1997 BMW 328i o2 sensor wire
[x] Cancel search: o2 sensor wirePage 162 of 759
130-
1
6
FUEL
INJECTION
Throttie
position
sensor
(TPS),
Idie
speed
control
valve,
testing
and
replacing
testing
and
replacing
The
throttie
position
sensor
(TPS)
is
mounted
on
the
side
of
¡die
speed
is
maintained
by
the
ECM
via
the
¡die
speed
con-
the
throttie
housing
and
is
directly
connected
to
the
throttie
trol
valve
.
See
Fig
.
24
.
¡die
speed
is
adaptive
through
the
valve
shaft
.
The
ECM
sends
a
voltage
signal
to
the
potentiom-
ECM
and
no
¡die
speed
adjustments
can
be
made
.
Before
eter-type
sensor
and
monitors
the
voltage
that
comes
back
.
testing
the
valve,
confirm
that
the
throttie
position
sensor(TPS)
is
working
correctly
.
Check
TPS
function
by
disconnecting
the
harnessconnec-
tor
and
checking
reference
voltage
and
sensor
resistance
.
See
Table
e
and
Fig
.
23
.
If
voltage
is
not
present,
check
the
output
voltage
signal
from
the
ECM
and
check
the
wiring
be-
tween
the
sensor
and
the
ECM
.
If
the
sensor
resistance
is
in-
correct,
replace
the
throttie
position
sensor
.
NOTE
-
The
throttie
position
sensor
is
not
adjustable
.
If
test
re-
sults
are
íncorrect,
the
sensor
should
be
replaced
.
Table
e
.
Throttle
Position
Sensor
Tests
(DME
1
.7)
Testconditions
1
Terminais
1
Test
value
Harness
connec-
(
1
and
ground
in
15
VDC
(approx
.)
tor
disconnected,
harness
connector
ignition
on
0013235
Fig
.
23
.
Throttieposition
sensor
terminal
identification
on
M42
engine
.
Harnessconnec-
I
1
and
3
at
sensor
(
4k
ohms
(approx
.)
tor
disconnected,
terminais
ignition
off
Connector
dis-
1
and
2
at
sensor
Continuously
vari-
connected,
igni-
terminais
able
from
1-4
k
tion
off
.
Throttle
ohms
(approx
.)
with
rotated
from
¡die
out
interruption
to
fui]
position
BOSCH
DME
Ml
.
7
COMPONENT
TESTS
AND
REPAIRS
Fig
.
24
.
¡die
speed
control
valve
(arrow)
on
M42
engine
.
NOTE
-
"
The
tests
given
below
are
electrical
checks
only
.
They
do
not
check
the
mechanical
operation
of
the
valve
or
if
the
valve
is
sticking
or
worn
.
If
the
valve
is
suspect,
substituting
a
known
good
valve
is
the
best
way
to
check
for
amechanical
fault
.
1
.
Check
battery
(+)
voltage
to
valve
:
0013226
"
Disconnect
harness
connector
from
valve
.
"
Check
for
battery
voltage
at
terminal
2
(red/white
wire)
.
"
If
voltage
is
not
present
check
wiring
between
valve
and
main
relay
(terminal
87)
.
2
.
Check
that
ECM
signal
is
reaching
valve
:
"
With
engine
running,
check
that
¡die
speed
control
valve
is
audibly
buzzing
.
"
If
valve
is
not
working,
disconnect
wiring
harness
con-
nector
.
"
Connect
12V
probe
light
across
connector
terminais
.
"
Turn
ignition
key
on
;
probe
should
light
.
lf
probe
does
nof
light,
check
the
wiring
from
the
ECM
(pin
29)
to
the
valve
.
See
Table
h
.
lf
probe
does
light
but
¡die
quality
is
poor,
the
valve
is
most
likely
sticking
and
or
worn
and
should
be
replaced
.
Page 163 of 759
BOSCH
DME
MM
AND
M33
.1
COMPONENT
TESTS
AND
REPAIRS
Consult
Table
a
for
engine
application
information
for
the
Bosch
DME
3
.1
and
3
.3.1
systems
.
