1977 DATSUN PICK-UP ECU

Body
Electrical

System

RADIO

Noise

prevention

Position
vehicle
in
an

open
area

away
from
steel

buildings
run

engine
extend
antenna
to
its
maximum

length
set
volume

control

to
maximum
and
set
dial
at
a
medium

point
without

catching
broadcasting
wave

Condition

Ignition

system

Noise
occurs
when

engine
is

op

erated

Charging
system

Sound
of

alternating
current

pre

sents

When

accelerator

pedal
is

depressed

or

released
noise

presents

Supplement
equipment

When

engine
starts
noise

presents

Noise

still

presents
even
after

stop

ping
engine

Notes

a
Be
sure
to
locate

capacitor
as

close

as
to

noise
source
and
connect
in

parallel
Probable
cause
Corrective
action

High
tension
wire

Install
new

high
tension
wire

Ignition
coil
Install
a
0

51lF

capacitor
to

primary
side

terminal
of

ignition
coil

Note
Be

careful
not
to
install

capacitor
to

secondary
or

primary
breaker
side
other

wise

engine
becomes

improper

Install
bond

strap

Distributor
Secure
contact
of
carbon
electric

pole
and

rotor

Eliminate

sharp
tip
on

rotor

pole
or

cap
pole

by

scrubbing
with
a

screwdriver

Check

stagger
between
rotor

and
stator

Alternator
Install
a
0

51lF
capacitor
to

charging
termi

nalA

Note
Do

not

use
a
larger
capacitor

If

capacitor
is

installed
to
terminal
F

alternator
coil
will
be

damaged

Regulator
Install
a
0

51lF
capacitor
to
IGN
terminal

of

voltage
regulator

Operative
noise
of
water
tem

perature
and
fuel

gauges
Install
O

IIlF
capacitor
between
terminal
and

ground
wire

Note
If

a

capacitor
having
a

larger
capacity

is
used
indication
of

gauge
will
be
de

viated

b
Cut
lead
wire

as
short
as

possible

c

Ground
wire
should
be
attached
on

the

body

completely

d
Make
installation
and
connection
securely

e

Carefully
identify

or
OUT

mark
IN

BE
35

OUTLINE
OF
AIR
CONDITIONER

REFRIGERATION

SYSTEM

CONDENSER

COMPRESSOR

RECEIVER
DRYER

COOLING
UNIT

ELECTRICAL
CIRCUIT

OUTLINE
OF
AIR

CONDITIONER

The

air
conditioner
consists

es

sentially
of
a

cooling
unit

compressor

condenser
receiver

dryer
and

piping

The

cooling
unit

secured
with

three

brackets
is
a

ttached
to
the

location

occupied
by
the

package

tray

in
the
dash

panel

The

cooled
air
from
the
duct

is

directed
into
the

passenger
compart
Air

Conditioning

DESCRIPTION

CONTENTS

AC
2

AC3

AC
3

AC3

AC4

AC4

AC
5
DESCRIPTION

MAIN

RELAY

FAN
SWITCH

THERMO

SWITCH

PRESSURE
SWITCH

COMPRESSOR
RELAY

F
I
C
D

SOLENOID
VALVE
AC
5

AC
7

AC
7

AC
7

AC
7

AC
7

AC
7

ment

through
the
three

outlets
at

the

instrument

panel

The

compressor
serves
to

compress

the

vaporized
refrigerant
and
is
attach

ed

through
the
bracket
to
the
loca

tion

occupied
by
the

mechanical
fuel

pump
on
the

engine

The
condenser
cools
the

compres

sed

refrigerant
vapor
sent

by
the
com

pressor
and
is

located
on

the
front
of
the
radiator
in

the

engine
compart

ment

The
receiver

dryer

serving
as
a

reservoir

for

storage
of
the

liquid
sent

by
the
condenser
is

located
on
the

right
in
the

engine
compartment

The

piping
consists
of

two
flexible

hoses

and
five

copper
tubes
which

connect
various

components
of
the

air

conditioning
system

I

Cooling
unit

2

Expansion
valve

3
Receiver

dryer

4

Comressor
5

Condenser

6
Duct

@
Flexible
hose

@
Copper
tube

AC
2
AC724

Fig
