1977 DATSUN PICK-UP battery

Body
Electrical

System

TROUBLE
DIAGNOSES
AND
CORRECTIONS

HORN

Condition

Horn

does
not

operate

Horn

sounds

continuously

Reduced
volume

and
or
tone

quality
Probable
cause

Discharged
battery

Measure
specific
gravity
of

electrolyte

Burnt

fuse

Faulty
horn
button

contact

Horn
sounds
when

horn

relay
terminal
s

is

grounded

Inoperative
horn

relay

Horn

sounds
when
B
and

H
horn

relay

tenninals
are
connected
with
a
test
lead

Damaged
horn
or
loose
horn

terminal
con

nection

Short
circuited
horn

button
and
or
horn

button

lead
wire

When
light
green
lead
wire
is

disconnected

from
horn

relay
terminal
s

horn

stops
to

sound

Inoperative
horn

relay

Loose
or

poor
connector
contact

Fuse
relay
horn
and
or
horn

button

Damaged
horn

BE
33
Corrective
action

Recharge
or

replace
battery

Correct
cause
and

replace
fuse

Repair
horn
button

Replace
horn

relay

Correct
horn
te
inal
onnection
or

replace

horn

Repair
horn
button
or
its

wiring

Replace
horn

relay

Repair

Replace

CD
m
Cl
@
D
@

I

j

1
To
instrument
harness
IS
To
battery
30
To
check
connector

2
To
full
transistor
amplifier
16
To
fusible
link
3t
To
headlamp
L
U
type
2

California
models
only
17
To
engine
harness
No
2
32
To
sido
marker
lamp
L
B

3
To
hood
switch
18
To
alternator
33
To
front
combination
lamp
L
H

4
To
engine
compartment
lamp
1
9
To
front
combination
lamp
R
n
34
To
horn
Low

ll
l
S
To
washer
motor
20
To
headlamp
R
H
type
2
3S
To
horn
High

l
l
0
6
To
auto
choke
heater
relay
1
To
side
marker
lamp
R
n
36
To
B
C
D
D
cut
olenoid
California
models

7
To
detector
dri
e
counter
22
To
headlamp
R
B
type
1
only

Non
Califunia
model
except
for
Canada
23
To
ground
37
To
block
tcrminal
distributor
California

8
To
ignition
relay
California
models
only
i4
To
thermal
transmitter
models
only

9
To
floor
sensor
relay
California
modeb
only
is
To
distributor
Non
California
models
only
38
To
ignition
coil
Non
California
models
only

n
10
To
inhibitor
relay
A
T
only
26
To
8
C
D
D
cut
solenoid
Non
California
39
To
condenser