The
DME
3
.1
and
DME
3
.3
.1
systems
are
similar
in
opera-
tion,
with
knock
control
and
VANOS
operation
being
the
key
differences
.
DME
3
.1
engines
arenot
equipped
with
VANOS
or
knock
detectors,
while
the
DM
E3
.3
.1
system
is
.
CA
UTION-
Use
onty
a
digital
multimeter
when
testing
wiring
.
Use
of
an
analog
VOM
may
damage
the
engine
control
module
.
Fig
.
25
.
Mass
air
flow
sensor
.
Hot
wire
sensor
usedon
carswith
DME
Electrical
tests
of
the
main
and
fuel
pump
relays
and
the
3
.1
(1992
6-cylinder
models)
.
DME
engine
control
module
(ECM)
are
covered
earlier
in
this
section
.
Fuel
pump
tests
are
covered
in
160
Fuel
Tank
and
CAUTION-
Fuel
Pump
.
Use
only
a
digital
multimeter
when
checking
the
mass
air
flow
sensor
.
An
analog
meter
can
dam-
Mass
Air
Flow
Sensor
age
theair
flow
sensor
.
There
are
two
types
of
mass
air
flow
sensors
used
onthe
1
.
Disconnect
air
flow
sensor
from
air
cleaner
only
.
Leave
cars
covered
by
this
section
.
Testing
procedures
vary
de-
it
connected
to
duct
leading
to
intake
manifold
and
pending
on
type
installed
.
The
airflow
sensor
is
not
adjustable
leave
wiring
harness
connected
.
and
must
only
be
tested
with
a
digital
multimeter
.
Mass
Air
FlowSensor
Variants
"
1992
M50
engine
DME
M3
.1
.
.
.
.
...
..
mass
air
flow
sensor-hot
wire
"
1993-1995
M50
and
S50US
DMEM33
.1)
.
...
...
.
mass
air
flow
sensor-hot
film
Mass
air
flow
sensor
(hot
wire),
testing
and
replacing
When
the
engine
is
running,
a
current
is
used
to
heat
a
thin
wire
in
the
center
of
the
sensor
.
See
Fig
.
25
.
The
current
in
the
wire
is
regulated
to
maintain
a
temperature
of
100°C
more
than
the
air
passing
over
it
.
The
current
used
to
heat
the
wire
is
electronically
conneced
into
a
voltage
measurement
corre-
sponding
to
the
mass
of
intake
a¡
r
.
To
keep
the
wire
clean,
it
is
heated
to
a
temperature
of
about
1,000°C
(1,830°F)
for
one
second
.
This
"burn-off"
cycle
takes
place
automatically,
four
seconds
after
the
engine
is
tumed
off
.
lf
thehot
wire
breaks
or
if
there
is
no
output
from
the
air
flow
sensor,
the
ECM
automatically
switches
to
a
"limp-home"
mode
and
tucos
on
the
Check
Engine
light
.
The
engine
can
usually
be
started
and
driven
.
The
air
flow
sensor
has
no
inter-
nal
moving
parts
and
cannot
be
serviced
.
FUEL
INJECTION
130-
1
7
2
.
Start
engine
and
run
it
to
normal
operating
temperature
.
3
.
Rev
engine
toat
least
2,500
rpm,then
shut
it
off
.
Look
through
meter
at
hot
wire
.
After
approximately
four
sec-
onds
wire
should
glow
brightly
for
about
one
second
.
NOTE
-
If
the
wire
glowsas
specified,
then
the
airflow
meter
and
ECM
are
probably
operating
correctly
.
lf
the
wire
does
not
glow,
continue
testing
.
4
.
lf
the
wire
does
not
glow,
remove
air
flow
sensor
and
look
through
it
to
see
if
wire
is
broken
.
lf
wire
is
broken,
meter
will
have
to
be
replaced
.
5
.
Reinstall
air
flow
sensor
and
harness
connector
.
Peel
back
rubber
bootfrom
harness
connector
.
Working
from
rear
of
connector,
connect
digital
voltmeter
across
terminals
1
and
4
.
See
Fig
.
26
.
6
.
