Introduction
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1.2 GLOSSARY OF TERMS
Term
Description
AVR
Automatic Voltage Regulator.
A device that automatically adjusts alternator excitation, to maintain the desired
generator output voltage and reactive power levels.
CAN
Controller Area Network
Vehicle standard to allow digital devices to communicate to one another.
CT
Current Transformer
An electrical device that takes a large AC current and scales it down by a fixed
ratio to a smaller current.
DM1
Diagnostic Message 1
A DTC that is currently active.
DM2
Diagnostic Message 2
A DTC that was previously active on the module’s internal memory.
DTC
Diagnostic Trouble Code
The name for the entire fault code sent by a J1939 CAN device.
FMI
Failure Mode Indicator
A part of DTC that indicates the type of failure, e.g. high, low, open circuit etc.
PGN
Parameter Group Number
A CAN address for a set of parameters that relate to the same topic and share
the same transmission rate.
PMG
Permanent Magnet Generator
A Generator that controls the alternator excitation voltage via a Permanent
Magnet type alternator (typically attached the shaft of the main alternator).
SPN
Suspect Parameter Number. A part of DTC that indicates what the failure is, e.g.
oil pressure, coolant temperature, turbo pressure etc.
