Datsun 1980 200SX Service Manual page 549

r
FUNCTION
AND
OPERATION
M ln swttch
The main switch
has
a
holding
type
of
circuit
When the
main
switch
is
turned ON
wilh lhe ignition
switch
ON
lhe
exciting
coil of the relay will be
ener
gized and the
relay
will
turn
ON lhus
supplying
current to
lhe
system
Although
the main switch automatical
ly
retums to its
original
position
the
current
is
sent
through lhe relay and
fed
to
the exciting coil
via
lhe main
switch in this
way
lhe
relay
will
remain
ON When the ignition
switch
is tumed off lhe relay will also
turn
off And
the relay will remain
in
operative
until lhe main switch is
turned ON
even
if the ignition switch
is
set to
ON
S t swttch
The
set
switch has
an
ON OFF
switch type
of
circuil
When the
set
switch
is depressed
lhe CRUISE
light
illuminates
Wilh
TROUBLE DIAGNOSES
TEST CONDITIONS
If
a
malfunction
is
found
be
sure
to
check lhe
following
before
perform
ing
the
system
tesl
I All wiring harness
connectors
must
be
securely
connected
ELECTRICAL SYSTEM
Auramatic
Speed
Control Device
A
S
C
D
lhe switch
depressed
lhe controller
cancels the preset car
speed
The controller will
preset
lhe
car
speed at
which lhe
car
is
running
when
the switch
is
released
Speed
s nsor
Contaln d In
speedom t
r
The
speed sensor
is
generating
two
pulses
per
revolution of the meter
cable
The output voltage
range and lhe
duty cycle must
be controlled prop
erly
S
ryo y
ly
TransdUc
r
The
servo
valve
causes
the
vacuum
valve and
atmospheric
valve
to
open
or
close
according
to
the input
current
and
adjusts
the
vacuum
from the
intake
manifold
Controll
r
The
c o nt r o l l e r
compares the
preset
speed with
the
actual
car
speed
and
maintains the
preset
speed
by
in
creasing
or
decreasing
the current
flowing through
the
servo
valve
2 A S
C
D
cable
must be
securely
installed with proper adjustment
3 Vacuum hoses must
be
properly
attached wilh
no
abnorrrial conditions
such
as vacuum
leakage sharp
bends
or
kinks
R I
y
ly
The release
v ve
is lhe
safety
valve
wliich
shuts off the
atmospheric
passage to lhe
vacuum
line
when
the
system
activates
Actu
tor
The
actuator
causes
ihe
throttle
to
open and close
by
vacuum through
lhe
servo
valve
Stop
wttch
The
stop
switch is used to release
lhe system
When the brake
pedal
is
depressed
this switch
cuts
off
lhe
power
supply
to
the
A S C D circuil
Stop
I
mp
switch
This switch
causes
the
stop
light
to
operate
At the
same
time
the oper
ating
signal
of the
stop light
circuit is
sent to
lhe controller
in
order
to
re
lease the
system
Inhibitor
r
lliy
The inhibitor relay releases
the
A s C D
system
when
the selector is
set to
N
or
P
position
DIAGNOSIS
WARNING
All
following
system
tests
can
be
performed
withoutrunning engine
Avoid making
test while
driving
car
or
running
engine
Indicator
light
will
not glow even
if ON button
of
main switch is depressed
with
ignition
switch ON
1
Burnt bulb
Faulty
main switch
L
Faulty A S C D
relay
EL 95