Start
and
rev
engine
toat
least
2,500
rpm,thenshut
it
off
.
After
about
4
seconds,
voltage
should
riseto
about
4
volts
for
about
one
second
.
lf
voltage
is
present,
but
wire
does
not
glow,
air
flow
sensor
is
faulty
and
should
be
replaced
.
7
.
lf
voltage
is
not
present
in
step
6,
turn
ignition
key
on
and
check
for
voltage
and
ground
at
sensor
.
There
should
beground
at
pin
4
.
There
should
be
positive
(+)
battery
voltage
at
pin
2
.
BOSCH
DME
M3
.1
AND
M32
.1
COMPONENT
TESTS
AND
REPAIRS
Page 164 of 759
130-18
FUEL
INJECTION
The
engine
coolant
temperature
(ECT)
sensor
sends
con-
tinuous
engine
coolant
temperature
information
to
the
ECM
.
Fig
.
26
.
Mass
air
flow
sensor
terminalidentifcation
on
carswith
DME
As
temperature
increases
sensor
resistance
decreases
.
M3
.1
fuel
injection
.
Mass
air
flow
sensor
(hot
film),
testing
and
replacing
MOTE-
A
burn-off
cycle
is
not
used
on
hot
film
sensors
.
8
.
With
ignition
off,
disconnect
harness
connector
from
air
ECT
Sensor
Location
flow
sensor
.
Using
a
digital
multimeter,
check
resis-
"
M50/S50US
engine
............
left
side
of
cylinder
tance
at
terminals
listed
.
head
under
intake
manifold
Air
Flow
Sensor
Test
Values
(DMEM3
.1)
"
Terminals
5
and
6
.
.
.
.........
..
.
..
....
3-4
ohms
If
any
faults
are
found,
check
wiring
lo
and
from
the
ECM
.
Make
ECM
pinout
test
as
listed
in
See
Table
i
.
Main
power
to
air
flow
sensor
comes
from
DME
main
relay
.
On
cars
with
DME
M3
.3
.1
a
hot
film
mass
air
flow
sensor
is
used
.
When
the
engine
is
running,
a
current
is
used
lo
heat
a
thinfilm
in
the
center
of
the
sensor
.
This
current
is
electroni-
cally
converted
into
a
voltage
measurement
corresponding
to
the
mass
of
intake
air
.
If
thehot
film
breaks
or
if
there
is
no
output
from
the
air
flow
sensor,
the
ECM
automatically
switches
to
a
"limp-home"
mode
and
tucos
on
the
Check
Engine
light
.
The
engine
can
usually
be
started
and
driven
.
The
air
flow
sensor
has
no
inter-
nal
moving
parts
and
cannot
be
senricedor
adjusted
.
CA
UTION-
Use
only
a
digital
multimeter
when
checking
the
mass
air
flow
sensor
.
An
analogmetercan
dam-
age
the
air
flow
sensor
.
BOSCH
DME
M3
.
1
AND
M32
.1
COMPONENT
TESTS
AND
REPAIRS
1
.
Disconnect
harnessconnector
from
air
flow
sensor
.
2
.
Turn
ignition
on
and
check
for
voltage
and
ground
at
connector
.
There
should
beground
at
pin
1
.
There
should
be
positive
(+)
battery
voltage
at
pin
3
.
If
any
faults
are
found,
check
wiring
to
and
from
ECM
.
Make
ECM
pinout
test
.
See
Table
j
.
NOTE-
Positive
(+)
battery
voltage
to
air
flow
sensor
comes
from
DME
main
relay
when
the
ignition
is
switch
on
orengine
running
.
Engine
coolant
temperature
(ECT)
sensor,
testing
and
replacing
0012704
Fig
.
27
.
Engine
coolant
temperature
(ECT)
sensor
(A)
is
located
be-
neath
top
engine
cover
(B)
and
crankcase
vent
hose
(C)
.
M52
engine
shown
.
M50
is
similar
.
1
.
Check
ECM
reference
voltage
to
sensor
:
"
Disconnect
harnessconnector
from
ECT
sensor
.
"
Turn
ignition
keyon
.
