wiring list from which these wire numbers can be
found in Military Specifications, MIL-W-5088, which
cross-referenced to obtain information on the wiring.
may be found in your technical library.
This list contains valuable information that can be used
The first character in the alphanumeric code is a
in several different ways. For example, the wiring list
prefix (numeral), and is referred to as the unit number.
may contain the following:
The unit number is used only in those cases where more
Complete wire identification code or only the
than one unit is installed in an identical manner in the
same equipment. The wiring concerned with the first
wire numbers and segment letters
such unit bears the prefix 1, and corresponding wires
Wire gauge size of the wire
for the second unit have exactly the same designation,
except for the prefix 2. In the wire identification code
Length of the wire in inches
shown in figure 6-5, the 2 denotes that it is the second of
Component and terminal from which the wire
at least two identical systems in the equipment.
leaves
The letter following the prefix number identifies
Component and terminal to which the wire is
the circuit function. You are primarily concerned with
attached
function letters D, E, L, P, V, and X. The letter D denotes
instruments; E denotes engine instruments; L denotes
Figure 6-6 shows an example of wiring identifica-
lighting; P denotes dc power; V denotes dc power and
tion code use.
dc control for ac systems; and X denotes ac power.
These are identified in the wiring circuit function code.
WIRING HARNESS
The wire number that follows the circuit function
The wiring harness is a number of insulated wires
consists of one or more digits and differentiates
grouped together. They may be braid covered or
between wires in a circuit/circuits. A different number
secured in a nonmetallic tape. The wiring harness
is used for wires that do not have a common terminal or
should be securely mounted to prevent chafing,
connection, such as through a circuit breaker, switching
loosening of wire terminals, and breakage due to
device, or load.
vibration. The wires are color-coded or numbered and
Wires that are segmented by the use of connectors
cut to the proper lengths to make connections with
or terminals are given different segment letters.
various electrical components.
Normally, the segment letters are in alphabetical
sequence, beginning at the power source. The letters I
Wire Support and Protection
and O are not used because they could be mistaken for
the numerals 1 and 0. In the code shown in figure 6-5,
Wires in the electrical systems should be supported
the letter A signifies the first segment of wire 215. The
by cleats, clamps, or brackets at various points about
number following the segment letter identifies the size
the vehicle. When you are installing a new wire, be sure
of the wire or cable.
to keep it away from hot engine parts, which could
scorch or burn the insulation. Wires passing through
The ground, phase, or thermocouple letter fol-
holes in metal members of the frame or body should be
lowing the wire size number is used only when the
protected by rubber grommets or several turns of
segment of wire pertains to one of these items. You are
friction tape to prevent chafing or cutting on sharp
primarily concerned with the letters N, A, B, and C. The
edges.
letter N denotes a neutral wire; A, B, and C denote the
three separate phases of an ac power supply or source.
Ground Connections
The suffix letters at the end of the code are an
abbreviation of the material of which the wire is made.
Make certain the ground return connections made
ALUM indicates the wire is made of aluminum.
to the chassis frame or engine are clean and tight.
Where the engine or body is mounted on rubber or other
Another method of wire and cable identification
insulating material, use flexible bonding wires to
may use the complete wire identification coding or only
connect the parts together. Pay particular attention to
the wire number and segment letter on the wiring in the
these areas because rust or corrosion may form at these
equipment and on the diagrams for that equipment. If
connections, preventing the flow of current in the
this method is used, the operation and service
circuits even though the screws or bolts are tight.
instruction section of the technical manual contains a
6-6
