Engine harness BMW 318i 1994 E36 Service Manual

130-20



FUEL
INJECTION

Fig
.
29
.
Throttleposition
sensor
terminal
identification
on
M50
engine
.

Tableg
.
Throttle
Position
Sensor
Tests

(DME3
.113
.3
.1)

Test
conditions



I
Terminals



I
Testvalue

Harness
connector



13
andground



15
VDC
(approx
.)
disconnected,
igni-



in
harness
tion
on



connector

Harness
connector



1
and3
at
sen-
14
k
ohms
(approx
.)
disconnected,
igni-



sor
terminals
tion
off

Throttle
plate
rotat-



1
and
2
at
sen-



Variable
from
1
-
4ked
from
¡dieto
full



sor
terminals



ohms
(approx
.)
with-
throttle
position



out
interruption



¡die
Speed
Control
Valve
Coil
Resistance
Values

"
M50/S50US
engine

NOTE-



Terminals
1
and
2
..
.
................
20
t
5
ohms

On
cars
with
tractioncontrol,
do
not
confuse
the
throttle



Terminals
2
and
3
...................
20
t5
ohms
position
sensor
on
the
main
throttle
body
with
the
throt-



Terminals
1
and
3
..
.
..
:
............
.40
t
5
ohms
tle
positionswitch
on
the
secondary
throttle
body,
where
applicable
.

¡die
speed
control
valve,
testing

¡die
speed
is
maintained
by
the
ECM
through
the
¡die
speed
control
valve
.
The
¡die
controlfunction
compensates
for
engine
load
and
engine
operating
conditions
.
¡die
speed
is
adaptive
through
the
ECM
and
no
¡die
speed
adjustments
can
be
made
.

NOTE-
Before
testing
the
valve,
confirm
that
the
throttle
position



The
idle
speed
controlvalve
receives
positive
(+)
bat-
sensor
is
working
correctly
.



tery
voltage
from
the
main
relay
.

BOSCH
DME
M3
.
1
AND
M3
.3
.1
COMPONENT
TESTS
AND
REPAIRS

NOTE-

"
The
tests
given
below
are
electrical
checks
only
.
They

do
not
check
the
mechanical
operation
of
the
valve
.
If
the
valve
is
suspected
of
causing
poor
idie,
substitut-
ing
a
known
good
valve
is
the
best
way
to
check
for
a
mechanical
fault
.

1
.
With
engine
running,
check
that
¡die
speed
control

valve
is
buzzing
.

2
.
Turn
on
A/C
or
shift
car
finto
drive
.
¡die
should
remain
steady
orincrease
slightly
.

3
.
If
valve
is
not
buzzing,or
if
¡die
decreases
in
step
2,

stop
engine
and
disconnect
harness
connector
from
valve
.
Check
resistance
of
valve
across
its
terminals
.

See
Fig
.
30
.
Test
values
are
listed
below
.

NOTE
-

If
you
suspect
an
intermittent
fault,
lightly
tapthe
valve
while
testing
resistance
.

11250

Fig
.
30
.
¡die
speed
control
valve
terminal
identification
.

4
.
With
valve
harnessconnector
disconnected,
check
for
battery
voltage
at
red/white
wire
in
connector
with
igni-

tion
tumed
on
.

"
If
there
is
no
voltage,
check
wiring
between
connec-
tor
and
main
relayterminal
87
.
See
Electrical
Wiring
Diagrams
.

5
.
If
voltage
is
presentas
described
above,
check
wiring
between
ECM
and
valve
.
If
no
wiring
faults
are
found,
check
ECM
signal
to
valve
.

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
.

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

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

130-26



FUEL
INJECTION

Throttle
position
sensor
(TPS),
replacing

The
throttie
position
sensor
is
located
on
the
side
of
the
throttie
housing
.
See
Fig
.
40
.

Fig
.
40
.
M52
engine
:
Throttle
position
sensor
(arrow)
.

1
.
Unplug
harness
connector
from
sensor
.