"
Check
for
5
volts
between
supply
voltage
wire
(brown/red)
wire
of
harness
connector
and
ground
.
"
Turn
ignition
key
off
.
"
If
voltage
is'
not
present
or
incorrect,
check
wiring
from
ECM
and
check
referencevoltage
output
at
ECM
(pin
78)
.
See
Table
i
(DM
E
3
.1)
or
Table
j
(DME
3
.3
.1)
2
.
Check
ECT
sensor
resistance
:
"
With
harnessconnector
disconnected,
check
resis-
tance
acrosssensor
terminals
.
"
Compare
tests
results
to
values
in
Table
f
.
Page 165 of 759
Table
f
.
Engine
Coolant
TemperatureSensor
or
Intake
Air
TemperatureSensor
Test
Values
(DME
3
.113
.3
.1)
Test
temperatures
Resistance
(k
ohms)
14±
2°F
(-10
±
1'C)
7-11
.6
68±
2°F
(20
±
1'C)
2
.1
-2
.9
17612°F
(80
t
V
C)
0
.27-0
.40
NOTE
The
test
values
listed
represent
only
three
test
points
from
a
continuous
resistance
NTC
sensor
.
Check
the
full
linear
response
to
increasing
temperatures
as
the
engine
warms
up
.
3
.
If
ECT
sensor
fails
these
tests,
it
is
faulty
and
should
be
replaced
.
If
no
faults
are
found,
reconnect
electrical
harness
.
WARNING
-
Do
not
replace
the
ECT
sensor
unless
the
engine
is
cold
.
Hot
coolant
can
scald
.
NOTE-
Use
"
a
new
copper
sealing
washer
when
installing
sensor
.
Replace
any
lost
coolant
.
Tightening
Torque
"
Engine
coolant
temperature
sensor
to
cylinder
head
.........
..
.
..
...
13
Nm
(10
ft-lb)
Intake
air
temperature
(IAT)
sensor,
testing
and
replacing
The
intake
air
temperature
(IAT)
sensor
signal
is
usedasa
correction
factor
for
fuel
injection
and
ignition
timing
.
Thissen-
sor
is
mounted
in
the
intake
manifold
behind
the
throttle
posi-
tion
switch
.
See
Fig
.
28
.
Check
TPS
function
by
disconnecting
theharnessconnec-
1
.
Check
that
ECM
reference
voltage
is
reaching
IAT
sen-
tor
and
testing
continuity
across
the
terminalswhile
changing
sor
:
the
throttle
position
.
Resistance
test
values
are
listed
below
.
If
"
Disconnect
IAT
sensor
harness
connector
.
the
resuits
are
incorrect,
replace
the
throttle
position
sensor
.
"
Turn
ignition
keyon
.
See
Fig
.
29
.
"
Check
for
5
volts
between
supply
voltage
wire
of
har-
ness
connector
and
ground
.
NOTE-
"
Turn
ignition
key
off
.
The
throttle
position
sensor
is
not
adjustable
.
If
test
re-
sults
are
incorrect,
the
sensor
should
be
replaced
.
IAT
Sensor
Supply
Voltage
"
M50/S50US
engines
.
........
grey
wire
and
ground
FUEL
INJECTION
130-19
Fig
.
28
.
Intake
air
temperature
sensor
location
on
M50/S50US
engine
(arrow)
.
If
voltage
is
not
present
or
incorrect,
check
wiring
from
ECM
and
check
reference
voltage
signal
at
ECM
(pin
77)
.
See
Ta-
ble
i
or
Table
j
.
2
.
Check
IAT
sensor
resistance
:
"
With
harness
connector
disconnected,
check
resis-
tance
acrosssensor
terminals
.
Compare
tests
resuits
to
values
in
Table
f
given
earlier
.
"
If
IAT
sensor
fafs
thistest
it
is
faulty
and
should
be
re-
placed
.
3
.
If
no
faults
are
found,
reconnect
electrical
harness
.
Throttle
position
sensor
(TPS),
testing
and
replacing
The
throttle
position
sensor
(TPS)
is
mounted
on
the
side
of
the
throttle
housing
and
is
directly
connected
to
the
throttle
valve
shaft
.
