Fuel pump wiring BMW 325i 1994 E36 Workshop Manual
[x] Cancel search | Manufacturer: BMW, Model Year: 1994, Model line: 325i, Model: BMW 325i 1994 E36Pages: 759
Page 3 of 759
General
Data
and
010
FundamentalsfortheDo-lt-YourselfOwner
Maintenance
020
Maintenance
Program
Engine
Transmission
Suspension,
Steering
and
Brakes
4
Body
100
Engine-General
110
Engine
Removal
and
Installation
113
Cylinder
Head
Removal
and
Installation
116
Cylinder
Head
and
Valvetrain
117
Camshaft
Timing
Chain
119
Lubrication
System
200
Transmission-General
210
Clutch
230
Manual
Transmission
510
Exterior
Trim,
Bumpers
520
Seats
Bo
y
Equipment
512
DoorWTdws
540
nr
t
513
InteriorTrim
541
Convertible
Top
515
Central
Locking
and
Anti-Theft
600
Electrical
System-General
620
Instruments
Electrical
S
stem
610
Electrical
Component
Locations
630
Exterior
Lighting
611
Wipers
and
Washers
640
Heating
and
Air
Conditioning
6
612
Switches
and
Electrical
Accessories
650
Radio
Equipment
and
720
SeatBelts
Accessories
721
Airbag
System
(SRS)
Electrical
Wiring
Diagrams
Foreword
.
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...
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.
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.
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v
Warnings
and
Cautions
.....
.
...
.
.
.
.
.
..........
.
...
.
.
.
.
.
......
.
.........
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.
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.
.
.
.
.
.vii
Index
..............
.
.
.
.....
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...
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.
.
.
........
.
.
.
..
back
of
book
300
Suspension,
Steering
and
330
RearSuspension
Brakes-General
331
Final
Drive
310
Front
Suspension
340
Brakes
320
Steering
and
Wheel
Alignment
400
Body-General
411
Doors
410
Fenders,
Engine
Hood
412
Trunk
Lid
120
Ignition
System
121
Battery,Starter,
Alternator
130
Fue¡
Injection
160
Fuel
Tank
and
Fuel
Pump
170
Radiator
and
Cooling
System180
Exhaust
System
240
Automatic
Transmission
250
Gearshift
Linkage
260
Driveshaft
Page 47 of 759
ignition
Table
b
.
Engine
Management
Systems
engine
has
high
mileage
.
Engine
1
System
4-cylinder
engines
M42
(1992-1995)
Bosch
DME
Ml
.7
M44
(1996-1998)
Bosch
DME
M5
.2
(OBD
II)
6-cylinder
engines
M50
(1992)
Bosch
DME
M3
.1
M50
VANOS
(1993-1995)
Bosch
DME
M3
.3
.1
M52
(1996-1998)
Siemens
MS41
.1
(OBD
II)
S50US
(1995)
Bosch
DME
M3
.3
.1
S52US
(1996-1998)
Siemens
MS41
.1
(OBD
II)
Both
the
4-cylinder
and
6-cylinder
engines
use
a
distributor-
less
ignition
system
with
individual
ignition
coils
for
each
cylin-
der
.
FuelDelivery
Pressurized
fuel
from
the
in-tank
fuel
pump
is
injected
via
solenoid-type
fuel
injectors
.
The
ECM
controls
the
opening
and
closing
of
the
injectors
by
switchingthe
ground
side
of
each
injector
circuit
.
The
exact
amount
of
fuel
injected
is
de-
termined
by
the
amount
of
timethe
injectors
are
open
.
Cooling
System
Whenever
the
engine
is
running,
acoolant
pump
circulates
coolant
through
the
engine
and,
if
either
heater
control
valves
are
open,
through
the
heater
core
in
the
passenger
compart-
ment
.
The
coolant
absorbs
excess
heat
and
carries
it
to
the
ra-
diator
where
it
is
transferred
into
the
passing
airstream
.
A
thermostat
controls
the
flow
of
coolant
through
the
radiator
based
on
engine
temperature
.
Lubrication
System
The
lubrication
system
is
pressurized
whenever
theengine
is
running
.
The
oil
pump
draws
oil
through
a
pickup
in
the
bot-
tom
of
the
oil
pan,thenforces
it
through
a
replaceable
oil
filter
and
finto
the
engine
oíi
passages
.
On
4-cylinder
engines,
the
oil
pump
is
mounted
to
the
front
engine
cover
.
On
6-cylinder
engines,thechain-driven
oil
pump
is
bolted
to
the
bottom
of
the
cylinder
block
.
A
pressure
relief
valve
limits
the
maximum
system
pres-
sure
.
A
bypass
valve
prevents
the
oil
filter
from
bursting
and
insures
engine
lubrication
should
the
filter
become
plugged
.
See
119
Lubrication
System
for
additional
information
.
ENGINE-GENERAL
100-
5
Various
versions
of
DME
systems
are
usedon
thecars
cov-
MECHANICAL
TROUBLESHOOTING
ered
by
this
manual
.
