1995 BMW 318i Ecm

Table
j.
ECM
Pin
Assignment-Bosch
DME
M3
.3
.1

Pin



~
Signal



1
Componentffunction



1
signal

FUEL
INJECTION



130-
33

45



ground



Ignition
circuit
shield



Ground
shieldfor
ignition
circuit
monitoring

46



output



Fuel
consumption
(KVA
signal)



To
instrument
cluster

47



output



Crankshaft
rpm



Engine
speed
(TD)
signal
to
instrument
cluster

48



output



A/C
compressor
control



A/C
compressor
relay
terminal
85
49
vacant
-



-

50



output



Ignition
coil
control,
cyl
.
1



Primary
signal,
ignition
coil
1

51



output



Ignition
coil
control,
cyl
.
2



Primary
signal,
ignition
coil
2

52



output



Ignition
coil
control,
cyl
.
3



Primary
signal,
ignition
coil
3

53
vacant
-



-

54



input



Power
supply



Battery
voltagefrom
main
relay
(terminal
87a)

55



ground



Ground



Ground
for
ignition
control

56



input



Power
supply
(terminal15)



Batteryvoltage
with
key
on
or
engine
running

57



input



Ignition
timing
intervention



From
A/T
control
module
58
vacant
-



-

59



output



Throttleposition
sensor
(TPS)



Voltage
supply
to
TPS
(5
VDC)

60



input



Programming
voltage



Data
link
connector

61
vacant
-



-

62
vacant
-



-

63
vacant
-



-

64



input



A/C
on
signal



From
integrated
climate
control
module
65



input



A/C
pressure
signal



From
integrated
climate
control
module
via
A/C
pressure
switch

66



input



On-board
computer



Drive-away
protection
enable
(starter
immobilization
relay)

67
vacant
-



-

68
vacant
-



-

69



input



Knock
sensor
#2
(cyl
.
4,5,
6)



Knock
sensor
#2
signal

70



input



Knock
sensor
#1
(cyl
.
1,2,
3)



Knock
sensor
#1
signal

71



ground



Ground



Ground
for
knock
sensors
and
shields

72
vacant
-



-

73



input



Throttleposition
sensor
(TPS)



Throttleposition
signal

74
vacant
-

75
vacant
-



-

76
vacant
-

77



input



Intakeair
temperatura



Intakeair
temperatura
sensor
(0-5
VDC)

78



input



Engine
coolant
temperature



Engine
coolant
temperature
sensor
(0-5
VDC)

79
vacant
-

80
vacant
-



-

81



input



Automatic
transmission
gear
positionlneutral



A/T
parkor
neutral
position
signal
safetyswitch

82
vacant
-



-

83
vacant
-



-

84
vacant
-



-

85
vacant
-



-

86
vacant
-



-

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

130-
34



FUEL
INJECTION

Pin



i
Signal



1
Component/function



1
Signal

1



output



Oxygen
sensor
(monitoring
sensor)heater



Oxygen
sensor
heater
control
(switched
ground)

2



output



Idle
speed
control
valve



Pulsed
ground-close
signal
(see
also
pin
29)

3



output



Fuel
injector
control,
cyl
.
1



Pulsed
ground
(injection
pulsewidth
in
ms)
cyl
.
1

4



output



Fuel
injector
control,
cyl
.
4



Pulsed
ground
(injection
pulse
width
in
ms)
cyl
.
4

5



not
used



-



-

6



ground



Ground



Ground
for
fuel
injector
output
stage

7



not
used



-

8



1
output



1
Check
Engine



1
Instrument
cluster,
Check
Engine
lamp

9



not
used



-



-

10



input



Electronic
immobilizer
control
(EWS
II)



Electronic
immobilizer
control
(EWS
II)
module

11



output



Automatic
climate
control



Automatic
climate
control,
to
evaporator
controlier

12



not
used



-



-

13



not
used



-



-

14



not
used



-



-

15



not
used



-



-

16



input



Intake
air
temperature



Intake
air
temperature
Signal

17



input



Mass
air
flow
meter



Intake
air
signal

18



not
used



-



-

19



input



Oxygen
sensor
(monitoring
sensor)



