TRUCK SERVICE MANUAL
FUSE AND CIRCUIT BREAKER PANELS
Most fuse panels provide space to install additional fuse
terminals if needed for installation of accessory circuits.
All chassis incorporate safety device to protect
electrical wiring and equipment from short circuits or
Locations of fuse panels on various vehicle models
are shown in this section.
fuses, circuit brakers or fusible links.
Circuit brakers are designed to open the circuit any
Fuses are designed to pass a given amount of
time current demand exceeds the capacity of the braker.
current. The current flow limit is indicated by the rating
In the event of short or overload, the circuit breaker will
of "Size" of the fuse (10 ampere, 14 ampere, etc.).
open due to excessive heat developed by the higher
Exceeding this limit will cause the fuse to "blow" opening
amperage passing through it. When the heat dissipates,
the breaker will close allowing current flow again.
After the cause of the overload is determined and
If the cause of the short or overload has not been
corrected, a new fuse must be installed in the circuit.
removed, the circuit breaker will open again to protect
Do not replace a "blown" fuse with a fuse of higher
the circuit. The current flow limit is indicated by the
capacity. To do so may result in damage to electrical
rating (capacity) of the circuit breaker15 amperes, 20
components or wiring.
Where fuse failure is
amperes, etc. Do not replace a circuit breaker with one
encountered, correct the cause of the overload and
of a higher capacity.
install a new fuse of the originally specified rating.
Fuses for most vehicle wiring circuits are grouped
generally grouped together in a circuit breaker panel.
together in a fuse panel (Fig. 1). Some fuse panels
Most circuit breaker panels provide space for installing
have removable fuse terminals which can be replaced if
Fig. 1 Fuze Panel (Typical)