See
Table
b
.
Each
system
is
highly
adaptive
to
compensate
for
things
suchasengine
wear
and
When
troubleshooting
an
engine
that
fails
to
start
or
runs
vacuum
leaks
.
poorly,
first
check
its
mechanical
condition-particularly
if
the
Warnings
and
Cautions
For
personal
safety,
as
well
asthe
protection
of
sensitive
electronic
components,
the
following
warnings
and
cautions
must
be
adhered
to
during
all
troubleshooting,
maintenance,
and
repairwork
.
WARNING
-
"
The
ignition
system
produces
high
voltages
that
can
be
fatal
.
Avoid
contact
with
exposed
termi-
nals
anduse
extreme
caution
when
working
on
a
car
with
the
ignition
switched
on
or
the
engine
running
.
"
Do
not
touch
or
disconnect
any
high
voltage
ca-
bles
from
the
coil,
distributor,
orspark
plugs
while
the
engine
is
running
or
being
cranked
by
the
starter
"
Connect
and
disconnect
the
engine
manage-
ment
system
wiring
and
test
equipment
leads
only
when
the
ignition
is
switched
off
.
"
Gasoline
is
highly
flammable
and
its
vapors
are
explosive
.
Do
not
smoke
or
work
on
a
car
near
heaters
or
other
fire
hazards
when
diagnosing
and
repairing
fuel
system
problems
.
Have
a
fire
extínguisher
available
in
case
of
an
emergency
.
"
Disconnecting
the
battery
may
erase
fault
code(s)
stored
in
control
module
memory
.
Using
special
BMW
diagnosnnc
equipment,
check
for
fault
codes
prior
to
disconnecting
the
battery
cables
.
If
the
Check
Engine
lightis
illuminated,
see
On-
Board
Diagnostics
(OBD)
forfault
code
infor-
mation
.
If
any
other
system
faults
havebeen
de-tected
(indicated
byan
illuminated
warning
light),
see
an
authorized
BMW
dealer
.
CAUTION-
"
Prior
to
disconnecting
the
battery,
read
the
bat-
tery
disconnection
cautions
gíven
at
the
front
of
this
manual
on
page
viii
.
"
Do
notconnect
any
test
equipment
that
delivers
a
12-volt
power
supply
to
terminal15
(+)
of
the
ignition
coil
.
The
current
flow
may
damage
the
ECM
.
In
general,
connect
test
equipment
only
as
specified
by
BMW,
this
manual,
or
the
equip-
ment
maker
.
"
Do
not
disconnect
the
battery
with
the
engine
running
.
Do
notrunthe
engine
with
any
of
the
sparkplug
wires
disconnected
.
MECHANICAL
TROUBLESHOOTING
Page 52 of 759
100-
1
0
ENGINE-GENERAL
Table
d
.
OBD
I
Fault
(Blink)
Codes
(continued)
(1992-1995
modeis
only)
Graphic
representation
of
flashing
Check
Engine
light
fault
code
:
1221
-
;
5
Seconds
.
;--~
2
.5
r
----------------
Check
Engine
light
on
Fault
code
and
meaning
Corrective
action
Check
Engine
light
off
Code
1243
:
Crankshaft
position
sensor
(DME
3
.3
.1
only)
Test
crankshaft
position/rpm
sensor
and
wiring
from
sensor
lo
DME
control
module
.
Repair
Group
120
Code
1244
:
Camshaft
position
sensor
(DME
3
.3
.1
only)
Test
camshaft
position
sensor
and
wiring
fromsensor
to
DME
con-
trol
module
.
Repair
Group
130
Code
1245
:
Electronic
transmission
control
intervention
(DME
3
.3
.1
Check
wiring
between
DME
control
module
and
auto
.
transmission
only)
control
module
Code
1247
:
Ignition
secondary
monitor
(DME
3
.3
.1
only)
Check
secondary
voltage
lo
ignition
coils
.
Check
wiringat
ignition
coils
.
Repair
Group
120
Code
1251
:
Fuel
injector
#1
(DME
3
.113
.3
.1
only)
1
Test
injector
operation/signal
lo
injector
.
Repair
group130
Code
1252
:
Fuel
injector
#2
(DME
3
.113
.3
.1
only)
Test
injector
operation/signal
lo
injector
.
Repair
group130
Code
1253
:
Fuel
injector
#3
(DME
3
.1/3
.3
.1
only)
Test
injector
operation/signal
to
injector
.
Repair
group130
Code
1254
:
Fuel
injector
#4
(DME
3
.1/3
.3
.1
only)
Test
injector
operation/signal
to
injector
.
Repair
group
130
Code
1255
:
Fuel
injector
#5
(DME
3
.1/3
.3
.1
only)
Test
injector
operation/signal
to
injector
.
Repair
group130
Code
1256
:
Fuel
injector
#6
(DME
3
.1/3
.3
.1
only)
Test
injector
operation/signal
lo
injector
.
