops, and feed-back.
4) Ferrite core beads placed onto critical wiring will reduce RFI interuptions.
5) A direct secndary *chassis* ground strap, that you see on most rear end of the vehicle's or similar placement will ensure a steady ground plane, and bleed off residue static discharge.
6) A powered back-up siren is a must, assuming any of the above is not in use. To provide a last line of defense, in alerting you or others of an attack.
7) As a last line of defense to a alarm failure, and to protect the vehicle from being taken (not from being towed though) is to ensure you have physical devices that are engine, fuel, ECU, etc switches / fuse(s) that must be activated to operate the vehicle.
Regards
EVIL Teken . . .
Posted By: atomsite
Date Posted: November 21, 2003 at 8:54 AM
Perhaps some transient protection could be added to the antenna cable. i.e. Gas discharge tube, thyristor, Metal-Oxide Varistor, etc Theoretically a high voltage spike could propagate through the 12 volt power bus via the radio. However I would think that would fry the vehicle electronics as well. Making it somewhat difficult to start. Obviously you want to fry the alarm electronics and not the vehicle. I would think the easiest direct access to the alarm would be via the parking lights. These are typically connected to the alarm for the blinking light affect. Again you would want to apply just enough of a surge/spike to take out the alarm and nothing else. Perhaps the alarms are already internally protected. Who knows because the manufacturer rarely gives out any usable specs.
Posted By: atomsite
Date Posted: November 21, 2003 at 8:57 AM
I doubt if 12 volts into the antenna would do anything. I was hypothesizing a high voltage surge into the antenna.
Posted By: 1kewlexpo
Date Posted: November 21, 2003 at 9:29 AM
A stun gun can shock the entire vehicle and disable the alarm system and mess up most of the vehicle's circuitry. It will disable the car and will be immobilized. This will enable the thieves to get in the vehicle and steal what they want including your wheels. They can't start it since most of the fuses are blown. But, they can steal parts of the car. A backup battery or siren doesn't help with this matter. John
Posted By: derek123
Date Posted: November 21, 2003 at 11:32 AM
not mentioning any names, but there are a few alarms that can disabled the way you mention.
Posted By: atomsite
Date Posted: November 21, 2003 at 4:04 PM
If they blow up the electronics at least they won't get the vehicle. Chances are it'll be an expensive repair though. You could isolate the alarm system from the rest of the vehicle electronics. (i.e. DC-DC converters, opto-isolators, relays, etc.) Then add in some transient protection. That would require some work though. I suppose a simple relay to control the parking lights would isolate the alarm. I only mention the parking lights because they are easily accessible. Theoretically you could do it on any of the inputs. However you would have to trip the alarm to access them. That's why I like those pager style alarms. You know right away if your vehicle is being violated.
Posted By: atomsite
Date Posted: November 21, 2003 at 4:06 PM
Hey, howabout shock & tow.
Posted By: auex
Date Posted: November 21, 2003 at 6:17 PM
Stun gun? That is almost as funny as the antenna part. If you use a handheld stun gun, it shouldn't do anything but eat up some of the paint. While a stun gun has enough current to "stun" people, a car is too big for it to have much of an effect if it is just applied to the outside or frame of the vehicle. A stun gun will in no way blow any fuses off of the alarm, unless they take it directly to the board of the alarm.
-------------
Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: atomsite
Date Posted: November 21, 2003 at 7:07 PM
Hmmm, maybe a BIG 50kV oil capacitor injected into the wiring. That oughta do something. If you worked in a junk yard and didn't mind frying a few cars you could experiment. (Be careful not to touch the terminals or you might be fried.)
Posted By: atomsite
Date Posted: November 21, 2003 at 7:17 PM
Posted By: auex
Date Posted: November 21, 2003 at 8:40 PM
Just curious, but what would happen if one of those caps was shorted, positive and negative terminals?
-------------
Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: atomsite
Date Posted: November 21, 2003 at 9:44 PM
Pretty much like when you short your battery terminals. A nice arc.
Posted By: atomsite
Date Posted: November 21, 2003 at 9:48 PM
Check out this one, I wonder if that would blow up the car!? Kinda bulky though. | Z20100 | 10KJ | 2MV | 20 | 100nf | 75KA | >1200Kg | $44,220.00 |
Posted By: Teken
Date Posted: November 22, 2003 at 12:21 PM
LMFAO...  If I told you what we use on the job to do the very same thing, you wouldnt believe me.
Regards
EVIL Teken ...
Posted By: 1kewlexpo
Date Posted: November 22, 2003 at 12:28 PM
auex, LOL. The reason I said that is because several kids did that around the valley to steal wheels from cars with alarms. They used some type of stun gun to shock the car and diasabled it. They didn't care for the cars, just the wheels and other accessories. It worked for them but it did do a lot of damage to the electrical components of the cars. John
Posted By: auex
Date Posted: November 22, 2003 at 1:01 PM
I still call bull.
-------------
Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
|