NOTE
-

On
cars
with
tractioncontrol,
do
not
confuse
the
throttieposition
sensor
on
the
main
throttie
body
wíth
the
throt-
tie
position
switch
on
the
secondary
throttie
body,
where
applicable
.

3
.
Installation
is
reverse
of
removal
.

¡die
speed
control
valve,
replacing

0012700b

The
¡die
speed
control
valve
is
mounted
on
the
underside
of
the
intake
manifoldadjacent
to
the
dipstick
tube
bracket
.
Ac-
cessing
the
valve
is
best
accomplished
by
first
removing
the
throttie
housing
.

1
.
Disconnect
intake
air
bootfrom
throttie
housing
.
Unbolt
throttie
body
and
¡ay
aside
.
(Do
not
disconnect
throttie
cable
or
electrical
harness
connectors
to
throttie
body
.)

2
.
Unbolt
dipstick
tube
bracket
from
intakemanifold
.

3
.
Workíng
under
intake
manifold,
disconnect
electrical
harness
connector
from
¡die
speed
control
valve
.

4
.
Remove
two
bolts
retaining
¡die
speed
control
valve
to
underside
of
intake
manifold
.
Remove
valve
from
intake
manifold
.
Remove
hose
clamp
and
disconnect
hose
.

ECM
PIN
ASSIGNMENTS

mately
one
minute
.

Vacuum
seal

Mounting
bracket

Electrical
connector

0013185

Fig
.
41
.
M52
engine
:
¡die
speed
control
valve
(located
under
intake
manifold)
.

5
.
Installation
ís
reverse
of
removal
.
Use
new
gaskets
when
installing
.

NOTE
-

Poor
driveabilíty
may
be
noticed
atter
installing
a
re-
placement
idle
speed
control
valve
.
After
about
10
min-utes
of
dríving
the
idle
speed
should
return
to
normal
.

ECM
PIN
ASSIGNMENTS

2
.
Remove
twomountingscrews
holding
sensor
to
throttie
housing
.



Engine
control
module
(ECM),
accessing

1
.
Disconnect
negative
(-)
battery
cable
.
Wait
approxi-

CAUTION-

Prior
to
disconnecting
the
battery,
read
the
battery
disconnection
cautions
given
at
the
front
of
this
manual
onpage
vüi
.

2
.
Remove
engine
control
module
(ECM)
compartment
cover
from
right
side
of
engine
compartment
rear
bulk-
head
.
Cover
is
retained
withfour
captíve
screws
.
See
Fig
.
42
.

3
.
Disconnect
control
module
harness
connector
by
re-
leasing
fastener
and
pivoting
connectorup
and
off
ECM
.

4
.
Remove
ECM
from
retaining
brackets
and
pull
ECM
from
its
holder
.

5
.
Installation
is
reverse
of
removal
.

0013ZIM
Fig
.
42
.
Engine
control
module
(ECM)
located
in
compartment
in
right-rearof
engine
compartment
(arrow)
.

NOTE-

Replacement
ECMs
must
be
coded
with
application
in-
formation
(Le
.
engine
code,
transmission
type,
etc
.)
pri-
or
to
installation
.
Consult
an
authorized
BMW
dealer
before
replacing
the
ECM
.

ECM
pin
assignments
are
given
in
Tables
h
through
Table
I.
This
information
can
be
helpful
when
diagnosing
faultsto
or
from
the
ECM
.
If
al¡
inputs
and
wiring
are
OK
butoperational
problems
still
exist,
the
ECM
itself
may
be
faulty
.

Fig
.
43
.
ECM
pin
numbers
as
seen
from
back
of
ECM
connector
.

FUEL
INJECTION



130-
2
7

Generally,
absence
of
voltage
or
continuity
means
there
is
a
wiring
or
connector
problem
.
Test
results
with
incorrect
values
do
notnecessarily
mean
that
a
component
is
faulty
:
Check
for
loose,
broken
or
corroded
connections
and
wiring
before
re-
placing
components
.
If
the
results
are
still
incorrect,
test
the
component
itself
.
For
engine
management
system
electrical
schematics,
see
Electrical
Wiring
Diagrams
.