Oxygen
sensor
control

20



output



Crankshaft/rpm
sensor



Crankshaft/rpm
sensor
control

21



input



Camshaft
position
sensor



Camshaft
position
signal

22



output



Ignition
coil
control,
cyl
.
3



Primary
signal,
ignitioncoil
3

23



output



Ignition
coil
control,
cyl
.
4



Primary
signal,
ignitioncoil
4

24



not
used



-



-

25



not
used



-



-

26



input



Power
supply
(terminal
30)



Battery
voltage
(B+)
at
al¡
times

27



input



Main
relay
control



Main
relay
activation
(terminal
85)

28



ground



Ground



Ground
for
ECM
and
sensor
shielding

29



output



Idle
speed
control
valve



Pulsed
ground-open
signal
(seealsopin
2)

30



output



Oxygen
sensor
(monitoring
sensor)
heater



Oxygen
sensor
heater
control
(switched
ground)

31



output



Fuel
injectorcontrol,
cyl
.
3



Pulsed
ground
(injection
pulsewidth
in
ms)
cyl
.
3

32



output



Fuel
injector
control,
cyl
.
2



Pulsed
ground
(injection
pulsewidth
in
ms)
cyl
.
2

33



I
not
used

40



input



Knock
sensor
#2
(cyl
.
3,4)



Knock
sensor
#2
signal

41



not
used



-



-

42



input



Vehicle
speed



Vehicle
speed
signal
from
instrument
cluster

43



not
used



-



-

44



output



Throttleposition
sensor
(TPS)



Throttleposition
reference
signal

ECM
PIN
ASSIGNMENTS

Table
k
.
ECM
Pin
Assignment-Bosch
DME
M5
.2

34



ground



Ground



Ground
for
ECM/
output
stages

35



not
used



-



-

36



input



A/C
compressor
relay



A/C
compressor
relay
control

37



not
used



-



-

38



not
used



-



-

39



not
used



-



-

Table
k
.
ECM
Pin
Assignment-Bosch
DME
M5
.2
(continued)

Pin



I
Signal



1
Componentltunction



1
Signal
45



I
output



I
Mass
air
flow
meter



I
Intake
airSignal

46



output



Oxygen
sensor
(monitoring
sensor)



Oxygen
sensor
control

47



not
used



-

48



not
used



-

49



output



Ignition
coil
control,
cyl
.
1



Primary
signal,
ignition
coil
1

50



output



Ignition
coil
control,
cyl
.
2



Primary
signal,
ignition
coil
2
51



not
used



-

52



not
used



-

53



input



Throttleposition
sensor



Throttleposition
Signal

54



input



Power
supply



Batteryvoltage
from
main
relay
(terminal
87)

55



ground



Ground



Ground
for
ECM

56



input



Power
supply
(terminal
15)



Battery
voltage
with
key
on
or
engine
running

57



output



Activate
cooling
fan
(man
.
trans
.)
control



Normal
speed
relay

58



not
used



-



-

59



not
used



-



-

60



input



Programming
voltage



Programming
voltage
via
data
link
connector,
pin
18

61



output



Evaporative
emissionvalve



Evaporative
emission
valve
control

62
vacant
-



-

63



output



Fuel
pump
relay



Fuel
pump
relay
control

64



not
used



-

65



not
used



-



-

66



not
used



-



-

67



not
used



-



-

68



input



Signal
above
80°C(man
.
tran
.)



Double
temperature
switch

69



input



Automatic
climate
control



Automatíc
climate
control

70



input



Knock
sensor
#1
(cyl
.
1,2)



Knock
sensor
#1
Signal

71



ground



Ground



Ground
for
analog
signals
and
knock
sensors

72



not
used



-



-

73



not
used



-



-

74



input



Engine
coolant
temperature
sensor



Engine
coolant
temperatura
Signal

75



not
used



-



-

76



not
used



-



-

77



output



Oxygen
sensor
(regulating
sensor)



Oxygen
sensor
control

78



input



Crankshaft/rpm
sensor



Crankshaft
position/rpmSignal

79



input



ABS
or
traction
control



ABS
or
AST
control

80



input



Engine
speed



Engine
speed
Signal
81



not
used



-



-

82



not
used



-



-

FUEL
INJECTION



130-
3
5

83



input



On-board
computar



From
On-boardcomputer
(terminal
4)

