Iat BMW 325i 1993 E36 Repair Manual
Page 168 of 759
130-
2
2
FUEL
INJECTION
Mass
air
flow
sensor,
replacing
1
.
Disconnect
harness
connector
and
intake
air
bootfrom
air
flow
sensor
.
See
Fig
.
32
.
Fig
.
32
.
To
detach
air
flow
sensor,
disconnect
harness
connector
(A)
;
3
.
Installation
is
reverse
of
removal
.
unclip
retainíng
clips
to
aír
filter
housing
(B)
;
andremove
large
hose
clamp
at
air
intake
bellows
(C)
.
M44
engine
with
traction
"
Use
a
new
copper
sealing
washer
when
installing
sen-
control
shown
.
sor
.
"
Replace
any
lost
coolant
.
2
.
Detachtwo
large
clipsat
air
filter
housing
and
work
air
flow
sensor
out
of
rubber
seal
in
filter
housing
.
Tightening
Torque
3
.
Installation
is
reverse
of
removal
.
"
Engine
coolant
temperature
"
For
ease
of
installation,
lubricate
large
rubber
seal
in
to
cylinder
head
.............
.
..
.
13
Nm
(10
ft-Ib)
air
filter
housing
with
silicone
lubricant
or
equivalent
.
"
No
adjustment
to
air
flow
sensor
is
possible
.
"
Carefully
check
that
all
hoses
and
seals
are
seated
Intake
air
temperature
(IAT)
sensor,
properly
.
replacing
Engine
coolant
temperature
(ECT)
sensor,
replacing
The
engine
coolant
temperature
(ECT)sensor
is
a
dual
temperature
sensor
.
One
circuít
provides
coolant
temperature
information
to
the
ECM
while
the
other
circuít
provides
coolant
temperature
information
to
the
instrument
cluster
.
WARNING
-
Do
not
replace
the
ECT
sensor
unless
the
engine
is
cold
.
Hot
coolant
can
scald
.
1
.
Disconnect
harness
connector
from
ECT
sensor
.
See
Fig
.
33
.
2
.
Unscrew
temperature
sensorfrom
cylinder
head
and
remove
BOSCH
DME
M5
.2
COMPONENT
REPLACEMENT
U1111
bis4a
Fig
.
33
.
M44
engine
coolant
temperature
(ECT)
sensor
located
above
oil
filter
(arrow)
.
The
intake
air
temperature
(IAT)
sensoron
cars
with
M44
engine
is
mounted
in
thetop
section
of
the
intake
air
filter
housing
.
See
Fig
.
34
.
1
.
Remove
electrical
harness
connector
from
IAT
sensor
.
2
.
Unclip
temperature
sensor
and
remove
from
air
filter
housing
.
3
.
Installation
is
reverse
of
removal
.
Throttle
position
sensor
(TPS),
replacing
The
throttle
position
sensor
is
located
on
the
side
of
the
throttle
housing
.
See
Fig
.
35
.
1
.
Unplug
harness
connector
from
sensor
.
Page 169 of 759
001ía4
i
Fig
.
34
.
Intake
air
temperature
(IAT)
sensor
in
top
section
of
air
filter
housing
.
¡die
speed
control
valve,
replacing
side
of
the
throttle
body
.
See
Fig
.
35
.
1
.
Disconnect
harness
connector
from
¡die
valve
.
0012725
Fig
.
35
.
M44
engine
:
Throttle
housing
showing
(A)
throttle
position
sensor
(fPS)
and
(B)
¡die
speed
control
valve
.
2
.
Remove
twomountingscrews
holding
sensor
to
throttle
housing
.
The
¡die
speed
valve
on
the
M44
engine
is
located
on
the
FUEL
INJECTION
130-23
2
.
Disconnect
vacuum
hose
and
retaining
screws
.
3
.
Pull
¡die
speed
control
valve
from
its
fittings
.
4
.
Installation
is
reverse
of
rémoval
.
Always
replace
0-
rings
and
seals
.
NOTE
Poor
driveability
may
be
notíced
after
installing
a
re-
placement
¡dio
control
valve
.