Repair
group130
Code
1261
:
Fuel
pump
control
Test
fuel
pump
relay
and
fuel
pump
circuit
.
Repairgroup
160
Code
1262
:
Idle
speed
control
Test
idleair
controlvalve
and
signalto
valve
.
Repair
Group
130
Code
1263
:
Fuel
tank
evaporative
(EVAP)
system
Test
EVAP
purge
valve
.
Repair
Group
160
Code
1264
:
Oxygen
sensor
heater
1
Test
oxygen
sensorheater
and
heater
relay
.
Repair
group
130
Code
1265
:
Check
engine
lamp
(DME
3
.3.1
only)
1
Test
for
faulty
bulb
or
wiring
.
Electrical
Wiring
Diagrams
Code
1266
:
VANOS
(DME
3
.3
.1
only)
1
Test
VANOS
solenoid
.
Check
for
signal
to
VANOS
solenoid
.
Code
1267
:
Air
pump
relay
control
(DME
3
.3
.1
only)
Test
air
pump
relay
and
wiring
(where
applicable)
Electrical
Wiring
Diagrams
Code
1271
:
Ignition
coil
#1
(DME
3
.3.1
only)
Test
ignitioncoil
and
wiring
toignitioncoil
.
Repair
Group
120
Code
1272
:
Ignition
coil
#2
(DME
3
.3.1
only)
Test
ignitioncoil
and
wiring
loignitioncoil
.
Repair
Group
120
Code
1273
:
Ignition
coil
#3
(DME
3
.3.1
only)
Test
ignitioncoil
and
wiring
loignitioncoil
.
Repair
Group
120
Code
1274
:
Ignítion
coil
#4
(DME
3
.3.1
only)
Test
ignitioncoil
and
wiring
toignitioncoil
.
Repair
Group
120
Code
1275
:
Ignitioncoil
#5
(DME
3
.3.1
only)
Test
ignition
coil
and
wiring
loignitioncoil
.
Repair
Group
120
Code
1276
:
Ignition
coil
#6
(DME
3
.3.1
only)
Test
ignitioncoil
and
wiring
loignitioncoil
.
Repair
Group
120
Code
1281
:
DME
control
module
memory
supply
(DME
3
.3
.1
only)
Check
voltage
supply
from
battery
lo
DME
control
module
.
Electri-
Code
1282
:
Fault
code
memory
(DME
3
.3.1
only)
Check
DME
control
module
inputs/outputs
.
Control
module
may
be
faulty
.
Repair
Group
130
Code
1283
:
Fuel
injector
output
stage
(DME
3
.3
.1
only)
Check
DME
control
module
inputs/outputs
.
Control
module
may
be
faulty
.
Repair
Group
130
DRIVEABILITY
TROUBLESHOOTING
cal
Wiring
Diagrams
Page 55 of 759
If
a
battery
cableconnection
hasno
visible
faults,
but
is
still
suspect,
measure
the
voltage
drop
across
the
connection
.
A
large
drop
indicates
excessive
resistance,
meaning
the
con-
nection
is
corroded,
dirty,
or
damaged
.
Clean
or
repair
the
connection
and
retest
.
NOTE-
For
instructions
on
conducting
a
voltage
drop
test,
and
other
general
electrical
troubleshooting
information,
see600
Electrical
System-General
.
Wiring
and
Harness
Connections
The
electronic
fuel
injection
and
ignition
systems
operate
at
low
voltage
and
current
values,
making
them
sensitive
to
small
increases
in
resistance
.
The
electrical
system
is
routine-
ly
subjected
to
corrosion,
vibration
and
wear,
so
faults
or
cor-
rosion
in
the
wiring
harness
and
connectors
are
common
causes
of
driveability
problems
.
Visually
inspect
all
wiring,
connectors,
switches
and
fuses
in
the
system
.
Loose
or
damaged
connectors
can
cause
inter-
mittent
problems,
especially
the
smallterminals
in
the
ECM
connectors
.
Disconnect
the
wiring
harness
connectors
to
check
for
corrosion
;
and
use
electrical
cleaning
spray
to
re-
move
contaminants
.
Often,
simply
disconnecting
and
recon-
necting
a
dirty
connector
several
times
will
clean
the
terminals
and
help
to
reestablish
good
electrical
contact
.
If
a
wiring
harnessconnectorhasno
visible
faults,
but
is
still
suspect,
measure
the
voltage
drop
across
the
connector
.
A
large
drop
indicates
excessive
resistance,
meaning
the
con-
nector
is
corroded,
dirty
or
damaged
.
Clean
or
repair
the
con-
nector
and
retest
.
Ground
Connections
For
any
electrical
circuit
to
work,
it
must
make
acomplete
path,
beginning
at
the
positive
(+)
battery
terminal
and
ending
at
the
negative
(-)
terminal
.
The
negative
(-)
battery
cable
is
attached
to
the
car's
chassis
.