AC
1

Cooling
system

Air

Conditioning

REMOVAL
AND
INSTALLATION

COMPRESSOR

REMOVAL

INSTALLATION

IDLER
PULLEY

FAN
BELT

TENSION
ADJUSTMENT

REMOVAL
AND
INSTALLATION

INSPECTION

COOLING
UNIT

REMOVAL
AND
INSTALLATION

DISASSEMBLY
AND
ASSEMBLY

INSPECTION

RECEIVER
DRYER
AND
PIPING

COMPRESSOR

REMOVAL

I
Remove

battery

2

Disconnect

compressor
lead
wire

at
connector

3
Loosen
idler

pulley
lock

nut
then

adjusting
bolt
Remove

compressor

drive
belt

from

compressor
pulley

AC477

Fig
AC
28

Removing
drive
belt

4

Discharge
system
Refer
to
Dis

charging
System
under
General
Service

section
CONTENTS

AC
25

AC25

AC26

AC
27

AC
27

AC27

AC
27

AC27

AC
27

AC
2B

AC
29

AC
29
REMOVAL

AND
INSTALLATION

INSPECTION

WIRING

HARNESS
AND

COMPONENTS

WIRING
DIAGRAM

MAINTENANCE

MAIN
RELAY

COMPRESSOR

RELAY

FAN
SWITCH

RESISTOR
FOR
FAN
SWITCH

THERMO
SWITCH

F
I

C
D
SOLENOID
VALVE
AC29

AC29

AC30

AC30

AC31

AC31

AC31

AC31

AC32

AC32

AC
32

5
Remove
flexible
hose

fixing
plate

and
disconnect
low
and

high
pressure

flexible
hoses
from

compressor

Notes

a
Use
two

wrenches
when
disconnect

ing
pipe

joints

b

Plug
flexible
hose
and

compressor

joint
openings
immediately
after

disconnection
to

prevent
entry
of

dust
moisture
laden
air
etc

Fig
AC
29

Disconnecting
ftexible

hoses

from
compressor

6
Remove

bolts

securing
fuel
tube

to

compressor
attachment

AC
25
Y
1

L

AC744

7
Remove
four
bolts

securing
com

pressor
to
its
bracket

Compressor
and

attachment

can
now
be
detached
as
an

assembly

Notes

a
There
are
a

total
of
four
bolts
two

on

upper
side
of
bracket
and
two

on
lower
side
of

compreSsor

Loosen

upper
bolts
and
remove

lower
bolts
When

removing
upper

bolts

securely
hold

compressor

with
one
hand

b
When

installing
temporarily
tighten

upper
bolts
then

tighten
lower

bolts

I

o

Fig
AC
37

Disconnectirt
connector
3

DISASSEMBLY
AND
ASSEMBLY

I
Remove
bracket
and
lead
wire

connector
main

relay
thermo
switch

resistor

motor
etc
from

cooling

unit

2

Remove
five
screws
and
duct

3
Remove
main

relay

4

Remove
thermo
switch

5

Remove
three
screws
and
five

springs
securing

upper
case
lower
case

and

rear
bracket

6
Unfasten

fittings
securing
inlet

and
outlet

pipes
Air

Conditioning

11
To
install

cooling
unit
reverse

the
order
of
removal

Notes

a

Apply
a
coat
of

fresh

compressor

oil
to

sealing
surfaces
when
COD

necting
pipe
joints

b
Use
two
wrenches
when
connecting

cooling
pipes

c
Evacuate
cooling

system
then
re

chaJge
with

refrigerant

Refer
fo

Evacuating
and

Charging

System
under
General
Service
see

tion

9

7

Upper
and
lower
cases
can
now

be

separated

8
Remove
motor
and
fan
as
an

assembly
Also
remove

evaporator

9
Peel
heat

insulating
tape
from

ex

pansion
valve
and
unfasten

clip
secur

ing
expansion
valve

capillary
tube
to

pipe

Remove

expansion
valve
from

evap

orator

10
To
install
reverse
the
order
of

removal

AG
28
d
Check

refrigerant
leakage
if
neces

sary
repair
Refer
to

Checking
for

Leaks
under
General
Service
sec

tion

Tightening
torque

Copper
tube

joint
nut

High

pressure
side
3

8
in

2
5
to
3
5

kg
m

18
to
25
ft
lb

Low

pressure
side
I

2
in

2
5
to
4
0

kg
m

18
to
29
ft
lb

00

L

1

Motor

2

Fan

3
Lower
case

4

Cooler
duct

5

Evaporator

6

Expansion
valve

7

Upper
case

8
Resistor

9
Main

relay

10
Thermo
switch

