permit easy identification of the various leads, a color
Q6-2. The primary purpose of a wiring diagram is
code in the insulation is widely used. You should
to perform which of the following functions?
consult the applicable support equipment manual or
1. It shows basic component relationship
handbook for the proper selection of wiring harness and
and component location using geometric
the proper color code for the vehicle that you are
shapes and symbols
maintaining. Examples of the automotive color codes
2. It shows, in detail, the electrical operation
are as follows:
of a particular circuit
3. It shows electrical wire routing between
RED LEAD. This color identifies wires that are
components and the approximate physical
connected to the battery (not fused), wires that are
location of the components
between the generator and the regulator, or wires that
4. It shows how each component is elec-
are between the ammeter and the circuit breaker/fuse.
trically connected to other components in
RED LEAD WITH YELLOW TRACER. These
the system and how they electrically affect
colors identify the primary ignition lead.
RED LEAD WITH BLACK TRACER. These
colors identify the wires between the ammeter and the
LEARNING OBJECTIVES: Identify basic
YELLOW LEAD. This color identifies the horn
electrical wiring diagrams and their symbols.
and light circuits (fused).
for electrical wires.
BROWN LEAD WITH BLACK TRACER.
These colors identify all ground connections except the
Ground support equipment has to meet certain
standards, but there are no set specifications or
standards for identifying the wiring used in the
BLACK LEAD. This color identifies the wires that
equipment. The older, less complicated equipment had
connect the taillights to the light switch.
few markings, no markings, or was poorly marked. In
BLACK LEAD WITH RED TRACER. These
the newer, more complex or special support equipment,
colors identify the headlight circuit for high or bright
the wiring is well marked.
Various methods of identification are used.
GREEN LEAD. This color identifies the headlight
Manufacturers are now using wiring identification
circuit for low or dim beams.
codes similar to those used in aircraft.
The alphanumeric code consists of a combination
Most automotive vehicle wiring is made up as a
of letters and numerals imprinted on each wire at
harness, with all leads coming out at the proper places
prescribed intervals along its entire run. Figures 6-4 and
and with the correct lengths to connect to the
6-5 and the accompanying discussion explain the codes
accessories. This simplifies the wiring of the
used in wiring installations. Complete details may be
automotive vehicle and serves to protect the wiring. To
GROUND, PHASE, OR THERMOCOUPLE LETTER
WIRE SIZE NUMBER
WIRE SEGMENT LETTER
Figure 6-5.--Alphanumeric wire identification code.