Therefore,
any
wireor
metal
part
attached
to
the
chassis
provides
a
good
ground
path
back
to
the
negative
(-)
battery
terminal
.
Poorground
connections
are
amajor
source
of
driveabílity
problems
.
If
any
of
themainground
connections
for
the
igni-
tion
system
or
the
fuelinjection
system
are
faulty,
the
in-
creased
resistance
in
that
circuit
will
cause
problems
.
Visually
inspect
al¡
ground
wires
and
connections
for
breaks,
looseness
or
corrosion
.
Be
careful
because
wires
sometimes
break
internally
or
in
areas
not
easily
visible
.
The
main
grounds
for
the
DME
system
are
shown
in
Fig
.
11,Fig
.
12,
and
Fig
.
13
.
Also
check
the
main
fuel
pump
ground
in
the
center
console,
below
the
emergency
brake
handle
.
If
a
ground
connection
has
no
visiblefaults,
but
is
still
suspect,
measure
the
voltage
drop
acrossthe
connection
.
A
large
drop
indicates
high
resistance,
meaning
the
connection
is
corroded,
dirty
or
damaged
.
Clean
or
repair
the
connection
and
retest
.
ENGINE-GENERAL
100-
1
3
UU,~uyi
Fig
.
11
.
Mainground
(arrow)
for
engine
management
system
.
Grounds
are
in
right
rear
of
engine
compartment
.
Fig
.
12
.
Mainground
for
ignition
coils
on
MS
41
.1
engine
manage-
ment
system
(arrow)
.
DRIVEABILITY
TROLIBLESHOOTING
Page 61 of 759
14
.
Unbolt
power
steering
fluid
reservoir
from
íts
mounting
bracket
.
Use
stiff
wire
to
hang
reservoir
to
one
side
.
Do
not
disconnect
fluid
lines
.
15
.
Remove
power
steering
pump
drive
belt
and
remove
pump
from
its
mounting
bracket
.
Use
stiff
wire
to
hang
pump
from
body
.
16
.
On
cars
with
automatic
transmission
remove
front
and
rear
brackets
holding
automatic
transmission
cooler
linesto
engine
.
17
.
Remove
A/C
compressor
from
its
mounting
bracket
without
disconnecting
any
refrigerantlines
.
See
Fig
.
5
.
ENGINE
REMOVAL
AND
INSTALLATION
110-
3
21
.
Remove
front
exhaust
pipefrom
exhaust
manifold
.
See
Fig
.
6
.
22
.
Install
an
engine
lifting
device
and
raise
engine
until
its
weight
is
supported
.
Remove
nuts
and
ground
strap
from
left
and
right
engine
mounts
.
0011967
Fig
.
6
.
Front
exhaustpipe
to
exhaust
mounting
nuts
(arrows),
as
viewed
from
below
on
4-cylinder
engine
.
23
.
Carefully
raíse
engine
out
of
car,
checking
for
any
wir-
ing
harnesses,
fuel
lines,
or
mechanical
parts
that
might
become
snagged
as
engine
is
removed
.
24
.
Installation
is
reverse
of
removal,
noting
the
following
:
"
Replace
all
gaskets,
O-rings
and
seals
.
"
Change
engine
oil
and
filter
and
check
al¡
other
fluid
levels
.
See020
Maintenance
Program
.
"
Refill
and
bleed
cooling
system
.
See
170
Radiator
and
Cooling
System
.
"
Insta¡¡
the
front
exhaust
pipes
using
new
gaskets
and
self-locking
nuts
.
Use
copper
pasteon
threads
.
See
180
Exhaust
System
.
Tightening
Torques
"
Coolant
drain
plug
to
cylinder
block
.
25
Nm
(18
ft-Ib)
Fig
.
5
.
A/
C
compressor
mounting
bolts
(arrows)
.
"
Engine
mount
to
subframe
M8
......:...
..
..
..
......,:..
22
Nm
(17
ft
-
1b)
,
18
.
Move
A/C
compressor
out
of
way
without
distorting
or
M10
.
...
.
..
...
.
.
...........
45
Nm
(33
ft'-Ib)
damaging
any
lines
.
Support
compressor
by
hanging
it
"
Intake
manifold
to
cylinder
head
from
chassis
using
stiff
wire
.
M7
.....
.
..
...
..
..
...........
15
Nm
(11
ft-Ib)
M8
...
.
.
.
..
..
...
..
...........
22
Nm
(16
ft-Ib)
19
.
Disconnect
wiring
from
starter
and
alternator
.
Move
`
"
Radiator
cooling
fan
to
coolant
pump40
Nm
(30
ft-Ib)
wiring
harness
out
of
way
.
See
121
Battery,
Starter,
"
Radiator
drain
screw
to
radiator
...
2
.5
Nm
(22
in-lb)
Alternator
.
"
Wiring
to
alternator
(M8
nut)
........
12
Nm
(9
ft-1b)
"
Wiring
to
starter
20
.