The
ECM
sends
a
voltage
signal
to
the
potentiom-
eter-type
sensor
and
monitors
the
voltage
that
comes
back
.
BOSCH
DME
M3
.
1
AND
M32
.1
COMPONENT
TESTS
AND
REPAIRS
Page 166 of 759
130-20
FUEL
INJECTION
Fig
.
29
.
Throttleposition
sensor
terminal
identification
on
M50
engine
.
Tableg
.
Throttle
Position
Sensor
Tests
(DME3
.113
.3
.1)
Test
conditions
I
Terminals
I
Testvalue
Harness
connector
13
andground
15
VDC
(approx
.)
disconnected,
igni-
in
harness
tion
on
connector
Harness
connector
1
and3
at
sen-
14
k
ohms
(approx
.)
disconnected,
igni-
sor
terminals
tion
off
Throttle
plate
rotat-
1
and
2
at
sen-
Variable
from
1
-
4ked
from
¡dieto
full
sor
terminals
ohms
(approx
.)
with-
throttle
position
out
interruption
¡die
Speed
Control
Valve
Coil
Resistance
Values
"
M50/S50US
engine
NOTE-
Terminals
1
and
2
..
.
................
20
t
5
ohms
On
cars
with
tractioncontrol,
do
not
confuse
the
throttle
Terminals
2
and
3
...................
20
t5
ohms
position
sensor
on
the
main
throttle
body
with
the
throt-
Terminals
1
and
3
..
.
..
:
............
.40
t
5
ohms
tle
positionswitch
on
the
secondary
throttle
body,
where
applicable
.
¡die
speed
control
valve,
testing
¡die
speed
is
maintained
by
the
ECM
through
the
¡die
speed
control
valve
.
The
¡die
controlfunction
compensates
for
engine
load
and
engine
operating
conditions
.
¡die
speed
is
adaptive
through
the
ECM
and
no
¡die
speed
adjustments
can
be
made
.
NOTE-
Before
testing
the
valve,
confirm
that
the
throttle
position
The
idle
speed
controlvalve
receives
positive
(+)
bat-
sensor
is
working
correctly
.
tery
voltage
from
the
main
relay
.
BOSCH
DME
M3
.
1
AND
M3
.3
.1
COMPONENT
TESTS
AND
REPAIRS
NOTE-
"
The
tests
given
below
are
electrical
checks
only
.
They
do
not
check
the
mechanical
operation
of
the
valve
.
If
the
valve
is
suspected
of
causing
poor
idie,
substitut-
ing
a
known
good
valve
is
the
best
way
to
check
for
a
mechanical
fault
.
1
.
With
engine
running,
check
that
¡die
speed
control
valve
is
buzzing
.
2
.
Turn
on
A/C
or
shift
car
finto
drive
.
¡die
should
remain
steady
orincrease
slightly
.
3
.
If
valve
is
not
buzzing,or
if
¡die
decreases
in
step
2,
stop
engine
and
disconnect
harness
connector
from
valve
.
Check
resistance
of
valve
across
its
terminals
.
See
Fig
.
30
.
Test
values
are
listed
below
.
NOTE
-
If
you
suspect
an
intermittent
fault,
lightly
tapthe
valve
while
testing
resistance
.
11250
Fig
.
30
.
¡die
speed
control
valve
terminal
identification
.
4
.
With
valve
harnessconnector
disconnected,
check
for
battery
voltage
at
red/white
wire
in
connector
with
igni-
tion
tumed
on
.
"
If
there
is
no
voltage,
check
wiring
between
connec-
tor
and
main
relayterminal
87
.
See
Electrical
Wiring
Diagrams
.
5
.
If
voltage
is
presentas
described
above,
check
wiring
between
ECM
and
valve
.
If
no
wiring
faults
are
found,
check
ECM
signal
to
valve
.
Page 176 of 759
130-
3
0
FUEL
INJECTION
Pin
Signal
Component/function
Signal
ECM
PIN
ASSIGNMENTS
Table
1.
