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Automobile Signal Light systems
installed on our early C1’s were very similar over the
C1 years, and also similar to the Full-Sized cars.
Recently, I had the opportunity to troubleshoot a
SoCal SACC member’s ’62 experiencing a total system
failure. No
signal lights working at all.
However, the parking and brake lights were
functional. The
initial inclination was a Flasher (elaborated on later)
failure which proved to be false.
With these symptoms I first realized
I needed to breakout the Signal Light circuitry from the
wiring diagram printed in ST-12 and develop some
troubleshooting techniques.
Basically, I needed to get smarter on the Signal
System. Since
tracking the Signal Light wires is difficult when
viewing the entire car wiring circuit, I extracted the
information to a different diagram.
This is the basis for this article, educate
myself and pass information on to others, who might be
interested. Since
I don’t know the readerships understanding of auto
electrical systems I will begin very basic.
Important Concept –
How to Turn a Light Bulb ON -
In order to
light an auto lamp (12 volt systems being discussed but
6V is the same) you
 need a
positive (+)12V source (wire from Battery) and a path
(wire) for returning to the
Battery
Negative (Ground) terminal.
The +12V is touched to the base “pin” on a lamp
and the return wire is touched to
the lamp metal housing and returned to the Negative Battery terminal.
This is a complete circuit and every electrical system
in your car uses this same situation to function (radio,
wipers, heater, etc).
The sources for +12V sources are in many
locations in the car but in order for any electrical
device to operate a return “ground” must get back to the
Negative Battery terminal.
As is very well known in Corvettes,
the car body is fabricated from fiberglass (a
non-conductive material) and wire ground straps are
strategically located to make a continuous ground path
back to the Battery.
This was the subject of a recent Larry Pearson
Tech Session.
Full-sized metal cars can rely on their metal bodies to
make this ground return to the Battery.
Automobile lamps contain a wire known as a filament, enclosed in
a vacuum, within a glass enclosure.
Some lamps have a single filament, or,
additional filaments can also be added.
Most auto lamps have single or double
filaments.
The adjacent diagram indicates a drawing
for an auto lamp.
The 2 lamp filaments pictured have a
common connection in the middle.
This connection usually is attached
internally to the lamp metal base.
On the bottom of the lamp base are 2
metal contacts which are connected to either
filament 1 or 2.
As is evident in the adjacent picture, a double filament will
have two contacts on the lamp base.
As labeled in the drawing, one filament
inside our C1 lamps is a parking light/tail light, and a second
filament is a signal/stop light.
One filament can operate while the other is
OFF, or they can both operate simultaneous.
The lamp base is inserted into a socket containing 2 matching
contacts and colored wires traveling into the car wiring system.
In the diagram used one wire is Violet,
one is Dk Blue and the middle one is Black
(ground).
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OK, That is it for
the simple Stuff!
Onto the C1 Signals.
A Flasher in the Signal Light system
is nothing more than a Switch which connects and
disconnects +12V to the auto lamps.
This
Switch is labeled “F” (Flasher) in the adjacent
diagram.
The Flasher plugs into most Fuse Blocks on our
cars. The
Fuse Block is a panel located on the inside of
the firewall, lower left drivers side.
The panel contains (depending on which
C1) several fuses which are installed to protect
specific devices in the car electrical system
(radio, heater, etc.).
It is the small round tin can shaped
device
and
is plugged
into the Fuse Block.
See adjacent picture.
As seen in the diagram, the Flasher is
connected to +12V when plugged into the Fuse
Block. A
wire (yellow in this case) then is inside the
car electrical harness which travels to the
Steering Column Signal Switch.
“Flasher Units are different”, i.e.,
they may not be interchangeable.
Original automotive designers design the
Flasher to be compatible with the type and
number of lamp bulbs they are required to flash.
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 As
the diagram on the left indicates, a Signal Light Switch
is the manual control which connects the Front, Rear,
Rt. & Lt. lamps. The Flasher Unit has 2 tabs on one end,
one of which is powered by a +12V.
A red wire from the ignition switch runs down to
the Fuse Block to supply the +12V power.
This means that the signals lights only work when
the ignition switch is turned ON.
Flasher Unit and Operation
The Flasher Unit, “F” as indicated
in the diagram, is basically a switch and
contains a bimetallic (two types of metal) strip
which when cold shorts (or connects) the two
tabs on the bottom of the Flasher Tin Can.
“When” the Flasher is connected to a lamp
and supplied with +12V, this will make a
complete circuit back to the battery.
The light is lit, and current (amperes)
flow through the Flasher and lamp.
When the lamp is glowing it is from the
filament heat inside the lamp and the same
amperes
traveling through the Flasher will
cause the bimetallic strip to heat and
“curl”, disconnecting the lamp.
The lamp goes out, the bimetal
strip cools (no amperes flowing) and
straightens out reconnecting the lamp
and the current flows again, until it
heats and disconnects.
Hence, a Flasher!
The IMPORTANT Fact to
remember with this discussion is, “THAT
THE AMPERES (CURRENT) FLOWING THROUGH
THE FLASHER CAUSES THE INTERRUPTION OF
“TURNING-ON AND TURNING-OFF” OF THE
FLASHER +12V.
When the Steering Col. Switch is
NOT connected to the lamps, there IS NO
current flowing through the Flasher and
The Flasher DOES NOT OPERATE.
ONLY, when the lamps are
connected will the flasher operate,
i.e., because the signal lamp is a
“LOAD” and connected to ground which
makes the Flasher operate.
The manual Signal Light Switch is
“switched” by the Signal Light arm on the left side of the steering
column. Pushing the arm up means
you turn Right, and vice versa.
Leaving the arm in the center position is a neutral position and the
signal are not suppose to be ON.
The two pictures below view the components underneath/behind the
steering wheel (Steering Wheel Removed).
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Done With The Basics – Now to the Meat of the C1
Signal Configuration.
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