After
about10
minutes
of
driving,
the
idie
speed
should
retum
to
normal
.
SIEMENS
MS
41
.1
COMPONENT
REPLACEMENT
On-Board
Diagnostics
II
(OBD
II)
is
incorporated
into
the
Si-
emens
MS
41
.1
engine
management
systems
used
in
the
M52
and
S52US
engine
.
Refer
to
Fig
.
36
.
OBD
11
is
capable
of
detecting
a
fui¡
range
offaults
.
When
faults
are
detected,
a
Diagnostic
Trouble
Code
(DTC)
is
stored
in
the
system
ECM
.
The
Check
Engine
warning
light
will
also
come
on
if
an
emissions-related
fault
is
detected
.
The
most
efficient
way
to
diagnose
the
Siemens
OBD
II
system
is
by
using
a
specialized
scan
tool
.
The
OBD
II
system
is
capa-
ble
of
storing
hundreds
of
faults,
making
diagnostics
with
a
scan
tool
the
only
viable
method
.
Therefore,
system
diagnos-
tics
is
not
covered
here
.
NOTE
-
"
The
OBD
11
fault
memory
(including
an
illuminated
Check
Engine
light)
can
only
be
reset
using
the
spe-
cial
scan
tool
.
Removing
the
connector
from
the
ECM
or
disconnecting
the
battery
will
not
erase
the
fault
memory
.
"
The
16-pin
OBD
11
diagnostic
connector
is
located
on
the
lower
left
dash
panel
.
Refer
to
Fig
.
1
.
"
BMW
special
scan
tool
ora
"generic"
OBD
11scan
tool
must
be
used
to
access
DTCs
.
3
.
Installation
is
reverse
of
removal
.
No
adjustment
is
nec
essary
.
"
Table
1
lists
engine
control
module
(ECM)
pinouts
forthe
MS
41
.1
systems
.
SIEMENS
MS
41
.
1
COMPONENT
REPLACEMENT
Page 171 of 759
Mass
air
flow
sensor,
replacing
1
.
Disconnect
harness
connector
and
intake
air
boots
from
air
flow
sensor
.
See
Fig
.
37
.
Fig
.
37
.
Mass
air
flow
sensor
(arrow)
on
M52
engine
.
2
.
Installation
is
reverse
of
removal
.
"
No
adjustment
to
aír
flow
sensor
is
possible
.
"
Check
intake
hoses
for
cracks
and
vacuum
leaks
.
Engine
coolant
temperature(ECT)
sensor,
replacing
The
ECT
sensor
is
a
dual
temperature
sensor
.
One
circuit
provides
coolant
temperature
information
to
the
ECM
while
the
other
circuit
provides
coolant
temperature
information
to
the
instrument
cluster
.
1
.
Remove
left-side
top
engine
cover
.
4
.
Remove
sensor
.
5
.
Installation
is
reverse
of
removal
.
"
Replace
any
lost
coolant
.
0012703
"
Use
a
new
copper
sealing
washer
when
installing
new
Tightening
Torque
"
Engine
coolant
temperature
to
cylinder
head
.....
..
.
...
......
13
Nm
(10
ft-Ib)
FUEL
INJECTION
130-
25
0012704b
Fig
.
38
.
M52
engine
:
Engine
coolant
temperature
(ECT)
sensor
(A)
is
located
beneath
top
engine
cover
(8)
and
crankcase
vent
hose
(C)
.
Intake
air
temperature
(IAT)
sensor,
replacing
The
intake
air
temperature
(IAT)
sensor
for
the
M52/S52US
engine
is
mounted
on
the
bottom
of
the
intake
manifold
.
See
Fig
.
39
.
2
.
Unclip
crankcase
venting
hose
from
cylinder
head
cov-
er
.
See
Fig
.
38
.
Fig
.
39
.
M52/S52US
engine
:
Intake
air
temperaturesensor
location
in
bottom
of
intake
manifold(arrow)
.
Throttle
housing
shown
re
3
.