ECM
Pin
Assignment-Bosch
DME
M3
.1
1
output
Fuel
pump
relay
control
Fuel
pump
relay
switches
with
engine
runningor
cranking
(crankshaft
position
Signal
mustbe
present
for
relay
switchover)
2
1
output
1
Idle
speed
control
valve
1
Pulsad
ground-
close
signal
(seealsopin29)
3
output
Fuel
injectorcontrol,
cyl
.
1
Pulsedground
(injection
pulsewidth
in
ms)
with
engine
running
4
output
Fuel
injectorcontrol,
cyl
.
3
Pulsedground
(injection
pulsewidth
in
ms)
with
engine
running
5
output
Fuel
injector
control,
cyl
.
2
Pulsedground
(injection
pulse
width
in
ms)
with
enginerunning
6
ground
Ground
Ground
for
fuel
injector
output
stages
7
vacant
-
-
8
output
Check
Engine
Check
éngine
lamp
control
ground
9
vacant
-
-
10
vacant
-
-
11
output
Throttle
valve
position
Load
signal
to
transmission
control
module
12
input
Throttle
position
sensor
Voltage
varies
with
throttle
position
13
output
Mass
air
flow
sensor
Air
flow
sensor
hotwire
burn
off
(voltage
for
0
.5
seconds
after
shutdown)
14
ground
Mass
air
flow
sensor
Ground
for
air
flow
sensor
15
vacant
-
-
16
input
Cylinder
identification
sensor
A/C
voltage
pulse
per
camshaft
revolution
(between
pin
16
and
44)
17
output
Fuel
consumption
(ti)
Fuel
consumption
output
(KVA
Signal)
to
instrument
cluster
18
vacant
-
-
19
vacant
-
-
20
vacant
-
-
21vacant
-
-
22
vacant
-
-
23
output
Ignition
control
(terminal
1),
cyl
.
no
.
2
Primary
Signal,
ignition
coil
cyl
.
no
.
2
24
output
Ignition
control
(terminal
1),
cyl
.
n
o
.
3
Primary
signal,
ignition
coil
cyl
.
no
.
3
25
output
Ignition
control
(terminal
1),
cyl
.
n
o
.
1
Primary
signal,
ignitioh
coil
cyl
.
no
.
1
26
input
Power
supply
(terminal
30)
Battery
voltage
(B+)
at
al¡
times
(terminal
30)
27
output
Main
relay
control
Main
relay
activation
(to
relay
terminal
85)
28
ground
Ground
Ground
for
ECM
and
sensor
shielding
29
output
Idle
speed
control
valve
Pulsed
ground-
open
signal
(see
also
pin
2)
30
vacant
-
-
31
output
Fuel
injector,cyl
.
no
.
5
Pulsedground
(injection
pulsewidth
in
ms),
cyl
.
no
.
5
32
output
Fuel
injector,cyl
.
no
.
6
Pulsedground
(injection
pulse
width
in
ms),
cyl
.
no
.
6
33
output
Fuel
injector,cyl
.
no
.
4
Pulsedground
(injection
pulsewidth
in
ms),
cyl
.
no
.
4
34
ground
Ground
Ground
for
output
stages
35
vacant
36
output
Evaporative
purgevalve
control
Pulsed
ground
with
engine
at
normal
temperature
and
varying
engine
load
37
output
Oxygen
sensor
heater
relay
control
Oxygen
sensor
heater
relayactivation
(ground
at
terminal
85)
38
vacant
-
-
39
vacant
-
-
40
vacant
-
41
input
Mass
air
flow
sensor
Voltage
(+)
42
vacant
-
-
43
ground
Ground
Ground
for
temperatura
sensors
(ECT
sensor,
IAT
sensor,
TP
sensor)
44
input
Cylinder
identification
sensor
A/C
voltagepulseper
camshaft
revolution
(between
pin
16
and
44)
Page 195 of 759
170
Radiator
and
Cooling
System
GENERAL
.
.
.....
.
...
.
.
.
.
.
....
.
.
.
.
.
.
.
.170-1
Coolant
Pump
and
Thermostat
........
.
.
.
.
170-1
Radiator
and
Expansion
Tank
.........
.
...
170-1
Cooling
Fans
.
