Volvo VNL Service Manual page 16

Group 30 Electrical System—VNL, VNM
Typical Circuit Components
Wiring harnesses, wires & connectors
Each circuit uses a wire of a specific size, based on the
current demands for that circuit. The circuit number is
stamped into the insulation every 76 mm (3 in.). This aids
in proper connections and simplifies circuit tracing.
Insulation is cross-linked and flame resistant. White wires
are grounded circuits. Red wires are main power feeds.
Black wires are protected with a fuse or circuit breaker,
etc.
Some wires are grouped together and encased in a split
plastic casing or braided tubing called a loom. This group-
ing of wires is called a harness. Major wiring harnesses
are joined by using a multiple plug and receptacle con-
nector block.
Each harness or wire must be held securely in place by
clips or other holding devices to prevent chafing of the
insulation.
Terminals used throughout the system are Deutsch, Amp,
JAE, KOSTAL and Packard. All terminals are soldered
unless prohibited by the terminal manufacturer.
Circuit protection
To protect wiring and equipment from overloads, circuit
protectors such as fuses, circuit breakers or fusible links
are used.
WARNING
Failure to use proper circuit protection devices in the
vehicle can result in personal injury or damage to the
vehicle. Replace blown fuses only with fuses of the
same rating. Replace fusible links only with proper
replacement parts of the exact gauge and length.
Failure to use proper circuit protection could overload
the circuit, causing possible personal injury and severe
damage to the vehicle.
Fuses
The most common protector in the vehicle circuit is a
fuse. A fuse consists of a fine wire or strip of metal
inside a glass tube or plastic housing. The strip melts and
interrupts the flow of current in the circuit when there is
an overload caused by an unwanted short or ground. The
fuse is designed to melt before the wiring or electrical
components in a circuit can be damaged. Naturally, the
cause must be located or the new fuse will also blow.
Since different circuits handle different amounts of current,
fuses of various ratings are used. Fuses are rated in
amperes. Be sure to replace a blown fuse with a fuse
of the same rating.
A new feature for the VN Series vehicle is the maxi-fuse,
which is designed for a larger amount of current than a
regular fuse.
14
1) Good fuse
2) Blown fuse
Design and Function
W3000484