Under
intake
manifold,
disconnect
harness
connector
moved
.
fromsensor
.
1
.
Disconnect
intake
air
bootfrom
throttle
housing
.
Unbolt
throttle
housing
and
¡ay
aside
.
(It
is
not
necessary
to
disconnect
throttle
cable
or
electrical
harnessconnec-
tors
from
throttle
housing
.)
sensor
.
2
.
Remove
electrical
harness
connector
from
IAT
sensor
.
3
.
Unclip
temperature
sensor
and
remove
from
intake
manifold
.
4
.
Installation
is
reverse
of
removal
.
Use
a
new
gasket
at
the
throttle
housing
.
SIEMENS
MS
41
.1
COMPONENT
REPLACEMENT
Page 175 of 759
Tableh
.
ECM
Pin
Assignment--Bosch
DME
M1
.7
Pin
1
Signal
1
Component/function
1
Signal
45
Notused
46
Notused
47
Notused
48
Output
A/C
compressor
cut-out
Compressor
control
relay,
terminal
85
49
Notused
50
Notused
51
Output
Cyl
.
4
ignition
coil
control
Cyl
.
4
ignition
coil
52
Output
Cyl
.
2
ignition
coil
control
Cyl
.
2
ignition
coil
53
Not
used
54
Input
Battery
voltage
from
engine
control
module
Engine
control
module
relay,
terminal
87a
55
Ground
Ground,
ignition
Ground
point
56
Input
Ignition
switch,
terminal
15
Ignition
switch,
terminal
15
57
Notused
58
Not
used
59
Output
Throttleposition
sensor
and
volume
air
flow
sensor
Reference
voltage
(5
VDC)
60
Input
Programming
voltage
Data
link
connector
61
Notused
62
Notused
63
Notused
64
Input
Ignition
timing
intervention
Transmission
control
module
(EGS)
65
Input
Drive
range
P/N
Automatic
transmission
range
switch
66
Notused
67
Input
Crankshaft
position
RPM
sensor
Crankshaft
position
RPM
sensor
68
Input
Crankshaft
position
RPM
sensor
Crankshaft
position
RPM
sensor
69
Notused
70
Input
Oxygen
sensor
signal
Heated
oxygen
sensor
71
Ground
Oxygen
sensor
signal
ground
Heated
oxygen
sensor
72
Notused
73
Input
Vehicle
speed
signal
Instrument
cluster
74
Output
Engine
speed
signal
Instrument
cluster
75
Not
used
76
Input
Volume
air
flow
sensor
Volume
air
flow
sensor
77
Input
Intake
air
temperature
sensor
(IAT)
Intake
air
temperature
sensor
(IAT)
78
Input
Engine
coolant
temperature
Engine
coolant
temperature
sensor
79
Notused
80
Not
used
81
Input
Drive-away
protection
signal
(code)
On-boardcomputer
82
Not
used
83
Notused
84
Not
used
85
Input
A/C
pressure
Pressure
switch
86
Input
A/C
switch
Integrated
climate
regulation
control
module
87
Output
RxD
diagnosisdata
line
Data
link
connector
88
Output-Input
TxD
diagnosisdata
line
l
Data
link
connector
FUEL
INJECTION
130-
2
9
ECM
PIN
ASSIGNMENTS
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 177 of 759
Table
i
.
ECM
Pin
Assignment-Bosch
DME
M3
.1
Pin
Signal
Component/function
2
ignal
FUEL
INJECTION
130-
3
1
45
vacant
-
46
vacant
-
-
47
vacant
-
-
48
output
A/C
compressor
control
A/C
compressor
disabled
via
compressor
control
relay
49
vacant
-
-
50
output
Ignition
control
(terminal
1),cyl
.
n
o
.
4
Primary
signal,
ignition
coil
cyl
.
n
o
.
4
51
output
Ignition
control
(terminal
1),cyl
.
n
o
.
6
Primary
signal,
ignition
coil
cyl
.
no
.
6
52
output
Ignition
control
(terminal
1),cyl
.
n
o
.
