snopes.com Post new topic  Post a reply
search | faq | forum home

  next oldest topic   next newest topic
» Hello snopes.com » Archived Forums » Automobiles Archive » Defeat alarm with 9-volt battery

 - UBBFriend: Email this page to someone!    
Author Topic: Defeat alarm with 9-volt battery
snopes
Return! Return! Return!


Icon 401 posted      Profile for snopes   Author's Homepage   E-mail snopes       Edit/Delete post   Reply with quote 
Comment: Just a quick one I've heard recently that I didn't see on your
site. That using a 9 volt battery against a metal body panel of a car can
short out the alarm and thus make it easier to steal. Not sure how big
that rumor is.

Posts: 36029 | From: Admin | Registered: Feb 2000  |  IP: Logged | Report this post to a moderator
Jason Threadslayer
Let There Be PCs on Earth


Icon 1 posted      Profile for Jason Threadslayer     Send new private message       Edit/Delete post   Reply with quote 
Electricity follows the path of least resistance.

--------------------
All posts foretold by Nostradamus.

Turing test failures: 6

Posts: 5481 | From: Decatur, GA | Registered: Nov 2002  |  IP: Logged | Report this post to a moderator
ilwrath
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
Well, you'd have to find a spot to stick the battery that isn't painted or corroded, as I doubt that a pocket 9 volt has enough power to overcome those to get a current TO the bodywork. And, after that, the bodywork is connected to the chassis, which is connected to the 12 volt ground on the car battery. I'm not really sure what touching a mini 9 volt battery is supposed to accomplish against all that.
IP: Logged | Report this post to a moderator
RoofingGuy
The First USA Noel


Icon 1 posted      Profile for RoofingGuy     Send new private message       Edit/Delete post   Reply with quote 
Maybe the sight of the approaching 9-volt scares the alarm into shutting down, sort of possum-like?
Posts: 724 | From: Ontario, CAN | Registered: Jan 2005  |  IP: Logged | Report this post to a moderator
ilwrath
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
quote:
Maybe the sight of the approaching 9-volt scares the alarm into shutting down, sort of possum-like?
[lol] Perhaps sticking the 9-volt to the car's tongue would be more effective?

[homer]mmmmmmmm.... tingle-ly[/homer]

ETA: fixed Homer tags. [Razz]

IP: Logged | Report this post to a moderator
RoofingGuy
The First USA Noel


Icon 1 posted      Profile for RoofingGuy     Send new private message       Edit/Delete post   Reply with quote 
quote:
Originally posted by ilwrath:
[lol] Perhaps sticking the 9-volt to the car's tongue would be more effective?

Well, obviously. [Big Grin]

Just so hard to get a car you don't know to stick its tongue out.

Posts: 724 | From: Ontario, CAN | Registered: Jan 2005  |  IP: Logged | Report this post to a moderator
mgbdriver
Little Sales Drummer Boy


Icon 1 posted      Profile for mgbdriver     Send new private message       Edit/Delete post   Reply with quote 
All that's going to do is make the hand that's holding the battery very warm.

mgb "I can start a campfire with steel wool and a 9-volt battery" driver

--------------------
"Chuck E. Cheese called. They want their band back."

my blog
Help me clean my basement!

Posts: 2717 | From: Michigan | Registered: Apr 2004  |  IP: Logged | Report this post to a moderator
Pigman
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
My guess is more along the lines that all you could expect is to make a otherwise good battery worthless.
IP: Logged | Report this post to a moderator
lawguy
We Three Blings


Icon 1 posted      Profile for lawguy   Author's Homepage   E-mail lawguy   Send new private message       Edit/Delete post   Reply with quote 
I don't know, sounds like it could work....if the car has Lucas electrics.

--------------------
"I've argued in front of every judge in this state, often as a lawyer."

Posts: 1021 | From: Northwest Indiana | Registered: May 2004  |  IP: Logged | Report this post to a moderator
BoKu
Happy Xmas (Warranty Is Over)


Icon 1 posted      Profile for BoKu   Author's Homepage   E-mail BoKu   Send new private message       Edit/Delete post   Reply with quote 
quote:
Originally posted by lawguy:
I don't know, sounds like it could work....if the car has Lucas electrics.

... and Smiths guages, Girling brakes...
Posts: 2079 | From: California | Registered: Feb 2000  |  IP: Logged | Report this post to a moderator
mgbdriver
Little Sales Drummer Boy


Icon 1 posted      Profile for mgbdriver     Send new private message       Edit/Delete post   Reply with quote 
quote:
Originally posted by lawguy:
I don't know, sounds like it could work....if the car has Lucas electrics.