t
II
To
head
lamp
relay
models
only
40
To
ignition
coil
and
resistor
@

12
To
horn
relay
27
To
fuel
cut
solenoid
California
models
only

OJ
v

m
13
To
voltage
regulator
28
To
auto
choke
heater

g
e
14
To
cooler
cable
29
To
headlamp
L
R
type
1

OJ
to

o
Q
m
r0

C
1
i

Ql
CIl
Il
l
3

m
ii
bl
l

l
l
if
3
i
m
1
Kickdown
solenoid
AlT

2
Oip

3
Inhibitor
switch
AfT

4
Oip

5
Engine

6
Battery
cable

7
Engine
slinger

8
Battery
cable
r
0
w
I

I

cf
n

L
J

TO
ENGtNE
ROOM
HARNESS
OJ

o
Q
m

O
Q
CIl
II

D
3

Body
Electrical

System

EMISSION
WARNING
SYSTEM

California

models

CONTENTS

FLOOR
TEMPERATURE
WARNING

SYSTEM

California
models

DESCRIPTION

FLOOR

TEMPERATURE

WARNING
SYSTEM

California
models

DESCRIPTION

The
floor

temperature
warning

system
consists
of

a
floor

temperature

sensing
switch
installed
on

the
vehicle

floor
a

floor

temperature
relay
a

floor

temperature

warning
lamp
and

harnesses

When
the

floor

temperature
rises

to

an

abnormal
level

the

warning

lamp

will

come
on

to
call
the
attention

of

the

driver

i

f
FUSIBLE
LINK

P

BATTERY
IGNITION

SWITCH
BE
43

8E
43
WARNING
LAMP

TROUBLE

SHOOTING
GUIDE
BE
43

BE
44

The

warning

lamp
also
comes
on

during
operation
of

the

starter
motor

permitting
inspection
of

the

lamp
s

condition
The

lamp
goes
out
after
the

engine
starts

Refer

to
Section
EC
for

details

WARNING
LAMP

Bulb

replacement

I

Remove
cluster
lid

2

Twist

warni
ng

lamp
socket

Socket

with
bulb
can
then
be

taken

out

3
Pick

up
bulb
from
socket

IGNITION
RELAY

I
I
4

Installation
is
in
the

reverse
se

quence
of

removaL

Bulb

wattage

Floor

temperature

warning

lamp

17W

Lamp
body
replacement

I
Remove

cluster
lld

2

Disconnect
lead
wire
at
connee

tor

3

Remove
two
screws

retaining

lamp
body

4
Installation
is

in
the

reverse
se

quence
of

removal

FLOOR

I
l

I
SENSOR

RELAY

WARNING
I

LAMP
FLOOR
SENSOR

ON

FLOOR

TEMPERATURE

LOW

OFF
FLOOR

TEMPERATURE

HIGH

7

BE697B

Fig
BE
64
Circuit

diagram
of
floor

temperature
warning

system

BE
43

The

refrigerant
within
the

thermo

bulb

changes
in

pressure
through
the

super
heat

condition
of

vaporized
re

frigerant
gas
which
comes
out
of
the

evaporator
causing
the

deflection
of

the

diaphragm
The
lift

of
the

ball

valve
attached
to
the

diaphragm
is

changed
by
the
deflection
of
the
dia

phragm
thus

controlling
the
amount

of

refrigerant
passing
the

orifice

ELECTRICAL
CIRCUIT

DESCRIPTION

The

electrical
circuit

of
the
air

conditioner
consists
of
four
switches

two

relays
a
solenoid
valve
a
fan

motor
and
a

compressor
magnetic

clutch
Air

Conditioning

Diaphragm

Orifice

Valve
ball

AC729
4

Sensing
bulb

Fig
A
C
6

Expansion
value

The

following
wiring
diagram

pro

vides
a

complete
description
of
the

whole
circuit

When
the

ignition
switch
and
the

fan
switch
are
ON
the
main

relay
is

activated

causing
battery
power
to

flow

through
the
fan
motor
and
the

magnetic
clutch
The

magnetic
clutch

is

activated

by
the
thermo
switch

AC
5
000

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

II
Cable

clamp

12

Cable

13
Harness

AC725

Fig
AC
7

Cooling
unit

pressure
switch
and

compressor
relay

The

blower
motor
fan

speed
is

con

trolled

by
the
fan
switch
and
resistor

The
solenoid
valve
is

also
activated

This
in
turn

causes
the

fast
idle
control

device
F
l

C
D
to
increase

engine

speed
when
the

vehicle
is

at
rest
with

the

engine
ON

MAIN
RELAY

The
main

relay
is
located
on
the

cooling
unit

When
the

ignition
switch
and
fan

switch

are
both
turned
on
the

COll

@

FAN
SWITCH

The

fan
switch

serving
as
a
control

unit
is

installed
on
the
center
console

This
switch

controls
the

blower
motor

speed
through
the
resistor
It
is
also

used
as
a

main

relay
switch

Fig
AC
I0
Fan
switch

THERMO

SWITCH

The
thermo

switch
is

located
on
the

upper
side
of
the

cooling
unit
and
is

controlled

by
the

cable
and
the
con

trollever
attached
to
the
console
box

It
is
so

designed
that
when
the
air

passing

through
the

evaporator
core
is

cooled
down

to
the

predetermined
Air

Conditioning

tacts
in
the

relay
are
closed
Then

electrical

power
from
the

battery
is

supplied
to
the
blower

motor
and
the

electrical
clutch
for
the

compressor

@

Dc

IDe

ID
1
1

l@

@
e

L
J

AC465

Fig
A
C
9
Main

relay

temperature
set

by
the

control
lever

it

automatically
turns

off
When
the

switch
is
turned
off
the

magnetic

clutch
is

turned
off

stopping
the
flow

of

refrigerant
inside
the

cooling
system

and

increasing
the

cooling
system
tem

perature

When
the

air
rises
to
the

pre

determined

temperature
the
thermo

switch

automatically
turns

on
In
this

way
the

temperature
of
the
air
dis

charged
from
the

cooling
unit
is
auto

matically
controlled
as
desired

PRESSURE

SWITCH

The

pressure
switch
is
turned
off

when

refrigerant
pressure
in
the

cooling
system
rises
to

an

abnormally

high
level
28

kg
cm2

398

psi
This

in

turn
turns
off
the

compressor

magnetic
clutch

actuating
the
com

pressor
relay
and

gradually
decreasing

pressure
in
the

cooling
system
When

the

pressure
drops
to
or
below
24

kg
cm2
341

psi
the

pressure
switch

again
turns
on

Thus

cooling

system
refrigerant

pressure
is

automatically
maintained
at

the

proper
value

a
t
all
times

AC
7
COMPRESSOR
RERAY

The

compressor
relay
is

attached
to

the
receiver

dryer
bracket
on
the

right

side

of
the

engine
compartment
This

relay
is

actuated
by
the

fan
switch

thermo
switch

and

pressure
switch
to

turn
on

and
off
the

compressor

magnetic
clutch

cv

1

2

AC731

Fig
A
C

11
Pressure
switch
and

compressor
relay

F
I
C
D
SOLENOID
VALVE

The
F
l
C
D
solenoid

valve
is
at

tached
to
the
dash

panel
in
the

engine

compartment
This
valve

supplies
vacu

um
to
the

F
I

C
D

diaphragm
through

the
vacuum
hose
connected

to
the

engine
intake
manifold
when
the

engine
is

at
idle
and

the

cooling
system

is
ON

thereby
raising
idle

speed
to
the

predetermined
rpm
800

IW

r

e

I

1
s

AC132

Fig
AC
12
F
l
C
D
solenoid

value

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

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