5
Primary
signal,
ignitioncoil
cyl
.
no
.
5
53
vacant
-
54
input
Power
supply
Battery
voltage
(+)
from
main
relay
terminal
87
55
ground
Ground
Ground
for
ignition
control
56
input
Power
supply
(terminal
15)
Batteryvoltage
(+)
with
key
on
or
engine
running
57
vacant
-
-
58
vacant
-
-
59
output
Throttleposition
sensor
Throttleposition
sensorsupply
voltage
(5
VDC)
60
input
Data
link
connector
Programming
voltage
61
vacant
-
-
62
vacant
-
-
63
vacant
-
-
64
input
Ignition
timing
intervention
from
A/T
control
module
(only
active
during
gearshift)
65
input
Automatic
transmission
(A/T)
range
switch
Transmission
park
or
neutral
signal
66
vacant
-
-
67
input
Engine
speed/crankshaft
position
sensor
Crankshaft
position/rpm
(voltage
(VAC)
between
pins
67
and
68)
68
input
Engine
speed/crankshaft
position
sensor
Crankshaft
position/rpm
(voltage
(VAC)
between
pins
67
and
68)
69
vacant
-
-
70
input
Oxygen
sensor
Oxygen
sensor
signal
(0-1
VDC
fluctuating
with
engine
running)
71
ground
Oxygen
sensor
Oxygen
sensor
signal
ground
72
vacant
-
-
73
input
Road
speed
Road
speed
signal
from
instrument
cluster
74
output
Engine
speed
(TD)
Engine
speed
(TD)
signalto
instrument
cluster
75
vacant
-
-
76
vacant
-
-
77
input
Intakeair
temperature
(IAT)
sensor
Intake
air
temperature
(0-5
V,
temperaturedependent)
78
input
Engine
coolant
temperature
(ECT)
sensor
Engine
coolant
temperature
(0-5V,
temperature
dependent)
79
vacant
-
-
80
vacant
-
-
81
input
On-boardcomputer
Drive-away
protection
enable
82
vacant
-
-
83
vacant
-
-
84
vacant
-
-
85
input
A/C
pressure
switch
From
Integrated
climate
control
module
via
A/C
pressure
switch
86
input
A/C
compressor
on
From
Integrated
climate
control
module
87
input
Diagnostic
connector
(RxD)
Diagnostic
RxD
(receive)signal
to
pin
15
in
Data
link
connector
88
input/output
Diagnostic
connector
(TxD)
Diagnostic
TxD
(transmit)
signal
to
pin
20
in
Data
link
connector
ECM
PIN
ASSIGNMENTS
Page 182 of 759
130-
3
6
FUEL
INJECTION
Pin
1
Signal
1
Componentffunction
1
Signal
1
output
Ignition
coil
control,
cyl
.
2
Primary
signal,
ignition
coil
2
2
output
Ignition
coil
control,
cyl
.
4
Primary
signal,
ignitioncoil
4
3
output
Ignition
coil
control,
cyl
.
6
Primary
signal,
ignition
coil
6
4
ground
Ground
Ground
5
output
Fuel
injectorcontrol,
cyl
.
2
Pulsed
ground
(injection
pulse
width
in
ms)
cyl
.
2
6
output
Fuel
injectorcontrol,
cyl
.
1
Pulsed
ground
(injection
pulse
width
in
ms)
cyl
.
1
7
output
Mass
air
flow
meter
Mass
air
meter
signal
8
input
Mass
air
flow
meter
Mass
air
meter
signal
9
output
Instrument
cluster
Fuel
consumption
signal
10
output
Engine
coolant
temperature
(ECT)
sensor
ECT
signal
11
output
Fueltankpressure
sensor
Fueltankpressure
sensor
control
12
input
Throttleposition
sensor
(TPS)
Throttleposition
signal
13
-
14
input
Intake
air
temperature
(IAT)
sensor
Intake
air
temperature
signal
15
Traction
control
AST
module
16
input
Automatic
climate
control
Automatic
climate
control
17
18
input
Electronic
immobilizer
control
(EWS
II)
Electronic
immobilizer
control
(EWS
II)
module
19
Automatic
climate
control
Automatic
climate
control
20
-
Instrument
cluster
Instrument
cluster
21
output
Camshaft
actuator
(VANOS
solenoid)
control
Camshaft
actuator
(VANOS
solenoid),
switched
ground
22
output
Fuel
injectorcontrol,
cyl
.
