1994 BMW 325i air temperature sensor

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

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

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
.

GENERAL
.
.
.......
.
......
.
...
.
.
.
.
.
...
180-1



Exhaust
system,
removing
and
installing
.
...
.180-3

EXHAUST
SYSTEM
REPLACEMENT
.
...
180-1



Exhaust
manifolds,
removing
and
installing
.
.
.180-5

GENERAL

The
exhaust
system
is
designed
to
be
maintenance
free,
al-
though
regular
inspection
is
warranted
due
to
the
harsh
oper-
atingconditions
.
Under
normal
conditions,
the
catalytic

converter
does
not
require
replacement
unless
it
is
damaged
.

On
1996
and
later
cars,
a
pre-
and
post-catalytic
converter

oxygen
sensor
is
used
at
each
catalytic
converter
.
Be
sure
to

take
care
when
removingthe
system
not
to
damage
the
sen-



EXHAUST
SYSTEMREPLACEMENT
sors
.

See
130
Fuel
Injection
for
information
on
testing
oxygen

sensors
.

NOTE-

OnM52
engines,
two
resonator
pípes
(short
and
long)
are
incorporated
into
the
rear
muffler
assembly
.
See
Fíg
.
1
.
An
exhaust
flap
is
integrated
into
the
outlet
side
of
the
short
pipe
.
The
flap
is
operated
by
a
vacuum
ac-
tuator
via
the
Siemens
MS
41
.1
engine
control
mod-
ule)
.
The
flap
is
closed
at
engine
speeds
below
2,500
rpm
.
This
allows
exhaust
gasses
to
flow
through
the
long
resonator
pipe
and
reduce
noise
.
Above
2,500rpm,
the
exhaust
flap
is
open
(no
vacuum
applied
to
the
actuator)
and
allows
exhaust
gasses
to
flow
through
the
short
pipe
for
maximum
performance
.

180
Exhaust
System

0013101

Fig
.
1
.



Rear
muffler
(active
silencer
usedon
M52
engines)
.
Vacuum

operated
flap
(A)
changesbetween
short
and
long
pipes,
de-

pending
on
engine
speed
.

EXHAUST
SYSTEM



180-1

WARNING
-

Exhaust
gases
are
colorless,
odorless,
and
very
toxic
.
Run
the
engine
only
ín
a
well-ventilated
area
.
Immediately
repair
any
leaks
in
the
exhaust
system
or
structural
damage
to
the
car
body
that
might
al-
lowexhaust
gases
to
enter
the
passenger
compart-
ment
.

Exhaustsystem
components
are
detailed
in
Fig
.
2
through

Fig
.
4
.

New
fasteners,
clamps,rubber
mounts,
and
gaskets
should

be
used
when
replacing
exhaust
components
.
A
liberal
appli-
cationof
penetrating
oil
to
the
exhaustsystem
nuts
and
bolts
in
advance
may
make
removal
easier
.

WARNING
-

"
The
exhaust
system
and
catalytic
converter
op-
erate
at
high
temperatures
.
Allow
components
to
cool
before
servicing
.
Wear
protectíve
clothíng
to
prevent
bums
.
Do
not
use
flammable
chemicals
near
a
hot
catalytic
converter
.

"
Old,
corroded
exhaust
system
components
crumble
easíly
and
often
have
exposed
sharp
edges
.
To
avoid
injury,
wear
eye
protection
and
heavy
gloves
when
working
with
old
exhaust
parts
.

EXHAUST
SYSTEM
REPLACEMENT

T

1
.
Heater
valves
2
.
ABS
pedal
travel
sensor3
.
ABS
pump

Fig
.
10
.
Left
rear
of
engine
compartment
.