....
.
.
.
.
.
.
.
.
.
.....
.
......
170-2
Warnings
and
Cautions
.
.
.
.
.
.
.
.
.
.
.
.
...
.
.
.
170-2
TROUBLESHOOTING
...
.
.
.
...
.
.
.
.
.
.
.
.
.170-2
Cooling
System
Pressure
Test
...
.
.
.
.
.
.
.
.
.
170-3
Thermostat
Quick
Check
.
.
.
.
...
.
.
.
.
.
.
.
.
.
170-3
Temperature
Gauge
Quick
Check
.
.
.
.
.
.
.
.
.
170-3
Cooling
fan,
testing
.
.
.
.
........
.
.
.
.
.
.
.
.
.
170-4
COOLING
SYSTEM
SERVICE
.
.
.
.
.
.
.
.
.
.
170-5
Coolant,draining
and
filling
.
.
......
.
.
.
.
.
..
170-5
Cooling
system,
bleeding
(radiator
with
integral
expansion
tank)
.....
170-6
GENERAL
This
section
covers
repair
and
troubleshooting
information
for
the
engine
cooling
system
.
For
heater
core
and
related
heating
and
air
conditioning
components,
see640
Heating
and
Air
Conditioning
.
Coolant
Pump
and
Thermostat
A
centrifuga¡-type
coolant
pump
is
mounted
to
the
front
of
the
engíne
.
The
belt-driven
pump
circulates
coolant
through
the
system
whenever
the
engíne
is
running
.
A
thermostat
con-
trols
the
flow
of
coolant
into
the
radiator
.
When
the
engíne
is
cold
the
thermostat
is
closed
so
coolant
bypasses
the
radiator,
recirculating
from
the
engíne
directly
back
to
the
pump
.
When
the
engíne
reaches
operating
tem-
perature,
the
thermostat
opens
and
coolant
circulates
through
the
whole
system
including
the
radiator
.
Radiator
and
Expansion
Tank
The
radiator
is
a
crossflow
design
.
A
translucent
expansion
tank
provides
for
coolant
expansion
at
higher
temperatures
and
easy
monitoringof
the
coolant
leve¡
.
On
4-cylinder
modeis,
the
radiator
expansion
tank
is
integral
with
the
radiator
.
See
Fig
.
1
.
RADIATOR
AND
COOLING
SYSTEM
170-1
Belt-driven
cooling
fan,
replacing
.
.......
.
.
.
170-7
Electric
cooling
fan,
replacing
.
.
.
.....
.
.
.
.
.
170-8
Auxiliary
cooling
fan,
replacing
.
.
.....
.
.
.
.
.
170-8
Thermostat,
replacing
.
.
.
.
.
.
.
.
.
.....
.
.
.
.
.
170-9
Coolant
pump,
replacing
..........
.
.
.
.
.
.
170-10
RADIATOR
SERVICE
.....
.
......
.
.
.
.
.
.
170-11
Radiator,
removing
and
installing
....
.
.
.
.
.
.
170-11
TABLES
a
.
Coolant
Temperature
Sensor
Wire
Colors
...
.
..
.
.
170-3b
.
Auxiliary
Cooling
Fan
Switching
Temperatures
.:.
.170-4
c
.
Auxiliary
Cooling
Fan
Temperature
Switch
Tests
..
..
.
...
...
.
.............
.
..
.
.
170-5d
.
Cooling
System
Capacities
..............
..
.
.
.
170-6
A
.
Expansion
tank
C
.
Dualtemperature
fan
switch
B
.
Radiator
drain
screw
Fig
.
1
.
Radiator
assembly
with
integral
expansion
tank
(4-cylinder
engine)
.
On
6-cylinder
models,
a
standalone
expansion
tank
is
used
.
On
cars
with
automatic
transmission,
ATF
is
circulated
through
an
additional
heat
exchanger
(ATF
cooler)
.
GENERAL
Page 197 of 759
Cooling
System
Pressure
Test
If
the
engine
overheats
and
no
other
cooling
system
testsindicate
trouble,
the
radiator
may
have
some
pluggedpassag-
A
cooling
system
pressure
test
is
used
to
check
for
internal
es
that
are
restricting
coolant
flow
.
leaks
.