3
Pulsed
ground
(injection
pulse
width
in
ms)
cyl
.
3
23
Fuel
injectorcontrol,
cyl
.
6
Pulsed
ground
(injection
pulse
width
in
ms)
cyl
.
6
24
Fuel
injectorcontrol,
cyl
.
4
Pulsed
ground
(injection
pulse
width
in
ms)
cyl
.
4
25
output
Oxygen
sensor
heater
control
Oxygen
sensor
heater
ground
26
input
Power
supply
(terminal
30)
Battery
voltage(B+)
at
all
times
27
output
Idle
speed
control
valve
Pulsed
ground-open
signal
(see
also
pin
53)
28
ground
Ground
Ground
29
output
Ignition
coil
control,
cyl
.
1
Primary
signal,
ignition
coíl
1
30
output
Ignition
coil
control,
cyl
.
3
Primary
signal,
ignition
coil
3
31
output
Ignition
coil
control,
cyl
.
5
Primary
signal,
ignition
coil
5
32
ground
Ground
Ground
33
output
Fuel
injector
control,
cyl
.
5
Pulsedground
(injection
pulsewidth
in
ms)
cyl
.
5
34
ground
Ground
Ground
35
output
Secondary
air
injection
Secondary
air
injection
pump
relay
control
36
output
Engine
speed
output
Engine
speed
signal
37
-
38
ground
Knock
sensor
Shielding
for
knock
sensors
39
output
Intake
air
temperature
sensor
(IAT
Sensor)
Voltagesupply
to
IAT
sensor
and
ECT
sensorEngine
coolant
temperature
(ECT)
sensor
40
output
Crankshaft
position
sensor
(Hall
effect)
Crankshaft
position
sensor
control
41
ground
Camshaft
position
(CMP)
sensor
Shielding
for
CMP
sensor
42
output
Throttle
position
sensor
(TPS)
TPS
ground
43
input
Camshaft
position/rpm
sensor
Camshaft
position/rpm
sensor
control
44
output
Throttle
position
sensor
(TPS)
Voltagesupply
to
TPS
(5
VDC)
45
Traction
control
AST
module
46
-
Instrument
cluster
Instrument
cluster
ECM
PIN
ASSIGNMENTS
Table
I.
ECM
Pin
Assignment-Siemens
DME
MS
41
.1
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 196 of 759
170-2
RADIATOR
AND
COOLING
SYSTEM
Cooling
Fans
TROUBLESHOOTING
Belt-driven
coolingfan
.
The
primary
cooling
fan
is
belt-
driven
.
It
is
mounted
to
the
frontof
the
coolant
pump
through
a
fan
clutch
.
The
fan
clutch
is
a
viscous
fluid
coupling
that
con-
trols
the
speed
of
thefan
based
on
engine
compartment
tem-
perature
.
Electric
cooling
fan
.
Models
with
M44
engine
and
stan-
dard
transmission
substitute
an
electric
fan
for
the
belt-driven
viscous
fan
.
This
is
attached
to
the
rear
of
the
radiator
and
controlledvia
the
DME
5
.2
engine
management
system
.
NOTE-
The
electric
cooling
fan
in
these
models
is
activated
by
the
engine
control
module
(ECM)
.
Auxiliary
coolingfan
.
In
al¡
models
a
two-speed
electric
auxiliary
cooling
fan
is
mounted
behind
the
front
grill
and
in
front
of
the
radiator
.
This
fan
is
primarily
used
for
the
A/C
sys-
tem,
but
also
operates
when
the
coolant
temperature
ex-
ceeds
a
predetermined
leve¡
.
Warnings
and
Cautions
The
following
warnings
and
Cautions
should
beobserved
when
working
on
the
cooling
system
.
