Lesson 4/Learning Event 1
WIRING HARNESS IDENTIFICATION
Wires in an electrical system should be identified by a number, color, or code to facilitate tracing
circuits during assembly, troubleshooting, or rewiring operations. This identification should appear
on wiring schematics and diagrams and whenever practical on the individual wire. The assigned
identification for a continuous electrical connection should be retained on a schematic diagram until
the circuit characteristic is altered by a switching point or active component. An extension of this
system involves the use of suffix letters on wiring diagrams and wiring assemblies to identify the
segments of wires between terminals and connector contacts. The use of suffix letters is
advantageous when it is necessary to identify several individual wires of a common circuit that are
bound in the same harness.
Tank-automotive electrical circuits have been identified over the years with unique numbers for
specific circuits, based on the premise that maintenance personnel would become familiar with wire
numbers for these circuits and this familiarity would facilitate their ability to service a variety of
vehicles. Furthermore, common standard automotive electrical components in the supply system
such as headlight, taillight, and stoplight switch assemblies are marked with these standard wire
numbers. Therefore, these numbers should be used to the maximum extent practical for
identification of circuits in future military vehicle electrical systems. There are several practical
methods used to apply wire identification characters on wiring assemblies. Three commonly
employed methods are:
- Lettering may be hot stamped per MIL-M-81531, with 0.05-inch minimum height type,
directly on the wire or cable insulation using white letters on dark backgrounds or
black letters on light backgrounds.
- Lettering may be hot stamped per MIL-M-81531, with 0.05-inch minimum height type,
on MIL-I-23053/2 heat-shrinkable sleeving, length and diameter as required, assembled
over the wire insulation.
- Lettering may be indented or embossed with 0.093-inch minimum height type on band,
marker blank, MS39020, style and length as required, in accordance with MIL-STD-
130. Of these, the metal marker bands with indented or embossed characters are the
most durable and they remain legible even if painted over.
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