CAUTION-

Always
waitat
least
40
seconds
after
tuniing
off
the
ignition
before
removing
the
connector
from
the
engine
control
module
(ECM)
.
If
the
connec-
tor
is
removed
before
this
time,
residual
power
in
the
system
relay
may
damage
the
ECM
.

"
Always
connector
disconnect
the
control
module
connector
and
meter
probes
with
the
ignitionoff
.

When
making
checks
at
the
ECM
itself,
a
breakout
box
should
be
used
to
allow
tests
to
be
made
with
the
connector
attached
to
the
ECM
.
This
also
prevents
damage
tothe
small
termínals
in
the
connector
.
As
an
alternative,
theharness
con-
nector
housing
can
be
separated
so
that
electrical
checks
can
be
made
from
the
back
of
the
connector
.
ECM
pin
numbering
is
shown
in
Fig
.
43
.

NOTE
-

On
cars
with
tractioncontrol,
do
not
confuse
the
throttle
position
sensor
on
the
main
throttle
body
with
the
throt-
tle
position
switch
on
the
secondary
throttle
body
.

27
Lb
2L4
LJ
22
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®®®®®®®®®®®®®®®IZA®®®®®®®®®®®®®®®®®

1
>I-
0013211

ECM
PIN
ASSIGNMENTS

2
.
Remove
fuel
tank
filler
cap
.

3
.
Remove
rearseat
cushion
and
pull
back
insulation
mats
to
expose
fuel
tank
access
covers
.
See
Fig
.
2
.

uui3140

Fig
.
2
.



Right
side
fuel
tank
access
cover
under
rear
seat
cushion
.

4
.
Remove
right
and
left
access
covers
to
expose
fuel
hoses
and
electrical
connections
at
tank
.

5
.
Label
fuel
hoses
.
Then
disconnect
hoses
and
harness
connectors
from
fuel
sending
units
and
fuel
pump
.
See
Fig
.
3
.

FUELTANK
AND
FUEL
PUMP



160-
3

NOTE-

"
If
necessary,
push
fuel
level
sender
arm
toward
fuel
pump
assembly
to
facilitate
removal
.

"
BMW
special
tool
no
.
16
1
020
should
beused
tore-
move
and
install
the
threaded
collar
.
Damage
to
thecollar
may
result
if
the
special
tool
is
not
used
.

"
Pump
out
contents
of
each
tanklobe
using
approved
pumpinglextraction
equipment
and
flexible
fuel-grade
hose
.

WARNING
-

Fuel
may
be
spilled
.
Do
not
smoke
or
work
near
heaters
or
other
fire
hazards
.

7
.
Installation
of
sending
units
is
reverse
of
removal,
not-
ing
the
following
:

"
Use
new
sealing
rings
when
installing
pump/sending
unit
assemblies
.
"
Be
sure
that
fuel
line
connections
point
in
same
direc-tion
as
they
carne
out
.
"
Fill
tank
and
check
for
leaks
by
running
engine
.

CA
UTION-

Before
starting
the
engine,
fill
the
fuel
tank
with
at
least
1.5
gallons
(5liters)
of
fuel
.
The
pump
will
be
damaged
if
you
run
it
without
fuel
.

Fuel
tank,
removing
and
installing

1.
Disconnect
negative
(-)cablefrom
battery
:

CAUTION-

Prior
to
disconnectiog
the
battery,
read
the
battery
disconnection
cautions
given
at
the
front
of
this
manual
onpage
viii
.

2
.
Remove
fuel
tank
filler
capand
drain
tank
as
described
earlier
.

3
.
Working
in
left
access
tank
access
hole
(under
rear

seat
cushion),
remove
vent
pipe
fromtank
.

4
.
Working
inside
car,
disconnectparking
brake
cable
ends
from
parking
brake
lever
.
See
340
Brakes
.