WARNING
-
"
Atnormal
operating
temperature
the
cooling
sys-
tem
is
pressurized
.
Allow
the
system
to
cool
as
long
as
possible
before
opening-a
minimum
of
an
hour-then
release
the
cap
slowly
to
allow
sale
release
of
pressure
.
"
Releasing
the
cooling
system
pressure
lowers
the
coolants
boiling
point
and
the
coolant
may
boíl
suddenly
.
Use
heavy
gloves
and
wear
eye
and
laceprotection
to
guard
against
scalding
.
"
Use
extreme
care
when
draining
and
disposing
of
engine
coolant
.
Coolant
is
poisonous
and
lethal
to
humans
and
pets
.
Pets
are
attracted
to
coolant
because
of
its
sweet
smell
and
taste
.
Consult
a
veterinarian
immediately
if
coolant
is
ingested
byan
animal
.
CAUTION-
"
Avoidadding
cold
water
to
the
coolant
while
the
engine
is
hot
or
overheated
.
If
it
is
necessary
to
add
coolant
to
ahot
system,
do
so
only
with
the
engine
running
and
coolant
pump
tuming
.
"
Prior
to
disconnecting
the
battery,
read
the
bat-
tery
disconnection
cautions
given
at
the
front
of
this
manual
on
page
viii
.
TROUBLESHOOTING
Most
cooling
system
faults
can
be
grouped
into
one
of
three
categories
:
"
Cooling
system
leaks
"
Poor
coolant
circulation
"
Radiator
cooling
fan
faults
When
investigating
the
cause
of
overheating
or
coolant
loss,
begin
with
a
visual
inspection
.
Be
sure
to
check
the
con-
dition
and
tension
of
the
coolant
pump
drive
belt
.
Check
hoses
for
cracks
or
softness
.
Check
clamps
for
looseness
.
Check
the
coolant
leve¡
and
check
for
evidence
of
coolantleaks
from
the
engine
.
Check
that
the
radiator
fins
are
not
blocked
with
dirt
or
de-
bris
.
Clean
the
radiator
using
low-pressure
water
or
com-
pressed
air
.
Blow
outward,
fromthe
engine
side
out
.
Inspect
the
coolant
pump
by
first
removing
the
drive
belt
from
the
pump
.
Firmly
grasp
opposite
sídes
of
the
pulley
and
check
for
play
in
all
directions
.
Spin
the
pulley
and
check
that
the
shaft
runs
smoothly
.
NOTE-
The
coolant
provides
lubrication
for
the
pump
shaft,
soan
occasional
drop
of
coolant
leaking
from
the
pump
is
acceptable
.
If
coolant
drips
steadily
from
the
vent
hole,
the
pump
should
be
replaced
.
The
cooling
system
becomes
pressurized
at
normal
operat-
ing
temperature,
which
raises
the
boiling
point
of
the
coolant
.
Leaks
may
prevent
the
system
from
becoming
pressurized,
allowing
the
coolant
to
boil
at
a
lower
temperature
.
If
visual
ev-
idence
is
inconclusive,
a
cooling
system
pressure
test
can
help
to
pinpointhard-to-find
leaks
.
If
the
cooling
system
is
full
of
coolant
and
holds
pressure,
the
next
most
probable
cause
of
overheating
are
:
"
Faulty
radiator
fan
"
Loose
or
worn
drive
belt
"
Failed
thermostat
or
coolant
pump
"
Clogged/plugged
radiator
or
coolant
passages
.
NOTE
-
"
Some
early
style
coolant
pumps
were
fitted
wíth
fi-
berlplastic
type
impellers
.
Over
time,
this
impeller
can
wear
away
and
result
in
overheating
.
The
plastic
im-
peller
can
also
slip
or
free-wheel
on
the
pump
shaft
.
If
the
engine
overheats
and
no
other
faults
canbe
found,
theold
style
impeller
may
be
the
cause
of
the
problem
.
"
Only
pumps
with
the
updated
metal
impeller
should
be
used
for
replacement
.
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