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Re: Theft deterrent

To: MACHWIL@aol.com
Subject: Re: Theft deterrent
From: Theo Smit <theo.smit@dynastream.com>
Date: Wed, 24 May 2006 22:16:48 -0600
Interesting... but they kind of play fast and loose with terminology 
with statements like "we create an open ignition circuit that disables 
the starting circuitry at the starter".

The starter doesn't run the car. A relatively light manual-transmission 
vehicle such as the Tiger, can easily be push started once you bypass 
the ignition switch. Therefore, the only true security mechanism is to 
disable the fuel pump, and/or the ignition itself, if the car is not 
started properly. You can do that in a couple of ways. The powerlock 
website pooh-poohs ignition and fuelpump bypass relays. That's 
understandable, since a piece of jumper wire can easily bypass the 
relay. But what if you took the opposite approach? You wire in a circuit 
that uses a relay to ground out the fuel pump if the alarm is triggered. 
Now, anyone that triggers the alarm prevents the fuel pump from 
operating. If they do bypass the ignition key and get 12 volts onto the 
fuel pump circuit, they blow whatever fuses are inline to the fuel pump, 
further compounding their problem. If the fuse(s) are located in an 
unconventional place, then the would-be thief is going to have a hard 
time quickly solving that problem.

Another approach is to use an authentication system integrated into a 
vital part of the engine controls. Suppose you use an MSD or similar 
ignition controller. It includes a feature where grounding the unused 
ignition trigger wire disables the ignition. I'm sure that any 
knowledgeable thief knows about that and may attempt to circumvent any 
obvious use of that feature, but it is possible to integrate a wireless 
receiver onto the MSD box such that it will only un-ground that wire if 
the receiver is receiving coded messages from a short-range transmitter 
that you carry on your person. With the whole thing built into the MSD 
control box, there is nothing external for the thief to work on unless 
he brought his own MSD box to replace yours.

Theo




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