Navistar Electrical Systems CV
Integration Guide
Page 79 of 84
Revision Date: 9/12/2019
The main difference between AC and DC systems is that the voltage levels in DC
systems remain constant while the voltage levels in AC systems are constantly
changing. When measuring an AC system, it is important to know that the average
voltage is zero, and that is why A VOLTMETER SET TO DC WILL NOT INDICATE
THE PRESENCE OF AN AC VOLTAGE WHEN CONNECTED TO AN AC CIRCUIT!
High voltage can be lethal. Always refer to the manufacturer of the high voltage
component when maintenance or repairs are needed. In most cases, diagnostics and
repair are performed after the high voltage circuits are disabled. If working around or
maintaining high voltage circuits, please seek high voltage training.
WARNING - To avoid property damage, personal injury, or death, circuits must be
checked using a voltmeter for the presence of both DC and AC voltages. A
voltmeter set to DC will not indicate the presence of an AC voltage when
connected to an AC circuit! Contacting an unknown AC or DC voltage may cause
equipment damage, electrical shock, and/or electrocution.
Only a trained technician may perform service inside high voltage components. If
working around or maintaining high voltage circuits, please seek high voltage
training.
Understanding High Voltage Equipment and Circuits on International Products:
Some examples of high voltage equipment that can be encountered on products are as
follows:
—
Auxiliary Power Units (APUs)
APUs are basically small diesel-powered generator units that are integrated into the
vehicle electrical system. APUs are utilized in combination with inverters and battery
chargers. APUs are often set up to automatically start when the electrical management
system deems it necessary to maintain battery charge or electrical demand requires it.
NOTE - APU high voltage wiring may NOT be marked for easy identification as high
voltage.
—
Shore Power
Shore power is a connection from a vehicle to an external 120Volt AC power source.
The vehicle is equipped with an exterior receptacle that allows connection to an external
“shore” power source.
NOTE - High voltage shore power wiring may NOT be marked for easy identification as
high voltage.