84



not
used



-



-

85



not
used



-



-

86



not
used



-



-

87



input



Diagnostic
connector
(RxD)



Diagnostic
RxD
(receive)signal
to
pin
15
in
Data
link
connector

88



output



I
Diagnostic
connector
(TxD)



Diagnostic
TxD
(transmit)
signal
to
pin
17in
Data
link
connector

ECM
PIN
ASSIGNMENTS

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

Table
I
.
ECM
Pin
Assignment-Siemens
DME
MS
41
.1
(continued)

Pin



I
Signal



I
Component/function



1
Signal

FUEL
INJECTION



130-
37

47
-

48



input



Crankshaft
position
sensor
(Hall
effect)



Crankshaft
position
sensor
control

49



input



Power
supply
(terminal
15)



Batteryvoltage
with
key
onor
engine
running
50



output



Solenoid
valve
(running
losses)



Running
losses

51



output



Carbon
canister
valve



Carbon
canister
valve
control

52vacant
-

53



output



Idle
speed
control
valve



Pulsed
ground-close
signal
(seealsopin29)
54



input



Power
supply



Battery
voltagefrom
main
relay
(terminal
87)

55
vacant
-

56
-

57



input



Knock
sensor
(cyl
.
1-3)



Knock
sensor
input
Signal

58



output



Knock
sensor
(cyl
.
1-3)



Knock
sensor
control

59



input



Knock
sensor
(cyl
.
4-6)



Knock
sensor
input
Signal

60



input/output



Diagnostic
connector
(TxD)



Diagnostic
TxD
(transmit)
signal
to
pin
18
in
Data
link
connector
61



output



Oxygen
sensor
heater
(monitoring
sensor)



Oxygen
sensor
heater
ground

62



output



Secondary
air
injection



Secondary
air
injection
control
valve

63



output



Knock
sensor
(cyl
.
4-6)



Knock
sensor
control

64



input



Camshaft
position/rpm
sensor



Camshaft
position/rpm
sensor
control

65



input



Camshaft
position/rpm
sensor



Camshaft
position/rpm
sensor
control

66
-

67



output



Oxygen
sensor



Oxygen
sensor
reference
voltage

68



output



Evaporative
purge
valve
control



Pulsed
ground
with
engine
at
normal
temperature
and
varyingengine
load

69



output



Fuel
pump
relay
control



Fuel
pump
relay
switches
with
engine
runningorcranking
(crankshaft
position
signal
must
be
present
for
relay
switchover)

70
vacant
-



-

71



output



Oxygen
sensor
heater
(regulating
sensor)



Oxygen
sensor
heater
ground

72



output



Oxygen
sensor
(monitoring
sensor)



Oxygen
sensor
referencevoltage

73



input



Main
relay
control



Main
relay
activation
(terminal
85)

74



output



A/C
compressor
control



A/C
compressor
relay
control

75



input



Oxygen
sensor



Oxygen
sensor
signal

76



not
used



-



-

77



input



Oxygen
sensor
(regulating
sensor)



Oxygen
sensor
signal

78



input



Oxygen
sensor
(monitoring
sensor)



Oxygen
sensor
signal

79



output



Oxygen
sensor
(regulating
sensor)



Oxygen
sensor
referencevoltage

80



Traction
control



AST
module

81



Traction
control



AST
module
82



Traction
control



AST
module
83



output



Crankshaft
position
sensor
(Hall
effect)



Crankshaft
position
sensor
control

84
vacant
-



-

85



output



Automatic
transmission



Automatic
transmission
control
module

86



input



Automatic
transmission



Automatic
transmissíon
control
module

87



input



Power
supply



Battery
voltage
from
main
relay
(terminal
87)

88



input/output



Diagnostic
connector
(TxD)



Diagnostic
TxD
(transmit)
signal
to
pin
17
in
Data
link
connector

ECM
PIN
ASSIGNMENTS

160-
6



FUEL
TANK
AND
FUEL
PUMP

Fig
.
7
.



Fuel
sender
and
pump
assembly
.

