Mack V-MAC IV, Operator'S Handbook Manual, Page: 79 / 133

V-MAC Co-Pilot Operator's Manual 71
ELECTRICAL ACCESSORY CONNECTION POINTS
This MACK chassis is electrically ready for convenient installation of electrical
accessories. Use the designated battery post (+12 V), ground post, CB jack, buffered
RPM outputs, buffered mi/h outputs, and the SAE/ATA J-1708 post located on the
electrical equipment panel for the installation of any electrical accessories. Each
connection point is described below.
Battery Post (BATT)
This is a +12 volt, unswitched battery power connection. It can be used to power
external devices that require power at all times, even when the ignition key is turned
OFF. This source is protected by a 15-amp circuit breaker.
Ignition Post (IGN)
This is a +12 volt, switched battery power connection. It can be used to power
external devices that require power only when the ignition key is ON. This source is
protected by a 15-amp circuit breaker.
Ground Post (GND)
This is a ground connection. It can be used as a power return (−) connection for
external devices.
RPM Output
This is a 50% duty cycle, 5-volt transistor-transistor logic (TTL) compatible,
square-wave signal that is calibrated to provide a standard pulse rate of 12 pulses
per engine revolution.
Note: Transistor-transistor logic compatible of this output may be affected by other
devices connected to this output. Maximum rated current of the TTL output is 10
mA. Total current draw of all devices connected to this output must not exceed 10
mA at 4 volts.
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