5
.
Working
underneath
car,
gently
pry
fuel
lines
away
from
retaining
bracket
in
front
of
tank
.
Remove
clamps
and
disconnect
fuel
hoses
as
shown
in
Fig
.
4
.

6
.
Remove
exhaust
system
and
heat
shield
as
described

ooisiai



in
180
Exhaust
System
.
See
Fig
.
5
.

Fig
.
3
.



Fuel
pump/fuel
level
sender
assembly
in
top
offuel
tank
(right
side
shown)
.
Disconnect
supply
hose
(A),
return
hose
(B)
and



7
.
Remove
driveshaft
.
See
260
Driveshaft
.
harness
connector
(C)
.

8
.
Pull
parking
brake
cables
backward
away
from
bottom
of

6
.
Unscrew
threaded
collars
from
fuel
tank
.
Slowly
with-



fuel
tank,
disengaging
them
from
brackets
as
needed
.

draw
fuel
sender
assemblies
from
tank,allowing
fuel
to
drain
off
.

FUEL
TANKAND
LINES

Fuel
leve¡
senders,
testing



Fuel
leve¡
sender
(right
side)

The
left
and
right
fuelleve¡
sending
units
are
wired
in
series
.



and
fuel
pump,
removing
and
installing

The
fuel
gauge
receives
a
signal
that
is
the
average
of
the
two



1
.
Disconnect
negative
(-)
cable
from
battery
.

input
values
.

1
.
Remove
rear
seat
cushion,
lift
up
insulation
mats,
andremove
both
fuel
tank
access
covers
.

2
.
Disconnect
white
plug
on
each
sending
unit
.
See
Fig
.
6
.

3
.
Check
resistance
value
of
eachsending
unit
.
Values
should
be
the
same
.

5
.
If
valuesare
different,
remove
sending
units
as
described

below,
and
check
resistance
valuésacross
terminals
.
Table
a

lists
resistance
values
for
senders
at
various
float
positions
.

Table
a
.
Fuel
Leve¡
Sender
Resistances

Float
position



Test
result
(ohms)

Right
side
empty



10
ohm
t2

Right
side
full



250
ohm
±
5
Left
side
empty



10
ohm
t
2

Left
side
fui¡



250
ohm
±
5

FUEL
TANK
AND
FUEL
PUMP



160-
5

CAUTION
-

Prior
to
disconnecting
the
battery,
read
the
battery
disconnection
cautionsglven
at
the
front
of
this
manual
onpage
viii
.

2
.
Drain
fuel
from
tank
as
described
earlier
.

WARNING
-

Always
unscrew
the
fuel
tank
cap
to
release
pres-
sure
in
the
tank
before
working
on
the
tank
or
fines
.

3
.
Remove
rear
seat
cushion
and
pull
back
insulation
pad
under
right
side
.

4
.
Remove
screws
holding
rightfuel
tank
accesscover
.

Remove
cover
.

5
.
Label
fuel
hoses
.
Disconnect
hoses
and
harness
con-

nectors
from
fuel
sending
unit
and
fuel
pump
.

6
.
Unscrew
threaded
collar
from
fuel
pumplfuel
leve¡
sender
.
Slowly
withdraw
assembly
from
tank,allowing

fuelto
drain
off
.
See
Fig
.
7
.
0013187
&
0013194

Fig
.
6
.



Fuel
pump/leve¡
sender
terminal
identification
.
Check
resis-
tance
at
terminals
of
white
connectors
(arrows)
.



"
If
necessary,
push
leve¡
sender
arm
toward
fuel
pump

assembly
to
facilitate
removal
.