Remove
oil
dipstick
guide
tube
.
Note
O-ring
at
base
of
M6
nut
..
.
..
..
...
..
...........
.
:5
Nm
(44
in-lb)
tube
when
removing
.
M8
nut
..
.
..
..
...
..
............
12
Nm
(9
ft-Ib)
ENGINE
REMOVAL
AND
INSTALLATION
Page 65 of 759
22
.
Move
A/C
compressor
out
of
the
way
without
distorting
26
.
Carefully
raise
engine
out
ofcar,
checking
for
any
wir-
or
damaging
any
lines
.
Support
compressor
by
hanging
ing,fuel
lines,
or
mechanical
parts
that
might
become
it
from
chassis
using
stiff
wire
.
snagged
as
engine
is
removed
.
23
.
Disconnect
wiring
from
starter
and
alternator
.
Move
27
.
Installation
is
reverse
of
removal,
noting
the
following
:
wiring
harness
out
of
the
way
.
See
121
Battery,
Start-
Replace
al¡
gaskets,
O-rings
and
seals
.
er,
Alternator
.
"
Change
engine
oil
and
filter
and
check
all
other
fluid
24
.
Remove
Fontexhaust
pipe
fromexhaust
manifold
.
See
levels
.
See
020
Maintenance
Program
.
"
Refill
and
bleed
cooling
system
.
See
170
Radiator
Fig
.
16
.
and
Cooling
System
.
"
Check
that
engine
drivebelts
properly
engage
the
pul-
ley
grooves
.
"
Install
the
Font
exhaust
pipesusing
new
gaskets
and
seif-locking
nuts
.
Use
copper
paste
on
threads
.
See
180
Exhaust
System
.
0012525
Fig
.
16
.
Front
exhaust
pipeto
exhaust
manifolds
mounting
nuts
on
6-
cylinder
engine
(arrows)
.
25
.
Install
an
engine
lifting
device
and
raise
engine
until
its
weight
is
supported
.
Remove
nuts
and
ground
strap
from
left
and
right
engine
mounts
.
ENGINE
REMOVAL
AND
INSTALLATION
110-
7
Tightening
Torques
"
Coolant
drain
plug
to
cylinder
block
.
25
Nm
(18
ft-Ib)
"
Engine
mount
to
subframe
M10
..
.
.
.
...
..............
..
.
45
Nm
(33
ft-Ib)
M8
..
..
.
..
................
...
22
Nm
(16
ft-Ib)
"
Intake
manifold
to
cylinder
head
M7
..
..
..
...
................
.
15
Nm
(11
ft-Ib)
M8
...
.
..
...
................
.
22
Nm
(16
ft-Ib)
"
Radiator
cooling
fan
to
coolant
pump40
Nm
(30
ft-Ib)
"
Radiator
drain
screw
to
radíator
...
2
.5
Nm
(22
in-lb)
"
Wiring
to
alternator
(M8
nut)
........
12
Nm
(9
ft-Ib)
"
Wiring
to
starter
M6
nut
.
..
...
..................
5
Nm
(44
in-lb)
M8
nut
.....
..
.
.
.
.
.............
12
Nm
(9
ft-Ib)
ENGINE
REMOVAL
AND
INSTALLATION
Page 148 of 759
130-2
FUEL
INJECTION
GENERAL
This
repair
group
covers
fuel
injection
system
component
testing
and
repair
.
Special
equipment
is
necessary
for
some
of
the
procedures
given
in
this
repair
group
.
If
you
do
not
have
the
equipment
required
to
do
the
job,
it
is
recommended
that
these
repairs
be
left
to
an
authorized
BMW
dealer
.
The
BMW
dealer
is
equipped
with
sophisticated
diagnostic
test
equip-
ment
that
is
capable
of
quicklypinpointing
hard-to-find
fuel
in-
jection
problems
.
NOTE-
"
Wiring
diagrams
for
the
engine
management
system,
can
be
found
at
the
rear
of
the
manual
under
Electri-
cal
Wiring
Diagrams
.
"
For
ignition
system
repairinformation,
see120
Igni-
tion
System
.
"
For
fuel
supply
system
testing
and
repair,
see160
The
engine
control
module
(ECM)
uses
electrical
signals
Fuel
Tank
and
Fuel
Pump
.
from
the
mass
air
flow
sensor,
the
air
and
coolant
temperature
sensors,
the
crankshaft
position/rpm
sensor,
the
knock
sen
Principies
Of
Operation
sors
and
the
oxygen
sensorsas
the
primary
inputs
to
electron-
ically
control
fuel
delivery
and
ignition
timing
.
There
are
five
versions
of
engine
management
systems
usedon
the
E36
cars
.
Each
has
the
same
basic
components
and
operating
principles
.
The
most
notable
difference
is
that
1996
and
later
cars
use
a
sophisticated
OBD
II-compliant
sys-
tem
.
See
Table
a
.
Table
a
.