4
.
Main
engineharness
con-
nector
5
.
Power
distribution
box

ELECTRICAL
COMPONENT
LOCATIONS
610-5

0013202
0013226

Fig
.
11
.
M42
engine
idie
speed
control
valve
(arrow)
beneath
intake
manifold

0012421

Fig
.
12
.
M44
engine
intake
air
temperature
(¡Al)
sensor
in
air
filter
housing

Fig
.
13
.
M50/S50U
S
engine
intake
air
temperature
(IAT)
sensor
(1)
and
throttle
position
sensor
(2)
.

301180

0012724

Fig
.
14
.
M52/S52U
S
engine
intake
air
temperature
(IAT)
sensor
in
bot-
tom
of
intake
manifold
(throttle
housing
shown
removed)
.

COMPONENT
LOCATIONS

Fig
.
19
.
M44
engine
coolant
temperature
(ECT)
sensor
(arrow)
.



Fig
.
22
.
Headlight
ground
at
left
frontof
engine
compartment
(arrow)
.

0012704

Fig
.
20
.
M52
engine
coolant
temperature
(ECT)
sensor
(A)
is
located
beneath
top
enginecover
(B)
and
crankcase
vent
hose
(C)
.

uu12700

Fig
.
21
.
M52
throttle
position
sensor
(A),
idle
speed
control
valve
(B),
and
secondary
air
pump
(C)
.

ELECTRICAL
COMPONENT
LOCATIONS



610-7

00119s4



0013131

uvijijo
Fig
.
23
.
Mainground
at
right
strut
tower
(A)
.
B
is
negative
jumper
con-
nection
.

COMPONENT
LOCA
TIONS

610-10



ELECTRICAL
COMPONENT
LOCATIONS

Component



Model
Year



Location



Refer
to

ABS
Hydraulic
Control
Unit



1992-1998



Left
rear
engine
compartment
undermaster
cylinder



Fig
.
7
.
Fig
.
10
.

ABS
Hydraulic
Control
Unit
Relay



1992-1998



Power
distribution
box



Fig
.
2
.

ABS
Pedal
Travel
Sensor



1992-1998



On
brake
booster
beside
master
cylinder



Fig
.
10
.

ABS
Relay



1992-1998



Power
distribution
box



Fig
.
2
.

ABS/AS
T
(Traction)
Control
Module



1992-1998



Behind
glove
compartment



Fig
.
8
.
Fig
.
9
.

ABS
Speed
Sensor,
Left
Front



1992-1998



Left
front
steering
arm



Fig
.
31
.
Wheel

ABS
Speed
Sensor,
Left
Rear



1992-1998



Left
rear
trailing
arm
Wheel

ABS
Speed
Sensor,
RightFront



11992-1998



Right
front
steering
arm
Wheel

ABS
Speed
Sensor,
Right
Rear



1992-1998



I
Left
rear
trailing
arm
Wheel
1

A/C
Compressor



1
1992-1998



(
Rightlower
frontof
engine

A/C
Compressor
Control
Relay



1
1992-1998
1992-1998
1992-1998

A/C
Control
Module

A/C
Evaporator
Temperature
Sensor
A/C
Pressure
Switch



1992-1998



Right
frontof
engine
compartment

A/C
Program
Switch



1992-1998



Center
of
dash
below
radio

A/CRecharging
Ports



1992-1998



Right
rear
engine
compartment



Fig
.
16
.

Air
Flow
Sensor



1992-1998



Between
throttle
housing
&
filter
housing



Fig
.
7
.

Airbag
Contact
Slip
Ring



1992-1998



Rear
ofsteering
wheel

Airbag,
Driver



1992-1998



In
center
of
steering
wheel



Fig
.
25
.

Airbag,
Passenger



1994-1998



Right
front
of
dash
above
glove
compartment



Fig
.
26
.

Airbag,
Side-Impact



1997-1998



Behind
right/left
front
door
panel
Airbag
Control
Module
(Basic)



1992-1993



Behind
glove
compartment



Fig
.
8
.
Fig
.
9
.