NOTE
-

BMW
special
tool
no
.
16
1
020
should
beused
to
re-
move
and
install
the
threaded
collar
.
Damage
to
the
collar
may
result
if
the
special
tool
is
not
used

WARNING
-

NOTE-



Fuel
may
be
spilled
.
Do
not
smoke
or
work
near

The
compensating
siphon
pump
(Fig
.
1)
maintains
the



heaters
or
other
fire
hazards
.

fuel
leve¡
between
the
right
and
left
tank
lobes
.
If
the
re-
sistances
are
different
between
the
left
and
right
send-
ers,
remove
the
senders
and
visually
inspect
the
leve)
in



7
.
Using
a
new
sealing
ring,
install
pump
and
sending
each
lobe
.
If
the
leve¡
is
different,
check
the
siphon
com-



unit,
being
sure
that
fuel
line
connections
point
in
same

pensating
pump
.



direction
as
they
carne
out
.

8
.
Reconnect
harnessconnector
and
hoses
.
Fill
tank
and

check
for
leaks
by
running
engine
.
Insta¡¡
access
cover

and
its
mountingscrews
.
Reconnect
negative
(-)
cable

to
battery
.

CAUTION
-

Before
starting
the
engine,
fill
the
fuel
tank
with
at
least
1
.5
gallons
(5liters)
of
fuel
.
The
pump
will
be
damaged
if
you
run
it
without
fuel
.

FUEL
LEVEL
SENDERS

Fig
.
9
.



Fuel
pump
relay
terminal
identification
.

Fuel
Pump
Electrical
Tests

Troubleshooting
of
any
fuel
pump
fault
should
begin
with

checking
the
fuel
pump
fuse
and
the
fuel
pump
relay
.
The
DME
main
relay
should
also
be
checked
.

NOTE-

Special
tools
are
requíred
for
some
of
the
tests
de-
scribed
here
.

Fuel
pump
electrical
circuit,
testing

The
fuel
pump
electrical
circuit
diagram
is
shown
in
Fig
.
10
.

3
.
If
fuel
pump
does
not
run,
disconnect
black
harness

connector
from
tank
sender
unit
.
With
jumper
wire
con-

nectedas
described
in
step
2
above,
check
for
positive

(+)
batteryvoltage
at
harness
connector
terminals
.
See
Fig
.
11
.

FUEL
TANK
AND
FUEL
PUMP



160-
7

From
Main
Relay
(+15
power
with
key
in
run



From
B+juretion
point
orstartposition)
(batteryvoRageatalltirnes)

'
.5
RD/Nrr



1
.5
RD

1
.5
GNNI

From
Engine



2
.5
GNNI
Control
Module



15
2
.5
GNNI

Ground
(below
center
console)

Fig
.
10
.
Fuel
pump
electrical
circuit
.

30

-~
Relay
Fuel
Pump

8~T

I



1

s
ám
61
Front
Power
I



a
1
Distribution
Box
I_
16

WIRING
COLOR
CODE

BK
-
BLACK
BR
-
BROWN
Fuel
Pump



RD



-



RED
(in-tank)
M
YL
YELLOWGN
-
GREENBU
-
BLUE
1
VI
-
VIOLET
GY
-
GREY
WT
-
WHITE
PK
-
PINK

0011946

4
.
If
voltage
and
groundare
present,
fuel
pump
is
proba-
bly
faulty
.
If
there
is
no
voltage,
check
wiring
From
fuel
pump
Reay
and
make
sure
Reay
is
functioning
correctly
.

CAUTION-

Fuseandrelaylocationsmayvary
.
Usecara
when



Fuel
pump
power
consumption,
testing

troubleshooting
the
electrical
system
at
the
fuselrelay
panel
.
To
resolve
problems
in
identify-



NOTE-
ing
a
relay,
see
en
authorízed
BMW
dealer
.