Don't be silly. If the car had Lucas electrics, the battery would start leaking oil. [Big Grin]

--------------------
"Chuck E. Cheese called. They want their band back."

my blog
Help me clean my basement!

Posts: 2717 | From: Michigan | Registered: Apr 2004  |  IP: Logged | Report this post to a moderator
defrostmode
I'm Dreaming of a White Sale


Icon 101 posted      Profile for defrostmode   Author's Homepage   E-mail defrostmode   Send new private message       Edit/Delete post   Reply with quote 
That doesn't work, but if you hold the battery against your cellphone it'll unlock your doors!

[fish]

Posts: 34 | From: Colorado | Registered: May 2004  |  IP: Logged | Report this post to a moderator
lawguy
We Three Blings


Icon 1 posted      Profile for lawguy   Author's Homepage   E-mail lawguy   Send new private message       Edit/Delete post   Reply with quote 
quote:
Originally posted by Taxi mgbdriver:
quote:
Originally posted by lawguy:
I don't know, sounds like it could work....if the car has Lucas electrics.

Don't be silly. If the car had Lucas electrics, the battery would start leaking oil. [Big Grin]
Ah, that comment was meant for you.

--------------------
"I've argued in front of every judge in this state, often as a lawyer."

Posts: 1021 | From: Northwest Indiana | Registered: May 2004  |  IP: Logged | Report this post to a moderator
Hakuna Matata
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
A new "technique" used to steal cars in South Africa is to unscrew one of the car's light lenses, and insert 24V directly onto one of the light bulb sockets. This blows almost all of the electricity, including the imobiliser and satellite tracking device.

A 9V battery will have absolutely no effect.

Marc

IP: Logged | Report this post to a moderator
jsbumed
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
With the way car electronics are wired, not a chance with a 9V battery. If this were the case, I would be using this everytime I unlocked a customer's car.

Joe

IP: Logged | Report this post to a moderator
SkipF
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
quote:
Originally posted by Hakuna Matata:
A new "technique" used to steal cars in South Africa is to unscrew one of the car's light lenses, and insert 24V directly onto one of the light bulb sockets. This blows almost all of the electricity, including the imobiliser and satellite tracking device.

A 9V battery will have absolutely no effect.

So now you have a car with absolutely NO electronics.
You still have to 'force' your way into the car,
break the steeringwheel lock so
you can get the to steer AND YOU HAVE ABSOLUTELY
NO WAY OF STARTING IT SINCE THE ELECTRONICS ARE
WIPED OUT? The only thing left of any value are
the rims, tires and the tail light lenses.... I don't think so.
Another problem with that story...well, two things right now-
Are you going to go around with TWO car batteries to 'disable the car?',
and this one is a bit more technical- Since the
lights are off when you do this (I'm assuming...)
the only place the 24 volts goes is to the other
bulbs in THAT circuit. Perhaps you can wipe out
all four parking lights- but since the lightswitch is OPEN, the 24 V IS NOT going to
get into the electrical system. I don't think
that even 2400V would do that.

IP: Logged | Report this post to a moderator
Hakuna Matata
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
The MAIN purpose for destroying the electronics is to disable the tracking device before the car is stolen. The actual stealing is easy - just load the car onto a flatbed. Flatbeds, just coincidentally, and very conveniently have 24V batteries.

The majority of new, modern cars with computerised management systems have sensors in indicators and headlights and these require the lights to be connected to the management system even when the lights are switched off. BTW, the latest cars don't have a physical contact-type switch for most electrical items, rather thay use transistorised switches controlled by the computer, which don't take kindly to voltage, particularly if it's reverse polarity voltage.

IP: Logged | Report this post to a moderator
SkipF
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
quote:
Originally posted by Hakuna Matata:
BTW, the latest cars don't have a physical contact-type switch for most electrical items, rather thay use transistorised switches controlled by the computer, which don't take kindly to voltage, particularly if it's reverse polarity voltage.

That's NOT accurate. I pulled the headlight switch from my '04 Passat 4Motion and replaced it with an A6 switch. 100% mechanical. The wiring diagram shows brakelight going to other brakelight and 'centerbrake light'. Then switch
'F', a mechanical switch that goes fuse 31, then the battery. The ABS electronics ALSO has a switch that lives in the 'mastercylinder'. That one goes to the ABS computer. Reverse light has a mechanical switch 'F4' that goes to fuse 35 then the ignition lock and battery. Turn signal
goes to 'emergency light' switch (mechanical)then
'conveinence stalk', then battery.
Note2: Neither Passat nor M.B. ('96 E300) lens
covers are 'removable' from outside, without a hammer.
Bottom Line... THe more I look at power and MOSFET transistor data, the more your story sounds like a 'snopes'. PLEASE post a link or
two regarding your 'story'.
Thanks!

