Group 30 Electrical System—VNL, VNM
Service Procedures
Connectors
Packard, AMP, JAE, KOSTAL and Deutsch connectors
are used throughout the electrical system. Refer to the
connector manufacturer’s literature for contact removal,
crimping and insertion instructions. Special tools are
required for these procedures. If contact removal is
attempted with an ordinary pick, there is a good chance
that the terminal will be bent or deformed. These terminals
must not be reused once they are bent.
Molded-on connectors require complete replacement of
the connection. This means splicing a new connector
assembly into the harness. It is important that the best
possible bond at all wire splices be made by soldering
the splices (see Soldering procedure).
Environmental connections are used to isolate termina-
tions from the environment. Environmental connections
must not be replaced with standard connections – only
with environmental connections. If a connector is replaced
with one having more cavities, the unused cavities must
be plugged to provide an environmental connection.
Use care when probing the connections or replacing ter-
minals in them; it is possible to short between opposite
terminals. If this happens to the wrong terminal part, it
is possible that damage may be done to certain compo-
nents. Always use jumper wires between connectors for
circuit checking. Never probe through seals or wire insu-
lation.
When diagnosing for possible open circuits, it is often dif-
ficult to locate them by sight because oxidation or terminal
misalignment are hidden by the connectors. Merely wig-
gling a connector or a sensor in the wiring harness may
correct the open circuit condition. This should always be
considered when an open circuit is indicated while trou-
bleshooting. Intermittent problems may also be caused by
oxidized or loose connections.
Steam Cleaning and Pressure
Washing
Do not steam clean or pressure wash electrical compo-
nents or wiring when they are disconnected or removed
from the engine. This can damage the components.
Dielectric Grease
The use of dielectric grease is encouraged for all plugs,
sockets and connectors. It reduces corrosion by providing
protection against moisture and the elements (see
Service
Procedures).
Add-on Electrical Equipment
The electrical system in the vehicle is designed to perform
under normal operating conditions without interference
from other components.
Failure to properly install additional electrical components
may adversely affect the operation of the vehicle, includ-
ing the engine, electrical charging system, truck body,
stereo system and the driver information systems.
Overloaded circuits are usually the result of an "add-
on" option being improperly installed. The most common
mistakes are:
•
Improper installation of the wiring
•
Poor terminal installation on the wire
•
Improperly protected by a fuse or circuit breaker
•
Overloaded circuits
Volvo GM Heavy Truck Corporation assumes no respon-
sibility for any adverse effect upon the vehicle or any of
its components or systems which may result from the im-
proper installation of additional electrical equipment which
was not supplied or recommended by Volvo GM Heavy
Truck Corporation.
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