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AirLink MP User Guide
Note: Do not install an on/
off switch on the main (red)
battery line, or connect the
white ignition sense wire to
the red battery wire. Both
configurations bypass the
MP modem's controlled
shutdown sequence, and
may cause data loss and
subsequent power-on
problems. Incorrect wiring
may also drain the vehicle
battery.
26
The battery (red) and ignition sense (white) wires in the power harness include
5 A fuses. The black ground wire is not fused. (See
page 27.) Replacement power harnesses are available from Sierra Wireless.
Note: The battery cable used for a car, truck, or other mobile connection must be less than
3 meters in length.
Vehicle installation
This section applies to installing the MP modem in a vehicle. If you are installing it
in an office, see
Office installation
Ignition sense on/off wiring
This section only applies to installing an MP modem in a vehicle. If you are
installing the MP modem in an office building, use the AC/DC adapter.
The MP modem's power on/off is controlled by the ignition sense line (white wire)
using internal software, rather than a hard on/off switch on the red power line. The
red, black, and white wires connect to the battery and ignition switch as shown in
the power harness wiring diagram.
Note: The battery cable used for a car, truck, or other mobile connection must be less than
3 meters in length.
Switch (vehicle
ignition key, or
separate)
Vehicle battery
Figure 3-7: Wiring for the power harness.The white wire is the ignition sense.
•
When the white ignition sense line is pulled high (5 to 36 V), the MP modem
powers on.
•
When the ignition sense line is pulled low (less than 2 V), the MP modem
performs a controlled shutdown sequence (under software control), de-regis-
tering and saving any relevant operational data before powering off.
Ignition sense options
There are three ways to connect the ignition sense wiring:
Ground the power harness
on page 28.
Red wire
5 A fuses (on red
(Battery)
and white only)
Black unfused wire
White wire
(Ground)
(Ignition sense)
on
MP modem
2130795
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