11
Cable
c

mp

12
Cable

3
Harness

AC725

Fig
A
C
38

Disassembling
cooling
unit

Expansion
valve

tightening

torque

5

kg
m
36
ft
Ib

Notes

a
When

installing
expansion
valve
on

evaporator
make
sure
that

temper

ature
oensing

capillary
tube
is
in
its

proper
position
on
outlet
side

b

Apply
a
coat
of
fresh

compressor

oil
to

sealing
surfaces
of

pipes

INSPECTION

Evaporator

Check

evaporator
for

leakage
or

damage
If

damaged
replace

Expansion
valve

Check

expansion
valve
for

leakage

or

clogging
If

clogged
clean
filter
in

expansion
valve
If

damaged

replace

RECEIVER
DRYER

AND

PIPING

REMOVAL
AND

INSTAUATION

Receiver
dryer

I
Disconnect

battery
ground
cable

2

Discharge
system
Refer
to

Dis

charging
System
under
General
Service

section

3

Disconnect

compressor
lead
wire

at

connector

4

Disconnect

cooling
pipes
at

joints

Acno

Fig
AC
39

Diaconnecting
coo

ing

pipes

Notes

a

Plug
all

piping

joints
immediately

after

pipe
disconnection
to

prevent

entry
of
dust
or
moisture
laden
air

into

receiver

dryer
or
air
aJOdi

tioning
system

b
Use

two
wrenches
when
dIsconnect

ing
cooling
pipes

5

Remove
four
screws

securing

receiver

dryer
bracket

to
vehicle

body

and
detach

compressor
relay
and

pres

sure
switch
as
an

assembly

6
To

install
receiver

dryer
and

piping
reverse
the
order
of
removal
Air

Conditioning

Notes

a

Apply
a
coat
of
fresh

compressor

oil
to

sealing
surfaces
when
con

necting
cooling

pipes

b
Use
two
wrenches
when

connecting

cooling
pipes

c

Evacuate

cooling
system
then
re

charge
with

refrigerant

Refer
to

Evacuating
and

Checking

System
under
General
Service

sec

tion

d
Check

refrigerant

leakage
if
neces

sary
repair

Refer
to

Evacuating
and

Charging

System
under

General
Service
See

tion

Condenser

Disconnect

battery

ground
cable

2

Discharge

system
Refer

to
Dis

charging
System
under
General

Service

section

3
Drain

engine
coolant

4

Remove
radiator

grille

5

Remove

radiator

shroud
and

radiator

On
automatic
transmission

models

disconnect
both

torque
converter
oil

hoses

Note

While

cooling
water
is
hot

take

precautions

against
scalding

6
Disconnect
two

pipes
from

con

denser
remove
two

screws

securing

condenser

Condenser

can
now
be

removed

AC485

Fig
AC

40

Removing
conden
er

Notes

a
Use

two
wrenches
when
disconnect

ing
pipe

joints

b

Plug
openings
immediately
after

disconnecting
pipes

7

To
install

reverse
the
order
of

removal

AC

29
Tightening
torque

Flare
nut
for

copper
tube

from

compressor

2
5
to
4
0

kg
m

i8
to
29
ft
Ib

Flare
nut

for

copper
tube

to
receiver

dryer

2
5

to
3
5

kg
m

i8
to
25
ft
lb

Notes

a
When

disconnecting
and

connecting

cooler

pipes
be
sure
to

use
two

wrenches

b

Apply
a
coat
of
fresh

compressor

oil
to

sealing
surfaces
when

con

necting
cooler

pipes

c

To

prevent

possibility
of

explosion

due
to

high

pressure
within

cooling

system
do

not
clean
condenser

with
steam

Always
use
cold
water

or

cold

compressed
air

d
Evacuate

cooling
system
then
re

charge
with

refrigerant

Refer
to

Evacuating
and

Charging

System
under
General

Service
sec

tion

e
Check

refrigerant
leakage
if
neces

sary
repair
Refer
to

Checking
for

Leaks
under
General
Service

sec

tion

INSPECTION

RecelYer

dryer

Check
for

refrigerant
leakage
or

damage

Check
for