Engine
Management
System
Variants
Engine
code/year
1
System
4-cy1inder
M42
(1
.8
I)
1992-1995
Bosch
DME
Ml
.7
M44
(1
.91)
1996-1998
~
Bosch
DME
M5
.2
(OBD
II)
6-cylinder
M50
1992
(2.5
I)
Bosch
DME
M3
.1
1993-1995
(2.5
I)
Bosch
DME
M3
.3.1
(VANOS)
M52
1996-1998
(3281-
2
.8
I)
Siemens
MS
41
.1
(OBD
II)
1998
(3231
-
2
.5
I)
Siemens
MS
41
.1
(OBD
II)
M-Power
S50US
(M3
-
3
.01)
1995
Bosch
DME
M3
.3
.1
S52US
(M3
-
3
.21)
1997-1998
Siemens
MS
41
.1
(0131)
11)
NOTE-
-
Descriptions
and
procedures
in
the
first
partof
this
re-
pairgroup
refer
to
all
the
various
engine
management
systems
.
"
Particulars
of
each
fuel
injection
system
are
treated
in
separate
sections
in
the
second
part
of
this
repair
group
.
GENERAL
Fig
.1
.
OBD
II
diagnostic
connector
locatíon
.
The
fuel
injection
system
is
completely
electronic
in
opera-
tion
.
Air
flow
is
measured
electronically
via
a
mass
air
flow
sensor
and
additional
sensors
supply
information
about
en-
gine
operating
conditions
.
The
ECM
calculates
the
amount
of
fuel
needed
for
the
correct
air-fuel
ratio
and
actuates
the
fuel
injectors
accordingly
.
The
amount
offuel
metered
to
theen-
gine
is
determined
by
how
long
the
injectors
are
open
.
Airintake
.
Air
entering
the
engine
passes
through
a
pleat-
ed
paper
air
filter
in
the
air
cleaner
.
Intake
air
volume
or
mass
is
then
measured
bya
mass
air
flow
(MAF)
sensor
.
In
al¡
ex-
cept
the
vane
type
sensor
(DME
M1
.7),
a
reference
current
is
used
to
heat
a
thin
wireor
film
in
the
sensor
when
the
engine
is
running
.
The
current
used
to
heat
the
wire/film
is
electroni-
cally
converted
into
a
voltage
measurement
corresponding
to
the
mass
of
the
intake
air
.
Table
b
.
Mass
Air
Flow
Sensor
Variants
System
Al
r
flow
sensor
type
Bosch
DME
M1
.7
Vane
(volume
sensor)
Bosch
DME
M3
.1
Hot
wire
(mass
sensor)
Bosch
DME
M3
.3
.1
Hot
film
(mass
sensor)
Bosch
DME
M5
.2
Hot
film
(mass
sensor)
Siemens
MS
41
.1
Hot
film
(mass
sensor)
"
The
16-pin
OBD
11
diagnostic
connector
is
located
on
NOTE-
the
lower
left
dashpanel
.
See
Fig
.
1
.
On
cars
equipped
wíth
tractioncontrol,
an
additional
throttle
valve
is
controlled
by
an
electronic
throttle
actu-
ator
(motor)
.
This
valve
is
used
for
engine
speed
inter
vention
.
Repair
information
forthis
system
is
notcovered
here
due
to
the
special
electrical
testing
equip-
ment
required
to
service
it
.
Page 153 of 759
ELECTRICAL
CHECKS
AND
COMPONENT
TESTING
Main
relay,
testing
The
main
relay
is
energized
via
the
engine
control
module
and
supplies
plus
(+)
power
to
the
many
of
the
engine
man-
agement
components
and
subsystems,
including
the
fuel
pump
relay
.
If
this
relay
is
faulty,
the
engine
will
not
start
.
1
.
With
ignition
off,
remove
main
relay
.
See
Fig
.
6
.
.
iommooommmoi
~
"""
Fuel
DME
sensor
CA
UTION-
Relay
positions
can
vary
.
Be
sure
to
confirm
relay
position
by
identífyíng
the
wiring
in
the
socket
us-
ingthe
wiring
diagramsfound
at
the
rearof
this
manual
.
0013034)
Fuel
pump
relay,
testing
FUEL
INJECTION
130-
7
87
851186
30
~j
1
.
Remove
fuel
pump
relay
from
its
socket
.
87661
Fig
.
7
.
Check
for
battery
voltage
at
main
relay
terminals
30
and
86
.
Voltage
should
be
present
at
all
times
.
4
.
With
ignition
on
and
relay
installed,
check
for
battery
voltage
at
terminals
87
.
"
If
battery
voltage
is
present,relay
has
energized
and
is
functioningcorrectly
.
"
lf
battery
voltage
is
not
present
and
al¡
earlier
tests
are
OK,
relay
is
faulty
and
should
be
replaced
.
Fig
.
6
.
Engine
management
relays
in
the
power
distribution
box,
left
rear
of
engine
compartment
.