To
operate
the
fuel
pump
for
testing
purposes
without
hav-
Fuel
leve¡
sender
(left
side),



ing
to
runthe
engine,
the
fuel
pump
relay
can
be
bypassed
to

removing
and
installing



powerthe
pump
directly
.

The
procedure
for
removing
and
replacing
the
left
side
fuel



To
runthe
fuel
pump,
remove
the
relay
and
connect
the
leve¡
sender
is
similar
tothat
used
for
the
right
side
.
There
is



socket
for
relayterminal
30
to
the
socket
for
relay
terminal
no
.
no
fuel
pump
on
the
left
side
.



87
with
afused
jumper
wire
.
Relay
terminal
identification
is
shown
in
Fig
.
9
.
After
completing
the
tests,
remove
the
jumper

wire
.

FUEL
PUMP

The
electric
fuel
pump
ís
mounted
in
the
fuel
tank
in
tandem
with
the
right
side
fuelleve¡
sender
.
The
fuel
pump
delivers
fuel
at
high
pressure
to
the
fuel
injection
system
.
A
pressure
regulator
maintains
system
pressure
.
The
quantity
of
fuel
sup-
plied
exceeds
demand,
so
excess
fuel
retums
to
the
fuel
tank
via
a
retum
líne
.
See
130
Fuel
Injection
for
more
information
on
system
pressure
and
the
fuel
pressure
regulator
.

NOTE
-

Fuel
pump
removalprocedures
are
given
earlier
under
Fuel
leve¡
sender
(right
side)
and
fuel
pump,
remov-
íng
and
installing
.

Fuel
Pump
Fuse
and
Relay

The
fuel
pump
is
operated
by
a
fuel
pump
relay
located
ín
the
power
distribution
box
.
The
fuel
pump
circuit
is
protected
by
fuse
no
.
18
located
in
the
power
distribution
box
.
See
Fig
8
.

FUEL
PUMP

0013142

Fuel



DM
E
PUMP
main
re
ay



rel
ay

0

aoo
o
~a

aao
ó

Fig
.
8
.



Fuel
pump
relay
location
in
power
distribution
box
.

The
DME
engine
control
module
(ECM)
and
the
DME
main

relay
supply
power
to
the
coi¡
sideof
the
fuel
pump
relay
.
Dur-

ing
starting,
the
fuel
pump
runs
as
long
as
the
ignition
switch
is
in
the
start
position
and
continues
to
run
oncethe
engine

starts
.
If
an
electrical
system
fault
interrupts
power
to
the
fuel
pump,
the
engine
will
notrun
.

Operating
fuel
pump
for
tests

CA
UTION-

Relay
locations
may
vary
.
Use
care
when
identify-
ing
relays
and
when
troubleshooting
the
electrical
system
at
the
fuselrelay
panel
.
The
fuel
pump
re-
¡ay
is
a
four
pin
relay
and
has
a
1.5
mm
2
red
wireat
terminal
30
in
the
relay
socket,
lf
in
doubt,
con-
sult
an
authorized
BMW
dealer
.

NOTE-

Thejumper
wire
shouldbe
1.5
mm2
(14
ga
.)
and
in-
clude
en
in-fine
fuse
holder
with
a16
amp
fuse
.
To
avoid
fuselrelay
panel
damage
fromrepeated
connect-
íng
and
disconnecting,
also
include
a
toggleswitch
.
A
heavy-duty
jumper,
BMW
tool
no
.
613
050,
fs
also
available
from
en
authorized
BMW
dealer
.

0013034,

If
the
pump
does
notrun
with
the
jumper
installed,
the
fault
could
be
in
the
fuel
pump
or
the
wiring
to
the
pump
.
Check
the
pump
and
its
wiring
as
described
below
.

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
.

170-
4



RADIATOR
AND
COOLING
SYSTEM
A
quick
testat
the
coolant
temperature
gauge
sender
can



The
auxiliary
cooling
fan
comes
on
when
coolant
tempera

determine
if
the
gauge
is
functioning
correctly
.



ture
exceeds
a
predetermined
leve¡
or
whenever
the
air
condi-

tioning
is
on
.
A
dual-range
temperature
switch
for
cooling
fan
lf
the
gauge
needie
remains
at
the
rest
position
with
theen-



control
is
mounted
on
the
right
side
of
the
radiator
.
See
Fig
.
3
.
gine
warm,
remove
the
harness
connector
from
the
sender
and
jumper
the
correct
terminals
in
the
connector
to
simulate
a
high
engine
temperature
.
See
Table
a
.
Turn
the
ignition
on
.