proper
connection
of

two

lead
wires

running
to

pressure

switch

If

any
component

part
is
found

damaged
replace
receiver

dryer
and

pressure
switch
as

an

assembly

Condenser

I

Check

inlet
and
outlet

pipe
joints

and

sealing
surfaces
for

damage
Re

place
parts
if

damaged
or

leaky

2

Clogged
condenser
fins
or

air

pas

sages
may
reduce

cooling
efficiency
of

condenser
Clean
these

areas
with

dry

compressed
air

Piping

Check

piping
for

leakage
If

leakage

occurs
at
connections

retighten

connecting
nuts

Replace
if

leakage

persists

MAINTENANCE

Replace
any
wiring
harness
which
is

cracked
deteriorated
or

poorly
in

sulated

Always
replace
wire
with
those
of

the

same
diameter
Do

not
use
wire
of

smaller
diameter

Where

necessary
securely
retain

wire
harnesses
with

clips
or

tapes
so

that

they
will
not
be

frayed
or
worn

by
vibration

Notes

a

Repair
or

replace
any
electrical

part

which
is

questionable
or
likely
to

cause
a
short
circuit

When
disconnecting
battery
cables

always
disconnect

ground
cable
be

fore

positive
cable
Clean
battery

and
terminals
before

connecting

cables
then
connect

positive
cable

and

ground
cable
in

that
order

Apply
a
coat
of

grease
to
terminals

to

prevent
rust
formation

b
Do
not

attempt
to
conduct
a
con

tinuity
test
with
a

screwdriver
or

service
tools

always
use
test
lead

wires

c
Do
not

ground
terminals
when

circuits
are

open
or
unloaded

always
use

a
test

lamp
12V
3W

or
circuit
tester
as
a

load

MAIN
RELAY

Removal
and
Installation

The
main

relay
is
attached
to
the

cooling
unit

I

Disconnect

battery

ground
cable

2

Disconnect
main

relay
lead
wires

at
connector

3

Remove

cooling
unit

assembly

Refer
to
Removal
and
Installation

under

Cooling
Unit

4
Remove
the
screw

securing
main

relay
to

cooling
unit

and
detach
main

relay

5

To
install
main

relay
reverse
the

order

of
removal

Inspection

To

check

continuity
in

relay

circuit
use
a

test

lamp
or
an
ohm

meter

Continuity
between

points
3

and
4
should
exist
Air

Conditioning

When
a
12

volt
d
c
is

applied
across

points
3
and
4

continuity
between

points
I
and
2

should
also
exist

CD

00

COMPRESSOR
RELAY

Removal
and
installation

Disconnect

compressor
relay
lead

wires

at
connector

2
Remove

two
screws
securing
com

pressor
relay
to
receiver

dryer
and

detach

compressor
relay

3
To
install

compressor
relay
reo

verse
the
order
of
removal
@

I
ul

CDe
JOO

ID
IDe

@e

L

AC465

Fig
AC
42
Main

relay

Inspection

Using
a
test

lamp
or

an
ohmmeter

make

sure
that

compressor
relay
con

tacts

open
and

close
con

tinuously

Continuity
always
exists
between

points
3
and
4
When

current
flows

through

points
3

and
4

points
1

and
2
close
This

causes
current
to

flow

through
1
and
2

FAN
SWITCH

Removal
and
installation

1
Disconnect

battery
ground
cable

2
Remove

screws

securing
console

box
Withdraw
console
box
forward

and
disconnect
lead
wire
connector

3
Detach
switch
knob

4
From
rear
side
of
console
box

remove
screws

securing
switch
and

remove
switch

5
To
install
fan
switch
reverse
the

order
of
removal

AC
31
i
t
v

J

AC489

Fig
A

C
43
Compressor
relay

AC771

Fif
AC

44
Removing
fan
switch

Inspection

Check

continuiry
in
fan
switch

circuit
with
a
test
lamp
or

an
ohm

meter

I

011
I
2
3

ICD

Tt

tt

AC772

Fig
AC
45
Fan
switch

RESISTOR