The
fuel
pump
relay
is
located
in
the
power
distribution
box
.
Refer
to
Fig
.
6
.
The
ECM
supplies
power
to
the
coil
side
of
the
fuel
pump
re-
lay
.
During
starting,
the
fuel
pump
runs
as
long
as
the
ignition
switch
isin
the
start
position
and
continues
to
run
once
theen-
gine
starts
.
If
the
relay
ís
faulty
the
fuel
pump
will
notrun
.
2
.
Check
for
voltage
at
terminal
30
and
terminal
86
of
re-
¡ay
socket
.
See
Fig
.
7
.
2
.
With
key
off,
check
for
batteryvoltage
at
socket
terminal
"
If
battery
voltage
is
present
continue
testing
30
.
See
Fig
.
8
.
"
lf
battery
voltage
is
not
present
at
either
point,
check
large
red
wire
in
relay
socket
.
See
Electrical
Wiring
3
.
With
ignition
key
in
start
position
check
for
battery
volt-
Diagrams
.
age
at
terminal
86
.
NOTE-
4
.
With
ignition
key,
use
digital
multimeter
to
check
for
The
wiring
to
terminals
85
and
86
in
the
main
relay
may
ground
at
terminal
85
.
be
reversed
.
Electrically,
the
relay
functions
either
way
.
lf
voltage
ís
not
present
at
terminal
86,
check
for
volt-
NOTE-
age
at
terminal
85
.
The
ground
atterminal
85
is
switched
by
the
ECM
.
The
ECM
hamess
must
be
connected
to
check
the
3
.
Reinstall
relay
and
turn
ignition
on
.
Gainaccess
to
un-
switched
ground
connection
.
derside
of
relay
socket
and
check
for
ground
at
terminal
85
(brown
wire)
.
5
.
If
no
faults
are
found
up
tothis
point,
testfuel
pump
op-
"
lf
ground
is
present
continue
testing
.
eration
as
described
in
160
Fuel
Tank
and
Fuel
Pump
.
"
If
ground
is
not
present,
signal
from
ECM
is
missing
.
Check
wire
between
ECM
and
relay
.
If
no
faults
can
be
found,
ECM
may
be
faulty
.
ELECTRICAL
CHECKS
AND
COMPONENT
TESTING
Page 154 of 759
130-
8
FUEL
INJECTION
Fig
.
8
.
Fuel
pump
relayterminal
identification
.
1.
Peel
back
rubber
boot
on
oxygen
sensor
electrical
har-
ness
connector
(car
wiring
side)
.
With
connector
at-
Oxygen
sensor,
testing
tached
to
sensor,
connect
digital
voltmeter
to
pins
1
(BOSch
systems
only)
and
2
in
rear
of
connector
.
See
Fig
.
10
.
CAUTION-
"
The
information
inthis
sectionapplies
to
Bosch
engine
management
systems
only
.
"
The
Siemens
MS
41
.1
system
uses
resistive-type
oxygen
sensors
.
This
sensor
uses
a
5-volt
refer-
ence
signal
input
and
the
output
to
the
ECM
var-
ees
from
1-5
volts,
in
stepped
increments
based
on
oxygen
content
in
the
exhaust
.
NOTE-
"
On
pre-08D
11(1992-1995)
cars,
there
is
one
oxygen
sensor
mounted
upstream
of
the
catalytic
convert-
er(s)
in
the
exhaust
pipe
.
See
Fig
.
9
.
"
On
OBD
11
cars
(1996-1998)
cars,
there
is
one
oxygen
sensor
before
andone
after
each
catalytic
converter
.
"
OnM52
and
S52US
engines,
the
front
pairof
oxygen
sensors
are
installed
in
the
exhaust
manifolds
.
The
oxygen
sensor
providesan
input
voltage
signal
(0-1
VDC)
to
the
ECM
based
on
the
oxygen
content
in
the
exhaust
gas
.
TO
generate
voltage,
the
sensor
temperature
must
exceed
575°F
(300°C)
.
Therefore
it
ís
electrically
heated
.
NOTE-
"
The
test
given
below
is
not
a
conclusive
test
of
oxygen
sensor
efficiency
and
does
not
test
how
quickly
the
oxygensensor
can
react
to
changing
conditions
.
"
Pin
numbers
and
wirecolors
can
vary
.
Always
check
the
wiring
diagrams
to
conflrm
wire
color
and
pinas-
signment
.
ELECTRICAL
CHECKS
AND
COMPONENT
TESTING
0013135
Fig
.
9
.
Oxygen
sensor
location
(arrow)
ahead
of
catalytic
converter
.
3181
model
with
M42
engine
shown
.
1
.
Black
(ground)
2
.
Grey
(signal)
4
.
White
(heater
circuit)
3
.
White
(heater
circuit)
0013189
Fig
.
10
.
Oxygen
sensor
connector
terminal
identification
(sensor
sede)
.
Terminals
numbers
are
molded
into
connector
.
2
.
Start
engine
.
