Service Information; Disconnecting Wires In Generator Circuit; Running Generator On Open Circuit; Correcting Generator Circuit Difficulties - Cadillac 1937 LaSalle VVI Information

149
E L E C T R I C A L
HORNS
T w i n air-tone horns, matched in tone, are used
on a l l series cars. T h e y are mounted by means
of a bracket and are cushioned in rubber. T h e
bracket is attached to the back of the air cleaner
on all 37 series V - 8 cars, between the radiator tie
rods on series 37-85 cars, and to the engine side
of the dash on series 37-90 cars. T h e horn button,
when depressed, permits a light current to pass
through a relay which is mounted on the horn
support bracket, and this in turn closes the circuit
for the heavier current that operates the horns.
GASOLINE GAUGE
The gasoline gauge is electrically operated.
The dash u n i t consists principally of two coils
spaced 90° apart w i t h an armature and pointer
assembly mounted at the intersection of the coil
axes. A n inertia dampener is provided on the
armature assembly to prevent vibration of the
pointer on rough roads.
The t a n k u n i t is essentially a rheostat, actuated
by a float in the tank. A cork washer, held by
a calibrated spring, prevents any slight float move-
ment from appearing on the dash unit indicator.
W h e n the tank is empty, the rheostat in the tank
u n i t is completely grounded. See F i g . 33. A l l cur-
rent through the dash unit then flows through
the coil at " e m p t y " side of indicator and the
pointer is pulled to the " e m p t y " mark. •
A s fuel is added, the float assembly rises. T h i s
moves the contact brush in the rheostat, intro-
ducing resistance into the circuit so that p a r t
of the current flows through the other coil and
the pointer is attracted away from " e m p t y " to a
position of balance between the two coils.
The gauge is compensated for temperature
variation and is not affected by variation in
battery voltage. It is connected in series w i t h the
ignition switch so that there is no discharge of
current when the ignition switch is turned off.
The ignition must be switched on to read the
gauge.
Service on the gauge can be obtained at U n i t e d
M o t o r s Service a n d A . C . Service Stations.
Service information is given in Notes 20 and 21.
INSTRUMENT PANEL
T h e instrument panel on series 37-50 and 60 is
an integral part of the body. T h e instrument
panel on series 37-65, 70, 75 is a single die cast-
ing w i t h mountings and arrangements as shown
in Plate 67, F i g . 30 and 31. T h e translucent dials
are lighted from behind by lamps having a rheo-
stat to control the light intensity. Series 37-85
cars have a similar instrument panel but have a
choke button which is located to the left of the
steering wheel.
The general arrangement and mounting of the
instruments on the instrument panel of series
37-90 car is different than the other series cars
and is shown in P l a t e 67, F i g . 32.
, Service Information
GENERATOR CIRCUIT
A l t h o u g h two distinct types of generator cir^
cuits are used, the following information applies
to all 37-series cars.
1. Disconnecting Wires in Generator Circuit
Whenever disconnecting any wires in the gen-
erator circuit, the starter circuit, or any wires
. in the harness opening at the regulator box, the
battery
must be disconnected first of all.
T h i s precaution is necessary to prevent any
possibility of the loose connections being grounded
in a way that will reverse the generator polarity
— a condition which m a y cause serious damage to
the charging circuit, as explained i n N o t e 5.
2. Running Generator on Open Circuit
N e v e r run or test the generator on open circuit.
If it should ever be necessary to operate the engine
without the battery connected, the generator
must be.grounded or both generator a n d regulator
will be damaged. T h i s can be done b y connecting
a " j u m p e r " wire between the G E N and the
G R O U N D terminals in the regulator.
3. Generator Circuit Difficulties
Charging circuit difficulties are of two types—
instances where the generator will not charge at
all, and instances of the charging rate being too
high or too low. If the generator will not charge,
check the following items in order:
1. Check the regulator unit to make certain
that the terminal marked G R D is properly con-
nected to a good ground. A l l connections in the
charging circuit must, of course, be clean and
tight, but this ground connection is of particular
importance. ..
v
2. If the car is radio-equipped, remove the
radio condenser from the generator. A n inter-
mittent short in the condenser m a y be the cause of
the difficulty, but in any e.vent it is advisable to
have the condenser disconnected when m a k i n g
tests.
3. Test to make certain that the generator
polarity is not reversed. If the polarity is reversed
it will be necessary to service the regulator u n i t
and to correct the generator polarity. See
N o t e '5.
4 G r o u n d the regulator terminal marked
" F " temporarily and gradually increase the engine
speed .to determine if the generator can produce
its rated output.* (See Specifications Page 163).
Note: D o not drive the generator at high speed
while making this check, or damage may
result, as there is no regulation whatever
with this hook-up.
*As measured on a precision ammeter.