FOR
FAN
SWITCH

Removal
and
Installation

I

Disconnect
battery

ground
cable

2
Remove

glove
box

3
Remove

cooling
unit
Refer
to

Removal
and
Installation
under

Cooling
Unit

4

Disconnect
resistor
lead
wires
at

connector

@

O
sn
I
3n

CD
00
@

AC492

Fig
AC

46
Resistor

for
fan
switch
Air

Conditioning

5

Remove
resistor

assembly
from

upper
side
of

cooling
unit

Resistor
is

inserted
into

case

6
To
install

res
istor
for
fan
switch

reverse
the

order
of
removaL

Inspection

Test

continuity
between
resistor

and
fuse

THERMO
SWITCH

Removal
and
installation

1
Disconnect

battery

ground
cable

2

Remove

glove
box

3
Remove

duct
from

cooling
unit

4

Disconnect
thermo
switch
control

cable
and
lead
wires

5

Remove
thermo
switch

Note

Capillary
lube
is
fitted
into

groove
in
cooler
unit

6
To

install
thermo
switch
reverse

the

order
of
removal

I

I

AC773

Fig
AC
47

Removing
thermo
switch

AC

32
Inspection

I

Fully
move
thermo
swirch
lever

to
COLD

2

Test

continuity
between

ter

minals
with
a
test

tamp
or

an
ohm

meter

Continuity
should
exist

3

Dip
capillary
tube
end

into
ice

water
Test
continuity
between
ter

minals

Continuity
should
not
exist

4

Replace
if
switch
is

found
dam

aged

F
I
C
D
SOLENOID
VALVE

Removal
and
installation

I

Disconnect
battery
ground
cable

2
Disconnect
lead
wires
and
vacu

um

tube

3

Remove
two
screws
securing
sole

noid

valve
and
remove
solenoid
valve

AC77
4

Fig
AC

48
Removing
F
l
C
D

solenoid
valve

4
To
install
solenoid
valve
reverse

the
order
of
removal

Inspection

1
Test

continuity
in
solenoid
valve

circuit
with

a
test

lamp
or
an
ohm

meter

2
Turn
both
fan
switch
and
thermo

switch
on

3
Run

engine
at
idle
and
check
to

be
sure
that
vacuum
is

present
in
line

between
solenoid
valve
and

diaphragm

Air

Conditioning

1foo

1t
1

t7
LV

I
1
Clutch
wheel

bearing

2

Snap
ring

3

Clutch
wheel

assembly

4

Magnet
coil

5

Shaft
seal

assembly

6

Service
valve

7

Flange
valve

O

ring

8

Cylinder
head

9

Cylinder
head

gasket

10

Cylinder
gasket

11
Valve

plate
assembly

12
Base

plate
gasket

13
Base

plate

14
O

ring

15
Oil
filler

plug

16
Clutch

assembly

17

Compressor
assembly

COMPRESSOR

CLUTCH

The
most

likely
source
of

problem

is
clutch

slippage
Factors
are
listed

here

Exercise

ample
care

I

Clearance
between
clutch

hub

and

pulley
should
be
0
4

to
0
6
mm

0
016
to

0
024
in

at
all

peripheral

points

2
Make
sure
that
there
is

no
oil
or

dirt

on
friction
surfaces
of
clutch

disc

clutch
hub
and

pulley
Remove

oil
or

dirt

with
clean
lint
free
cloth

3
Make
sure
that
terminal

voltage
at

magnetic
coil
is
above
IO
5V

REMOVAL

I

Using
Clutch

Spanner
Wrench

hold
clutch
hub
With
suitable

socket

wrench
remove
bolt

retaining
clutch

hub
to
crankshaft
H

@
@

AC776

Fig
AC
51

Remouing
bolt

2
Then

using
Clutch

Removing

Bolt
remove
clutch

assembly
from

cmnkshaft

Fig
AC
52

Removing
clutch

AC34
AC775

Fig
A
C
50

Exploded
view

of

compressor

3

Loosen
four

electromagnetic
coil

mounting
screws
Coil

assembly
can

then
be

taken
out

easily

Fig
A
C
53

Removing
magnetic
clutch

INSTALLATION

Locate
the

electromagnetic
coil

at

the

correct

position
on

compressor

housing
Then
secure
four

electro

magnetic
coil

mounting
screws

Tightening
torque

Electromagnetic
coil

mounting

screws

0
7

kg
m
5
1

ft
Ib