WM_PRJ_M13_UGD_001 - 001
20th July 2004
© 2004
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Wavecom Confidential & Proprietary Information
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5.2 Specific recommendations when using the modem on
trucks
WARNING: the power Supply connection of the Fastrack Modem M1306B
must NEVER be directly connected to the truck battery.
5.2.1 Technical constraints on trucks
All trucks have a circuit breaker outside of the cabin. This Circuit Breaker is used
for safety reason: if a fire takes place in the trucks, on the wiring trunk for
example, the driver may cut the current source to avoid any damage (explosion).
This circuit breaker is connected to the truck ground, most often associated with
the fuse box.
Most of truck circuit breakers do not cut the Positive Supply line of the battery
but cut the ground line of the latter.
Because second hand installer prefer sometimes to connect directly the power
supply on the battery rather than on the circuit breaker, the Fastrack modem
may be damaged when starting the truck if the circuit breaker is switched Off (in
this case the truck ground and the battery ground will be connected through the
Modem as shown in the figure below).
M1306B
Figure 11: Example of electrical connection which may dramatically damage the
Modem