MP875 Modem User Guide
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.
Note: Ensure that all wires are correctly spliced or crimped. Improper grounding and wire connections may lead to equipment damage or safety hazards.
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•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
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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