GMC 1976 ZEO 6083 Maintenance Manual page 611

12- 6
CHASSIS ELECTRICAL
ing harness incorporates fusible links to protect the
wiring . Links are used rather than a fuse in wiring
circuits that are not normally fused . Each link is four
gauge sizes smaller than the cable it is designed to
protect and are marked on the insulation with wire
gauge size because the heavy insulation makes the
link appear a heavier gauge than it actually is .
Fusible Link Replacement (Figure 8)
A new fusible link can be installed, after the short
circuit is located and repaired, as follows:
1 . Disconnect battery ground cable.
2. Disconnect fusible link from junction block or
wiring harness.
3 . Cut harness directly behind connector to
remove damaged fusible link (figure 8) .
4. Strip harness wire approximately 1/2" .
5 . Position clip around new fusible link and har-
ness wire, crimp so that all wires are securely fas-
tened.
6. Solder connection using rosin core solder . Use
sufficient heat to obtain a good solder joint.
7 . Tape all exposed wires with plastic electrical
tape to prevent corrosion and shorting .
8. Connect fusible link to junction block.
9. Connect battery ground cable.
CIRCUIT DIAGNOSIS
Failures in a circuit are usually caused by short
or open circuits . Open circuits are usually caused by
Figure 8-Fusible Link Replacement
breaks in the wiring, faulty connections or mechani-
cal failure in a component such as a switch or circuit
breaker. Short circuits are usually caused by wires
from different components of the circuit contacting
one another or by a wire or component grounding to
the metal of the body due to a screw driven through
the wires, insulation cut through by a sharp metal
edge, etc.
The following information may aid in locating
and correcting a failure in the body wiring electrical
system .
If a major portion of the electrical circuit
becomes inoperative simultaneously, the failure may
be due to improper connections between the front
and rear harness, or between the front harness and
the chassis wiring connector on top of fuse block.
e If only one of the circuits is inoperative, the
failure is due to an open circuit or short in the af-
fected circuit. Short circuits usually result in blown
fuses or in the case of power equipment circuits, in
the circuit breaker opening the circuit. If the fuse is
not blown and the circuit affected is a lamp circuit,
check the bulb before proceeding with any checking
procedures .
Location
The fuse panel, Figure 9, is mounted on the bulk-
head panel behind the glove box assembly. To gain
access to the fuse panel, open the glove box and
unscrew the cover plate. Fuses and circuit breakers
located on this panel are illustrated in Figure 10 .
Protective circuit devices exterior to the fuse panel
are listed in the following chart:
Figure 9-Fuse Panel Location