IP: Logged | Report this post to a moderator
Joseph Z
Xboxing Day


Icon 1 posted      Profile for Joseph Z   E-mail Joseph Z   Send new private message       Edit/Delete post   Reply with quote 
I doubt it truely myself that 9 volt battery put anywhere on your car's exterior will turn your alarm off at all.

Now a man (risking his freedom) can maybe contact the dealer or whoever installed the alarm in the vehicle and get a replacement unlocker and get into the car that way. Just can't turn on the engine in some cars without the key though.

Like my car Dodge Intrepid, you can start the engine with the unlocker I had installed, but can't play with the controls or the engine cuts off. Need the key to turn it on. [Razz]

--------------------
Joseph Z

Posts: 1356 | From: Woodbridge, VA | Registered: Jul 2004  |  IP: Logged | Report this post to a moderator
RushMore
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
quote:
Originally posted by Hakuna Matata:
Insert 24V directly onto one of the light bulb sockets. This blows the satellite tracking device.

The satellite tracker or terrestrial track would
be the LAST thing affected by 24 V through a bulb
socket. They are isolated from the cars electrical
system by a charging system that COULD be damaged
by 60 volts or more, BUT since these devises run
on backup batteries, and are turned ON by remote control,
sticking 24 volts through a lamp socket is a waste
of time. I also concur that MOST (if not ALL) lights are controlled through a relay if not electric switch AND most lens cover are removed from inside the hood/ trunk. The secondary from an
ignition coil might be a different story, but you didn't say that.

IP: Logged | Report this post to a moderator
Finite Fourier Alchemy
Markdown, the Herald Angels Sing


Icon 1 posted      Profile for Finite Fourier Alchemy   E-mail Finite Fourier Alchemy   Send new private message       Edit/Delete post   Reply with quote 
quote:
Originally posted by BoKu:
quote:
Originally posted by lawguy:
I don't know, sounds like it could work....if the car has Lucas electrics.

... and Smiths guages, Girling brakes...
Still, it might boil off the blinker fluid.

-A

--------------------
Thinking about New England / missing old Japan

Posts: 2603 | From: Virginia | Registered: Mar 2001  |  IP: Logged | Report this post to a moderator
ilwrath
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
quote:
The MAIN purpose for destroying the electronics is to disable the tracking device before the car is stolen. The actual stealing is easy - just load the car onto a flatbed. Flatbeds, just coincidentally, and very conveniently have 24V batteries.
I'm agreeing with some of the other posters here. I'd like to see a source for that. Most chassis lighting circuits are isolated by relays.

And, if you're going to pick up the vehicle with a truck, why not just skip the entire blowing of electronics? Get an enclosed truck, rig up a bit of mesh in the box to act as a makeshift Faraday Cage... Pick up one undamaged car with little risk of the satellite tracking system recieving the signal to activate.

IP: Logged | Report this post to a moderator
jsbumed
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
quote:
Originally posted by Hakuna Matata:
The actual stealing is easy - just load the car onto a flatbed. Flatbeds, just coincidentally, and very conveniently have 24V batteries.


This is not true of all flatbeds, none of our trucks have 24V batteries in them....multiple batteries yes, but no 24V. Also, I don't know how it is in your town, but I know every flatbed truck in mine. They are all owned by other towing companies. I'm not sure how many car thieves have access to rollbacks.
IP: Logged | Report this post to a moderator
Spicyitalian
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
quote:
Originally posted by lawguy:
I don't know, sounds like it could work....if the car has Lucas electrics.

Oh come now, I have never had problems with Lucas electrics. The problems were always with the previous owner's problems with Lucas electrics.

9 volt to body of car, will do nothing. Nada. Nil. Zippo. Zilch. If you're lucky enough to get contact with the metal, you'll short out your 9 volt, but that's about it. Negative earth or positive earth wouldn't have an effect either. Some people will say anything...or worse yet, believe it.

IP: Logged | Report this post to a moderator
KeithB
The Red and the Green Stamps


Icon 1 posted            Edit/Delete post   Reply with quote 
Um, if the headlights are off, then no current can flow to any other part of the car since the relays are open. You can probably put 1000 V there with no ill effect other than blowing out the other headlight. 8)
IP: Logged | Report this post to a moderator
   

Quick Reply
Message:

HTML is not enabled.
UBB Code™ is enabled.

Instant Graemlins
   


Post new topic  Post a reply Close topic   Feature Topic   Move Topic   Delete topic next oldest topic   next newest topic
 - Printer-friendly view of this topic
Hop To:


Urban Legends Reference Pages

Powered by Infopop Corporation
UBB.classic™ 6.7.2