Some
of
the
common
sources
ofinternal
leaks
are
a
faulty
cylinder
head
gasket,
a
cracked
cylinder
head,
or
a
Temperature
Gauge
Quick
Check
cracked
cylinder
block
.
The
coolant
temperature
sensor
is
located
on
the
intake
To
doa
cooling
system
pressure
test,
a
special
pressure
manifold
(left)
side
of
the
cylinder
head,
under
the
intake
man-
tester
is
needed
.
ifold
runners
.
See
Fig
.
2
.
WARNING
-
At
normal
operating
temperature
-
the
cooling
sys-
tem
is
pressurized
.
Allow
the
system
to
cool
before
opening
.
Release
the
cap
slowly
to
allow
sale
re-
tease
of
pressure
.
With
the
engine
cold,instan
a
pressure
tester
to
the
expan-
sion
tank
.
Pressurize
thesystem
to
the
specification
listed
be-
low
.
Pressure
should
not
drop
more
than
0
.1
bar
(1
.45
psi)
for
at
leakt
two
minutes
.
If
the
pressure
drops
rapidly
and
there
is
no
sign
of
an
externa¡
leak,
the
cylinder
head
gasket
may
be
faulty
.
Considera
compression
test
as
described
in
100
En-
gine-General
.
The
screw-on
type
expansion
tank
cap
should
also
be
test-
ed
using
a
pressure
tester
and
the
correct
adapter
.
Cooling
System
Test
Pressure
"
Radiator
test
pressure
.........
.
1
.5
bar
(21
.75
psi)
"
Radiator
cap
test
pressure
..
.
........
2
bar
(29
psi)
CA
UTION-
Exceeding
the
speclfied
test
pressure
could
dam-
age
the
radiatoror
other
system
components
.
Carefully
inspect
the
radiator
cap
for
damage
.
Replace
a
faulty
cap
or
a
damaged
cap
gasket
.
Thermostat
Quick
Check
In
later
models,
the
ECT
sensor
and
the
gauge
sender
are
combined
into
one
sender
unit
.
For
wire
colors
refer
to
Table
a
.
To
check
if
the
thermostat
is
opening
and
coolant
is
circulat-
ing
through
the
radiator,
allow
a
cold
engine
to
reach
operat-
ing
temperature
(temperature
gauge
needieapproximately
centered)
.
Shut
off
engine
.
Feel
the
top
radiator
hose
.
If
the
hose
is
hot
to
the
touch,
the
coolant
is
probably
circulating
cor-
rectly
.
If
there
are
any
cool
areas
in
the
hose
or
radiator,
cool-
ant
flow
to
the
radiator
is
probably
restricted
.
Check
for
a
faulty
thermostat
or
aplugged
radiator
.
NOTE-
A
thermostat
that
is
stuck
open
will
cause
the
engine
to
warmup
slowly
and
run
belownormal
temperature
at
highway
speed
.
A
thermostat
that
is
stuck
closed
will
re-
strict
coolant
flow
to
the
radiator
and
cause
overheating
.
RADIATOR
AND
COOLING
SYSTEM
170-
3
U
.¡ig
.v
Fig
.
2
.
Temperature
gauge
sender
on
M44
engine
.
Temperature
gauge
sender
location
is
similar
on
al]
engines
.
In
early
models,
the
engine
coolant
temperature
(ECT)
sen-
sor
for
the
fuel
injection
and
the
coolant
temperature
gauge
sender
are
located
side
by
side
.
Table
a
.
Coolant
Temperature
Sensor
Wire
Colors
Function
Sensor
Terminal
Wire
colors
location
number
Two
sensors
:
Temperature
Rear
1
Brown/violet
gauge
sender
2
Brown/yellow
ECT
sensor
Front
1
Brown/red
2
Brown
or
Brown/black
One
sensor
:
Temperature
Dual
1
Brown/yellow
gauge
sender
sensor
2
Brown/violet
ECT
sensor
3
Brown/red
4
Brown/black
or
Grey/black
TROUBLESHOOTING