The first place to check is always via the on board computer as in
modern cars they frequently monitor the amperage drawn by each light
bulb to log when a bulb goes bad, or when there is a faulty
connection. I prefer a MODIS with proprietary software for each manufacture.
The second is a DC current measurement off the main battery cable
(non-invasive clamp on high amps), and then tracing out the low amp
(non-starter side) to the main power distribution point, usually the
feed point just prior to the fuse panel. It is important not to ever
break the connection, so you start with a amperage draw over a 90
minute period. You are interested in what the current draw is both at
a fixed time, but also over time, so you really want to use a chart
recorder and record both the milli-amps of draw, and the voltage
present. It is also critical that you understand and isolate the high
amps circuit from the low amps circuit, and that you actually trace
the high amps wiring to see if an eavesdropper has tied into it to
steal a few mA. If an RF transmitted is hardwired it will
periodically spike the battery for a a fraction of a second (hint, if
the vehicle has Lo-jack it will spike 50-300 mA once every 60 seconds
with the vehicle is not moving). Be sure to have a shop manual
studied in advance so that you know how much each of the static devices draw.
You can also use either the low or high amperage wire between the
battery and fuse panel or between the battery and starter as a
current shunt. If you know the wire gauge, you can compute fractional
ohms per foot, and use a four lead ohm meter to measure voltage drop
over one ohm of wire. If you are really on your game, then you can
wrok this out base on the voltage drop over a tenth ohm of wire.
The third is to use an AC current adapter so that you can ***
inductively *** couple a spectrum analyzer and oscilloscope/chart
recorder into the primary battery circuit that gives you RF data
right off the battery cables (usually the ground side).
The fourth is to use a directly AC and DC coupling across every fuse
where you use the fuse and itself as a current shunt where you can
pull off a few millivolt per milli-amps (little known TSCM secret).
For a DC coupling you go across the shunt in parallel, and for the AC
coupling you go from each side of the shunt to ground (three paths on
each pseudo shunt. While this may seem like a bit of overkill it
simplifies locating precisely where the bug is in the vehicle in a
non-alerting fashion as you can figure out which side of the shunt
the eavesdropping load is located. There are little fuse adapters
that you can use to clip on the other blade fuses or tube fuses for
this kind of test. What ever you do, do not remove any fuse during
this part of the sweep (it is all non-alerting up to this point).
(Prior to this point nothing that you have done is of an alerting nature)
Fifth, you insert a battery into the vehicle (usually at the
cigarette lighter or fuse block), let both the auxiliary and vehicle
battery normalize, then disconnect the battery lead, and install a
hardwired current shunt right on the battery. Then reconnect the
battery vehicle battery. Optionally, you can clamp this onto the back
of the battery cable, lift the conenctor off the battery, instert the
shunt, and then reconnect.
Sixth, then repeat above for each of the loads on the fuse block
there you attach an alternate power source to each lead, let it
normalize, pull the fuse (or battery), and insert a current shunt
into each of the major circuits. The key is to ensure that anything
down-circuit from the battery always has power so that the radio,
PCM, or tracking device never looses power, but your get "vascular
access" into the wiring of the vehicle so that you can monitor
current draw, or RF activity on every major circuit.
Seventh, Observe the vehicle electronically for 90 minutes while not
moving, and then take it out for a 60 mile drive (30 miles each way),
and ensure that your drive includes areas of fringe cellular
reception, and areas where there will be zero GPS or other RF
coverage (tunnels, deep garages, etc).
If the customer is agreeable you can leave the shunts in place for
future "vascular access" during sweeps, and for executive limousines
or high security vehicles I recommend that the shunts be permanently
installed before the vehicle is ever placed into service.
Eighth, at the "end' of the sweep, remove the shunts in the reverse
order and methods that you installed them so that you never deprive
any circuit of power. This way the spy will never know that you have
worked on the vehicle, let alone performed anything like a bug sweep.
Of course you still need to check the vehicle in close detail for
anything of an RF nature, and perform a detailed physical inspection,
but this will give you some idea as to how to properly measure and
observe the AC and DC currents in a electrical system vehicle.
One other thing, folks please purchase a door switch bracket to
depress the plunger so that you do not run the batteries down, and
also so that you are not creating an electrical load just because the
doors are open. These brackets go between the door and the plunger.
If a client is asking you to perform a stand alone limited vehicle
sweep you are talking about 4 hours of vehicle contact time, or 12-72
hours for a more detailed inspection (involving pulling seats,
headliners, dash etc). The problem that we all run in to is the
client who can only give you 1 hour of access to the vehicle, or who
needs to have the sweep only involve checking for live RF devices
(ie: they are only interested in GPS trackers with a cellular link,
but not GPS logging systems).
Unless you are extremely comfortable under the hood of a vehicle (ie:
you can pull and rebuild an engine), and have a small fortune
invested in both automotive and electric tools then you have
absolutely no business performing vehicle sweeps.
-jma
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James M. Atkinson Phone: (978) 546-3803
Granite Island Group Fax: (978) 546-9467
127 Eastern Avenue #291 Web:
http://www.tscm.com/
Gloucester, MA 01931-8008 E-mail: mailto:jm..._at_tscm.com
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No enterprise is more likely to succeed than one concealed from the
enemy until it is ripe for execution. - Machiavelli, The Prince, 1521
Received on Sat Mar 02 2024 - 00:57:19 CST