Oxygen
sensorshould
start
to
output
a
fluctuating
voltage
within
a
short
period
.
If
voltage
is
in-
correct,
turn
engine
off
and
check
preheater
circuit
as
described
below
.
WARNING
-
Exhaust
manifolds
and
pipes
can
be
hot
enough
to
cause
serious
burns
.
Wear
suitable
heavy
gloves
and
other
appropriate
protection
.
Page 155 of 759
Oxygen
Sensor
FUEL
DELIVERY
TESTS
FUEL
INJECTION
130-
9
"
Voltage
at
¡dle
..
.
..
..
....
0
.2
to
0
.8
VDC,
fluctuating
Checking
fuel
delivery
is
afundamental
part
of
trouble-
shooting
and
diagnosing
the
engine
management
system
.
Fuel
pressure
directly
influences
fuel
delivery
.
An
accurate
NOTE-
fuel
pressure
gauge
will
be
needed
to
make
the
tests
.
To
check
sensorresponse
to
lean
and
rich
mixtures,
createenairleak,
orpull
vacuumhoseofffue¡
pressure
There
are
three
significant
fuel
delivery
values
to
be
mea-
regulator
to
increase
fuel
pressure
.
sured
:
3
.
Separate
sensorharness
connector
from
sensor
.
Check
for
battery
voltage
between
terminals
3
and
4
(green
wire
and
brown
wire)
in
main
wiring
harness
side
of
con-
nector
with
engine
running
.
If
voltage
is
not
present,
check
oxygen
sensor
heater
relay
.
See610
Electrical
Component
Locations
.
4
.
Check
heater
element
resistance
between
terminals
3
and
4
in
sensor
side
of
connector
.
If
element
is
electri-
cally
open
(no
continuity),
replace
sensor
.
NOTE-
The
oxygen
sensor
heater
relay
is
mounted
in
the
main
power
distributfon
box
in
the
left
rear
of
the
engine
com-
partment
.
Refer
to
Fig
.
6
.
The
heater
relay
is
energized
wíth
positive
(+)
battery
voltage
from
the
main
relayanda
switched
ground
from
the
ECM
.
See
Electrical
Wir-
ing
Diagrams
.
"
Oxygen
sensor
to
exhaust
pipe
...
..
55
Nm
(41
ft-Ib)
"
System
pressure-created
by
the
fuel
pump
and
main-
tained
by
the
pressure
regulator
.
"
Fuel
delivery
volume-created
by
the
fuel
pump
and
af-
fected
by
restrictions,
suchasclogged
fuel
filter
.
"
Residual
pressure-the
pressure
maintained
in
the
closed
system
after
the
engine
and
fuel
pump
are
shut
off
.
Procedures
for
measuring
the
first
two
quantities
arede-
scribed
in
160
Fuel
Tank
and
Fuel
Pump
.
Residual
fuel
pres-
sure
is
checked
using
the
procedure
detailed
later
in
this
group
.
Operating
fuel
pump
fortests
To
operate
the
fuel
pump
for
testing
purposes
without
hav-
íng
to
runthe
engine,
the
fuel
pump
relay
can
be
bypassed
to
power
the
pump
directly
.
Fuel
pump
relay
location
is
shown
in
Fig
.
6
.
5
.
¡f
oxygen
sensor
doesn't
produce
a
fluctuating
voltage
To
runthe
fuel
pump,
remove
the
fuel
pump
relay
and
con-
and
preheater
circuit
is
OK,
replace
sensor
.
nect
the
socket
for
relayterminal
30
to
the
socket
for
relay
ter-
mina¡
87
with
a
fused
jumper
wire
.
After
completing
the
tests,
NOTE-
remove
the
jumper
wire
.
If
not
already
applied,
coat
the
oxygen
sensor
threads
with
an
anti-seize
compound
before
installation
.
Do
not
CAUTION-
getthe
compound
on
the
sensor
tip
.
"
Relay
locations
may
vary
.
Use
care
when
identi-
fying
relays
and
making
electrical
checks
at
the
fuselrelay
panel
.
See
610
Electrical
Compo
Tightening
Torque
nent
Locations
for
additional
relay
information
.
"
The
fuel
pump
relay
has
a
1
.5
mm2
red
wire
at
ter-
minal
30
in
the
relay
socket
.
Terminal
87
has
a
1
.5
mm
2
greenlviolet
wire
.
See
Electrical
Wiring
Di-
agrams
for
additional
wiring
information
.
NOTE-
Thejumper
wire
should
be
1.5
mm2
(14
ga
.)
and
in-
clude
an
in-line
tuse
holder
with
a15
amp
tuse
.
To
avoid
fuselrelay
panel
damage
from
repeated
connect-
ing
and
disconnecting,
also
include
a
toggle
switch
.
A
heavy-duty
jumper,
BMW
tool
no
.
61
3
050,
is
also
available
from
an
authorized
BMW
dealer
.
FUEL
DELIVERYTESTS