If
the
gauge
needle
moves
upward,
the
sender
is
faulty
.
If
the

gauge
does
not
respond,
the
wiring
to
the
gauge
is
broken
(open
circuit)
or
the
gauge
itselfis
faulty
.

WARNING
-

1996
and
laten
models
are
OBD
11
compliant
.
Dis-
connecting
electrical
connectors
wíth
the
ignition
turned
on
may
set
fault
codes
in
the
ECM
.
It
is
rec-
ommended
that
you
leave
the
diagnosis
of
faults
in
the
coolant
temperature
sensorsystem
to
the
BMW
dealer
service
department
which
has
specialized
OBD
11
scan
tool
equipment
.

If
the
gauge
needle
reads
too
high
when
the
engine
is
cold,
remove
the
harness
connector
from
the
sender
.
Turn
the
igni-

tion
on
.
lf
the
gauge
needle
position
does
not
change,
the
wir-

ing
or
the
gauge
is
shorted
to
ground
.
If
the
gauge
needle

drops,
the
sender
is
faulty
and
should
be
replaced
.
When
re-

placing
a
faulty
coolant
temperature
sender,
the
gasket
ring
on
the
sender
should
also
be
replaced
.

Tightening
Torque

"
Temperature
gauge
sender
to
engine
18
Nm
(13
ft-Ib)

Cooling
fan,
testing

NOTE-

OnM44
engines
with
manual
transmission,
the
primary
electric
cooling
fan
is
mounted
on
the
engine
side
of
the
radiator
and
is
controlled
by
the
engine
control
module
(ECM)
.
Troubleshooting
thiscircuit
should
be
left
to
an
authorized
BMW
dealer
with
the
proper
diagnostic
equipment

An
otherwise
sound
cooling
system
may
still
overheat,
par-
ticularly
with
prolonged
idling,
due
to
a
failure
of
the
coolíng

fan(s)
.

The
belt-driven
cooling
fan
is
controlled
by
a
temperature
dependent
viscous
clutch
.
A
failed
fan
clutch
may
affect
air
flow
through
the
radiator
resulting
in
overheating
orpossibly
overcooling
.
Speed

Low
sp
High
s

With
the
engine
off,
check
thefan
clutch
by
spinning
thefan
.



eed
The
fan
should
spin
on
the
clutch
with
some
resistance
.



peed
Check
for
signs
of
leaking
fluid
from
the
clutch
.
If
thefan
free-
wheels
with
no
resistance,
cannot
be
tu
rned
by
hand,
or
there
are
signs
of
oil
leakage,
the
clutch
should
be
replaced
.

TROUBLESHOOTING

Fig
.
3
.



Radiatorcooling
fan
temperature
switch
(arrow)
.

WARNING
-

"
Use
caution
when
testing
the
electric
cooling
fan(s)
and
coolant
temperature
switch
.
Keep
hands
and
wires
clear
of
thefan
blades
.
The
cool-
ing
fan(s)
can
run
any
time
the
ignition
is
ON
.

"
For
greatest
safety,
coolíng
fan
and
coolant
tem-perature
switch
tests
shouldbe
performed
on
acoldengine
with
the
air
conditioning
off
.

Table
b
.
Auxiliary
Cooling
Fan
Switching

Temperatures

Switching
temperature
196°F(91°C)
210°F(99°C)

0012506

If
a
faulty
thermostat,
trapped
air,
or
a
restriction
in
the
sys-
tem
is
not
allowing
the
coolant
to
circulate
through
the
radia-
tor,
the
temperature
switch
will
not
close
and
the
auxiliary
cooling
fan
will
not
run
.
Before
making
the
tests
described
be-
low,
make
sure
the
thermostat
is
operating
correctly
as
de-
scribed
earlier
.
The
normal
switching
temperatures
for
the

dual
-speed
switch
are
listed
in
Table
b
.