"
To
achieveaccurate
testresults,
fhe
battery
voltage
at
the
connector
should
be
approximately
13
volts
.
1.
Remove
rearseat
cushion,
pull
right
side
insulation
mat



Charge
the
battery
asnecessary
.

back
to
expose
fuel
tank
accesscover
.
Remove
cover



.
q
higher
than
normal
power
consumption
usually
fin-
to
expose
wiring
connections
.



dicates
a
worn
fuel
pump,
which
may
cause
intermit-
tentfuel
starvation
due
lo
pump
overheating
and
2
.
Remove
fuel
pump
relay
and
opérate
fuel
pump
as
de-



seizure
.
The
only
remedy
is
pump
replacement
.
Be
scribed
under
Operating
fuel
pump
for
tests
earlier
.



sure
to
check
that
thereturn
fine
and
the
pump
pickup
Pump
should
run
.
Disconnect
jumper
wire
when
fin-



are
not
obstructed
before
replacing
the
pump
.

ished
.
1
.
Remove
rear
seat
cushion,
pull
right
side
insulation
mal
back
to
expose
fuel
tank
accesscover
.
Remove
cover
to
expose
wiring
connections
.

2
.
Disconnect
(black)
harness
connector
from
fuel
pump
.

3
.
Connect
an
ammeter
and
an
insulated
jumper
wire
be-

tween
terminals
in
connector
and
corresponding
pump

terminals
.
See
Fig
.
12
.

FUEL
PUMP

160-
8



FUEL
TANK
AND
FUEL
PUMP

UU131
tst5

Fig
.
11
.
Voltage
supply
to
fuel
pump
harness
(black)
connector
being
checked
(arrow)
.

00131ts7

Fig
.
12
.
Test
fuel
pump
for
current
draw
by
attadhing
ammeter
andjumper
wire
as
shown
.

CAUTION-

Do
not
allow
the
test
leads
to
short
to
ground
.

NOTE-

See
600
Electrical
System-General
for
information
on
electricaltests
using
a
digital
multimeter
(DMM)
.

4
.
Run
pump
as
described
in
Operating
fuel
pump
for
tests
.

FUEL
PUMP

5
.
Compare
ammeter
reading
with
specification
listed
in

Table
b
.

Maximum
current



5
.0
amps
consumption

FuelDelivery
Tests

Table
b
.
Fuel
Pump
Current

Checking
fuel
delivery
is
a
fundamental
part
of
trouble-

shooting
and
diagnosing
the
DME
system
.
Fuelpressure
di-

rectly
influences
fuel
delivery
.
An
accurate
fuel
pressure

gauge
will
be
needed
to
make
the
tests
.

There
arethree
significant
fuel
delivery
values
to
bemea-

sured
:

"
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,
suchas
clogged
fuel
filter
.

"
Residual
pressure-the
pressure
maintained
in
the

closed
system
after
the
engine
and
fuel
pump
areshut

off
.

Procedures
for
measuring
the
first
two
quantities
arede-

scribed
here
.

Residual
fuel
pressure
is
checked
using
the
procedurede-

tailed
in
130
Fuel
Injection
.

Relieving
fuel
pressure
and
connecting

fuel
pressure
gauge

WARNING
-

"
Gasoline
is
highly
flammable
and
its
vaporsare
explosive
.
Do
not
smoke
or
work
ona
car
near
heaters
or
other
fire
hazards
when
diagnosing
and
repairing
fuel
system
problems
.
Have
a
fire
extinguisher
available
in
case
of
an
emergency
.

"
When
working
onan
open
fuel
system,
wear
suit-
able
hand
protection
.
Prolonged
contact
with
fuel
can
cause
iflnesses
and
skin
disorders
.

CA
UTION-

Cleanliness
is
essential
when
working
withfuel
circuit
components
.
Thoroughly
clean
the
unionsbefore
disconnecting
fuel
fines

To
prevent
fuel
from
spraying
on
a
hotengine,
system
fuel

pressure
should
be
relieved
before
disconnecting
fuel
lines
.

One
method
is
to
tightly
wrap
a
shop
towel
around
a
fuel
line
fit-
ting
and
loosen
or
disconnect
the
fitting
.

Measuring
fuel
pressure
requires
special
tools
.
Earlier
cars
use
pressure
hose
with
clamps
for
fuel
delivery
.
These
can
be
attached
to
a
fuel
pressure
gauge
below
the
intake
manifold
.