1984 NISSAN 300ZX Electrical System Workshop Manual

L6-13
L
T

AUTOMATIC SPEED CONTROL DEVICE (A. S. C. D.)
Wiring Diagram
L
.I .. I .-
i' I
:- .I
I I
- !
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SEL735D
EL-98

AUTOMATIC SPEED CONTROL DEVICE (A.S.C.D.)
-Preparation for Trouble-shooting Trouble-shooting
Remove AS C D control unit with harness AS C D control unit cznnot be set properly connected. I
Turn AS C D main switch "0FF"and then "ON"
to make sure indicator (located above combination
meter1 illuminates
Check for loose vacuum Check AS C D main
[-I switch and AS C D relay
Check power supply circuit for
A S C D control
unit SEL736D
Check stop switch. clutch
switch (MIT model).
inhibitor relay and
inhibitor switch (AIT model) POWER SUPPLY CIRCUIT CHECK
1 Release brake and clutch pedals
2 Turn ignition switch to "ON"
3 Turn A S.C.D main switch to "ON"
4. Check voltage between 0 and @ v Check harness between
AS C D power supply Check from harness side
-+ Release
A/T control -+ ..D" range
AS C D main wnch }-ON IOK Checksets:and
harness between control
unit and
set switch Voltmeter SELSlOD
SET SWITCH CIRCUIT CHECK
1. Turn ignition switch to "OFF". Go to "A S C D Actuator Check" -
2 Push A.S.C.D. set switch
3 Check continuity between 0 and @
Check from harness side
tion switch 4 OFF
C 0 ret switch + ON
SELBllD Ohmmeter
I
circuit
I Check set switch circuit for AS C D control unit 1
lNG Replace actuator !OK *
(Next page)
EL-99

AUTOMATIC SPEED CONTROL DEVICE (A.S.C. D.)
Trouble-shooting (Cont'd)
Turn ignition switch to "OFF"
Disconnect speedometer cable from trans-
mission
Connect an ohmmeter between
@ and
Slowly turn speedometer cable pinion by
hand to make
sure ohmmeter pointer
deflects
Ohmmeter pointer deflects twice per
rotation
of pinion.
0.
Check from harness side
Ohmmeter SEL7630
i
Check speed sensor circuit
(Digital type combination meter) -
(Refer to "METER AND GAUGES
- Needle Type Combination Meter"
~~~l~~~ AS c D
control unit
Check harness between A S C D
control unit and speed sensor
signal output terminal
of
combination meter
Does speedometer operate properly?
Go to "Speed Sensor Signal Check"
for checking combination meter
(Refer to "METER AND GAUGES
- Digital Type Combination Meter" )
Replace
speed sensor Check harness between AS C D
control unit and speed sensor
signal output terminal of
combination meter
EL-I 00

AUTOMATIC SPEED CONTROL DEVICE (A.S.C. D.)
Trouble-shooting (Cont'd)
Resume switch will not operate
Replace AS C D
control unit Check resume switch
h Accelerate switch will not owrate 11
Check accelerate switch circuit
v v Replace AS C D
control unit Check accelerate swttch
Engine hunts
Q
Check vacuum hose for breakage, cracks or
fracture
OK lNG Repair or replace hose
v
Does AS C D wire move smoothlv7
I NG v OK
Repair or replace wire
I
I Go to "Actuator Check" I
OK lNG Replace actuator
.I
Replace A S C D control unlt
RESUME SWITCH CIRCUIT CHECK
1 Turn ignition switch to "OFF"
2. Turn resume switch to "ON".
3. Check continuity between @ and 0
heck from harness side
on witch -+ OFF
M 0 h rn rn el e r SEL6120
ACCELERATE SWITCH CIRCUIT CHECK
1. Turn ignition switch to "OFF".
2. Turn accelerate switch to "ON"
3 Check continuity between @ and @
Check from harness %de
ignition switch + OFF
Accelerator witch -+ ON
SEL6130 Ohmmeter -
Large difference between set vehicle speed and
actual speed
I v
Check AS C D wire and actuator move
smoothlv
1 NG Replace wire 01
actuator
Check vacuum hose for breakage, cracks or
I fracture
4 NG
I OK Repair or replace hose
I Go to "Actuator Check" 1
4 NG
Replace actuator c OK Replace A.S C D
control unit
EL-I 01

AUTOMATIC SPEED CONTROL DEVICE (A.S.C.D.)
- Trouble-shooting (Cont'd)
AIT model only
0 When A S C D is set while vehicle is operating
in
"0 D " range, 0 D will be cancelled and
shifting to
0 D cannot be made thereafter
0 While vehicle is being driven using AS C D in
"0 D "range, 0 D will not be cancelled even
if actual car speed is 6 kmlh (4 MPH) lower
than
set speed (Set speed cannot be main-
tained
)
1 Check 0 D cancel circuit for AS C D control unit I
Replace A S C D 0 Electroniccontrolled A/T
control unit Check harness between
lock-up control unit and
AS C D control unit
Check harness between
0 D. cancel solenoid.
i) D. cancel switch and
AS C D control unit
0 Conventional Ail
I
ELECTRONIC-CONTROLLED A/T
EQUIPPED MODEL (E4N71B)
Turn ignition switch to "OFF".
Check continuity between @ and @
Check from harness slde . .~
ignmon switch - OFF
SEL737D Ohmmeter
CONVENTIONAL A/T EQUIPPED
MODEL (4N71B)
Turn ignition switch to "ON"
Turn 0 D. cancel switch to "OFF".
Check voltage @ -0 and 0-0
Check from harness side A '- b9ndt'~~n~~~~i~hO_N 0 Fihz L
Approx 12v ,I { .__. _- I .__.__.__.- -' Volmeter SEL741D
A.S.C.D. Actuator Check
1. Check continuity between terminal @ and
Continuity exist
... O.K.
terminals 0, @ and 0.
CAUTION:
Do
not attempt to remove valves from actuator.
2 Connect battery (approx 12V) to harness
connector
of actuator as shown below, and
apply vacuum to actuator
If diaphragm moves smoothly, actuator IS O.K.
CAUTION.
When checking actuator by applying vacuum, do
not apply engine vacuum directly
as it IS too strong
to check actuator properly.
LA s c D actuator B,m, 112VI
SEL739D
EL-I 02

SEL740D
CAUTION:
a Be careful not to twist wire when removing it.
Do not tense wire excessively during adjust-
ment.
Without depressing the accelerator pedal, adjust
wire tension with adjusting nut
Wire free play (at throttle lever):
0 - 0.5 mm (0 - 0.020 in)
a For A S.C.D. stop switch and clutch switch
adjustment, refer to
BR and CL sections.
a For vacuum pump and tank check, refer to HA
sect ion.
EL-1 038

LOCATION OF ELECTRICAL UNITS
EL-104