Airbag
Control
Module
(ZAE)



1994-1998



On
center
tunnel
under
rear
seat
cushion

Airbag
Crash
Sensor,
Airbag



1992-1993



On
righUleft
front
strut
tower
Airbag
Crash
Sensor,
Right/Left



1997-1998



Right/left
door
si¡¡
behind
front
seatSide
Impact

Alternator
(Generator)



1992-1998



Left
lowerfront
of
engine

Amplifier
Hi-fi



1992-1998



Left
front
side
of
luggage
compartment

Antenna
Amplifier
AM/FM



1992-1998



In
upper
left
side
C-pillar



Fig
.
27
.

COMPONENT
LOCA
TIONS

Table
a
.
E36
Component
Locations

Power
distribution
box



Fig
.
2
.

Behind
center
console

Left
sideof
heater
box

Continued

610-12



ELECTRICAL
COMPONENT
LOCATIONS

Table
a
.
E36
Component
Locations

Component



Model
Year



Location



Refer
to

Combination
(Stalk)
Switch



1993-1998



Left
sidesteering
column
(turn
signals/high-low
bean
switch)

Convertible
Top
ActuatingSwitch



1994-1998



Center
console

Convertible
Top
Control
Module



1994-1998



In
lower
left
C-pillar
behind
trim
panel

Convertible
TopEnd
Position
Switch



1994-1998



In
convertible
top
linkage

Convertible
Top
Motor



1994-1998



In
left
sideof
trunk
behind
trim
panel

Convertible
Top
Position



1994-1998



In
convertible
top
linkage
Microswitch
Convertible
Top
Storage
Lid
Lock



1994-1998



In
convertible
top
compartment
left
side
Motor

Convertible
Top
Storage
Lid



1994-1998



Inright
side
convertible
top
storage
lid
latch
Microswitch

Convertible
Top
Storage
Lid
Motor



1994-1998



In
left
side
of
trunk
behind
trim
panel

Coolant
Leve¡
Sensor
(if
applicable)



1992-1998



Bolted
on
radiator,
left
side

Coolant
Temperature
Sensor



1992-1998



Left
front
of
engine/cylinder
head



Fig
.
19
.
Fig
.
20
.

Cooling
Fan
Dual
Switch



1992-1998



Right
side
radiator



Fig
.
18
.

Cooling
Fan
Motor



1992-1998



Behind
front
grill

Crankshaft
Position/RPM
Sensor



1992-1995



At
front
crankshaft
pulley

Crankshaft
Position/RPM
Sensor



1996-1998



Left
rearof
crankcase

Crash
Sensor,
Airbag



1992-1993



On
right/left
frontstrut
tower

Crash
Control
Module



1992



Auxiliary
relay
panel

Crash
Control
Module



1993-1998



Driver's
side
footwell

Crash
Sensor,
Right/Left
Side



1997-1998



Right/left
door
sill
behind
front
seat
Impact
Airbag

Cruise
Control
Actuator



1992-1998



Left
front
of
engine
compartment



Fig
.
7
.

Cruise
Control
Module



1992-1998



Behind
glove
compartment



Fig
.
8
.
Fig
.
9
.

Data
Link
Connector



1992-1998



Right
sideof
engine



Fig
.
7
.

Digital
Motor
Electronics
(DME)



1992-1998



Right
rear
engine
compartment,
behind
bulkhead
panel



Fig
.
7
.
Control
Module

DoorLock
Heater



1993-1994



Left
front
doorhandle
DoorHandle
Switch



1994-1998



left
front
door

Drive-away
Protection
(EWS
II)



1/1995
-
1998



Behind
glove
compartment



Fig
.
8
.
Module



Fig
.
9
.

Dual
Coolant
Temperature
Sensor



1997-1998



Below
intake
manifold



Fig
.
19
.

COMPONENT
LOCATIONS

Fig
.
20
.

Electronic
Immobilizer
Control



(
1/1995-1998
~
Behind
glove
compartment



Fig
.
8
.
Module
(EWS
II)



Fig
.
9
.

Continued