Chevrolet P 1989, Схемы проводки

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WIRING DIAGRAMS 5
WIRING DIAGRAMS 6
path. For example the switch controlling the headlights is
at the power end of the circuit while the door switch
controlling the domelight completes the ground path.
Relays are remotely controlled switches. They are used
in high current circuits and in circuits controlled by
sensors.
Relays are designed so that a small current circuit wi!3
he able to control a large current circuit.
CIRCUIT BREAKERS (Figure 7)
Circuit breakers are another form of circuit protector.
There are two types of circuit breakers; automatic reset
and remote reset.
The automatic reset breaker opens when excess
current heats a bimetallic strip, causing the strip to bend
and open a set of contacts. Then the strip cools and
closes the contacts. So the circuit breaker opens and
closes until the excess current condition is corrected or
the circuit is disconnected from the power supply.
The remote reset circuit breaker has a heating wire
wound around the bimetallic strip. When an excess
current happens, the strip heats, bends, and opens the
contacts. Then a small current flows through the heating
wire, keeping the strip hot and the contacts open. This
type of breaker will stay open until either the power supply
is disconnected from the circuit or the breaker is removed
from the circuit. Then the breaker can cool and reset.
CIRCUIT LOADS ( F i g u r e 7)
Circuit loads are the components that use most of the
energy in circuit. The energy converts to motion, light, or
heat, lights, motors, and engine heaters are the most
common loads in circuits.
CIRCUIT DIAGNOSIS
A clear understanding of the circuit and a wiring
diagram are needed for effective diagnosis. Use a logical
sequence of testing to find the trouble. Use the diagnostic
tools. After the trouble is fixed, make sure the circuit
works correctly.
CIRCUIT MALFUNCTIONS
There are three electrical conditions that can cause a
nonworking circuit; an "Open Circuit", a "Short Circuit",
or a "Grounded Circuit"
OPEN CIRCUIT (Figure 8)
An open circuit occurs whenever there is a break in the
circuit. The break can be corrosion at the connector, a
wire broken off in a device, or a wire that burned open
from too much current.
SHORT CIRCUIT (Figure 9}
A short circuit happens when the current bypasses part
of the normal circuit. This bypassing is usually caused by
wires touching, salt water in or on a device such as a
switch or a connector or solder melting and bridging
conductors in a device.
Figure 7—Circuit Controllers
FUSES (Figure 8)
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 and corrected before the fuse is
replaced 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 connecting rating.
CIRCUIT CONTROLLERS (Figure 7)
Circuit controllers consist of switches or relays.
Switches are usually operated by a mechanical means
such as a hand or lever. Switches are usually at the
beginning of a circuit but can be used to control a ground
Figure 5—Series/Parallel Circuits
FUSIBLE LINK
A fusible link is a section of wire that is usually four
gage sizes smaller than the circuit it protects. A special
insulation is used that swells when heated by the wire.
Fusible links are usually found in the engine compartment
harnesses. The function of the fusible link is to melt open
when an overload occurs, thus preventing any damage to
the circuit.
Figure 6--Circuit Components
Figure 4—Basic Circuits
SERIES CIRCUITS (Figure 4 and 5)
In a series circuit, the electrical devices are connected
together to form one current path to and from the power
supply. In a series circuit the same current flows through
all of the devices.
PARALLEL CIRCUITS (Figure 5)
In a parallel circuit, the electrical devices are connected
to form more than one current path to and from the power
supply. In a parallel circuit the supply voltage is the same
in each current path.
SERIES/PARALLEL CIRCUIT (Figure 5)
A series/parallel circuit consists of a single current path
circuit and a circuit with more than one current path to
and from" the voltage supply.
CIRCUIT COMPONENTS (Figure 6)
The usual circuit path starts at the power supply which
is the battery/generator system. Next in the circuits is the
circuit protection component which cars he a fusible link, a
fuse, or a circuit breaker. Then the circuit goes to the
circuit controller which can be a switch or a relay. From
the circuit controller the circuit goes into the circuit load.
The circuit load can be one light or many lights in parallel,
an electric motor or a solenoid. After the electricity has
passed through the load it must return to the power
supply via the ground path. The ground path can be a
wire in the harness or it could be through the load
housing into the body or frame, thus returning the
electricity to the power supply. The body and frame are
connected by flexible ground straps.