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ELECTRICAL SYSTEMS
SECTION 10-G
LIGHTING SYSTEM
CONTENTS OF SECTION 1O-G
LIGHTING SYSTEM
10-75
Paragraph
Subject
Page
Paragraph
Subject
Page
10-53
Lighting Switch and Circuit
10-56
Parking,
Signal, Tail,
Stop and
Breaker
.
.
.....
..
.. .....
. ..
10-75
License Lamps
.
.
.
.
.
.
.
.
.
.
.
.
.
10-80
10-54
Headlights and Controls
.
.
..
.
10-76
10-57
Interior Lights
a
nd Cigar
10-
55
Headlamp
Sealed
Beam Unit
Lighters
.
. ... .
.
..
. .
. .
.
.
..
.
.
10
-8 2
Replacement and Adjustment
10-78
SERVICE BULLETIN REFERENCE
Bulletin No
.
Page No
.
SUBJECT
10-53 LIGHTING SWITCH AND CIRCUIT
BREAKER
a. Description of Lighting Switch
The lighting switches used in 1948 models
and 1949
series
50-70 are similar in design, ex-
cept that the
1949
Series 50-70 switch incorpo-
rates
a
rheostat for controlling the brilliance
of the instrument panel
lights,
thus eliminating
the separate instrument panel light switch used
in 1948 models. Both switches have a thermo
circuit breaker for protecting the lighting cir-
cuits.
Both lighting switches are "push-pull" types
operated by a knob marked "LIGHTS". Three
positions of
the
switch knob provide control of
the lights as follows:
(1)
"Off"
posit ion
(knob all the way in)
cuts off all lights controlled by the switch.
(2) "Parking"
posit ion
(knob pulled out to
first notch)
turns
on the parking lights, tail
lights, and licen
se
light. The instrument lights
will also be turned on if
t
he controlling light
switc h
(1948)
or rheostat (1949) is turned
"
on" .
(3)
"
Driving"
position
(knob pulled out to
last notch) turns parking
lights off and turns
headlights on, while the other lights remain as
in the "Parking"
position.
The headlights will
be on the
"
upper" or "lower" beams depending
on the position of the separate dimmer switch.
On 1949
Series
50-70, the lighting switch
knob may be rotated to operate the rheostat
which controls the brilliance of the instrument
panel lights. Turning kn
ob counterclockwise
in-
cr eases brilliance of
lights;
turning knob
clock-
wise decreases brilliance and at limit of
clock-
wise travef the lights are turned off. Instrument
panel lights burn
only
when switch knob
is
in
"Parking" or
"
Driving"
position.
b. Description of Thermo Circuit Breaker
A thermo circuit breaker is incorporated in
the lighting switch assembly, to protect wi
ring
from damage du
e
to short circuits in any light-
ing circuit controlled by the switch, as w
ell
as
the stop lamps, map lamp and glove box lamp
circuits.
The thermo circuit
breaker
consists of a
bi-
metal blade and set of
contact
points
connected
in series with
the
lighting circuits. An abnor-
mal flow of current
through
the circuit breaker,
such as would be
caused by
a short circuit in a
lighting
circuit, heats
the bi-metal blade suffi-
ciently to separate the points and cause
them
to
vibrate. The
vibrating
blade
alternately
opens
and closes the circuit, thus reducing the flow of
current and
protecting
th
e
wiring
against
over-
heating
and
burning. The flickering light
pro-
duced
by
the
vibrating
circuit breaker
serves
as a warning to th
e
operat or of vehicle
that
a
short circuit
exists.
c. Test of Lighting Switch
If
the lighting sw
itch
is suspected of being
faulty, the contacts can be tested by connecting
a short jumper wire between
No.1
terminal and
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