MINIATURE LAMPS
MINIATURE LAMPS
• There are several types of miniature lamps
• You need to learn how to test and replace
them.
Bayonet style
- S.C. Bayonet The lamp on the
left is a Single
Contact (S C)That
means there is
one filament
inside the light
bulb. The index
pins are at the
same height. It
does not matter
what way you put
it into the light
socket assembly.
- D.C. IndexThe lamp on the
left is a Double
Contact (D C).
There are two
filaments and one
is brighter then
the other (tail
lights & Brake
Lights. Also the
index pins are at
different Heights
so it will go into
the light socket
assembly only one
way.
Bayonet style
Notice the index pins on the light
One is higher then the other
Bayonet style
Single Contact
Double Contact
Double Contact Amber
These all use the base of the lamp for Ground.
Wedge
These are very
common on side
markers and
brakes and tail
lights. Come in all
different sizes and
candle power.
Candle Power (cp)
is the Brightness of
the Lights or the
light intensity.
New Term is
candela.
One side is power the other side is ground.
Wedge
They also
come in
different
colors.
Wedge use a twist lock base
Plastic Wedge
The 3156
on the left
has one
filament
therefore it
has one
wire on the
each side
of the base.
The 3157
on the right
has two
filaments so
it has two
wires on the
base.
Clear & Amber
Some bulbs are clear
Some are amber for turn signals
Same is true on Plastic Wedge
Tail Light Lens
Clear Turn signal
Must
use a
amber
bulb
behind a
clear
lens
Amber Turn signal
May use a
clear bulb
behind a
amber lens
To test a Plastic Wedge bulb
Take Negative wire and clip it
to both wires on one side
Attach the Positive lead to the
front side of the bulb
Flip the bulb over and attach the
Positive lead to the other side
See how we have wires on
each side of the bulb (3157)
To test a Wedge bulb
Hook up the wires to both
sides of the bulb
And it will turn on
Courtesy lamps
Ridged Loop top
End Cap bottom
Festoon type
Instrument panel lights
Some times we need to replace dash lights how do we do that?
Many different types of bulbs
used in Instrument panels
194
Used in a twist lock socket
#74
#37
#74 & 37 are T1 3/4
#24
#24 are T2 3/4
#194
#194 are T3 1/4
#74 too small?..#194 too big? Could be a # 24
Some dash lights use LED’s
LED Lights come in several sizes
NeoWedge
Twist Lock BAX series
Pictures from
NeoWedge series
• Available in 3mm, 4mm, 5mm sizes
• To choose the correct bulb, measure the
diameter of the base
• Type A (T3) 3mm base is 8mm= 5/16“
• Type B (T4) 4mm base is 10mm= 3/8“
• Type C (T5) 5mm base is 12mm= 15/32“
• Info from
NeoWedge series
Remember when you test these light bulbs they are LED’s
you must have the right Polarity in other words, you have to
Hook up the power to the right side. A Diode is a one way
check valve. If you hook it up backwards it will not work.
Different colored Dash lights
MINIATURE LAMPS
Picture - Thanks to the
http://www.bulbman.com