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Sierra Wireless MP 875 Modem User Manual

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MP875 Modem User Guide

34 2130808

—or—

Note: If you choose to install a

separate switch, it must be

connected to the white ignition

sense wire, not the red battery

wire, so that the MP modem can

perform a controlled shutdown,

as described on page 32.

• Separatelyswitched.Connectthewhiteignitionsense

wiretoaseparateswitchmountedinaconvenient

location,whichallowstheMPmodemtobeturnedonor

offregardlessofthepositionoftheignitionkey.Inthis

configuration,theMPmodemcanbepoweredonoroff

evenif

thekeyisnotintheignition.

TheMPmodemalsohasa“PowerOffTimer”.Whenpoweris

removedfromtheignitionsensewire,theMPmodemremains

onfortheperioddefinedbythePowerOffTimer,uptoa

maximumof240minutes.ThePowerOffTimerisconfigured

in3GWatcher.Seetheonline

helpin3GWatcherfordetails.

Ground the power harness

Youmustconnecttheblackgroundwirefromthepower

harnesstothegroundednegativeterminalofthevehicle

battery,oranotherappropriateelectricalground.Failingto

groundthepowerharnessproperlymaydamagetheMP

modem,maycauseradiointerference,andcanbedangerous.

(

See“GroundtheMPmodem”onpage28.)Thegroundwire

intheMPmodempowerharnessisnotfused.

Power connections

ConnectingtheMPmodem’spowerwiresproperlyis

important—poorconnectionscandamagethewiring,theMP

modem,orthevehicle’selectricalsystem,andcanbe

dangerous.

Note: Ensure that all wires are

correctly spliced or crimped.

Improper grounding and wire

connections may lead to

equipment damage or safety

hazards.

Correct wire splicing

Youcansplicethewiresofthepowerharnesstothecarwiring.

PropersplicingisessentialtoreliableoperationoftheMP

modem.DoNOTuse“quicktaps”;theyreducetheintegrityof

thewirethatiscutandletmoistureintothecable.

Anappropriatemethodofsplicingistostripasmallportionof

theinsulation,solderthewirestogether,thenheat‐shrinkthe

connectiontore‐insulateit.

Crimp terminals

Ifsuitableterminalconnectionpointsareavailableonthe

vehicleforpowerandignitionsense,thenusingautomotive

crimpterminalsisrecommended.Whenusingcrimp

terminals,donotleavebarewireexposed.Donotuseacrimp

terminalformorethanonewireunlessitisdesignedforthat

purpose.

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