1992 BMW 318i Engine management wiring

GENERAL
.
.....
.
.
.
.
.
.
.
...
.
.
.
.
.
.
.
.
.
...
100-1

Cylinder
Block
and
Crankshaft
.
.
.
.
.
.
.
.
.
...
100-1

Connecting
Rods
and
Pistons
.
.
.
.
.
.
.
.
.
.
.
.
.
100-1

Cylinder
Head
and
Valvetrain
.
.
.
.
.
.
.
.
.
.
.
.
.
100-2

VANOS
(Variable
Valve
Timing)
.
.
.
.
.
.
.
.
...
100-2

DISA
(Dual
Resonance
Intake
System)
.
.
.
.
.
100-3

Engine
Management
System
.
.
.
.
.
.
.
.
.
.
.
.
.
100-3

Ignition
......
.
.
.
.........
.
.
.
.
.
.
.
.
.
.
.
.
100-5

Fuel
Delivery
..
.
.
.
.....
.
...
.
.
.
.
.
.
.
.
.
.
.
.
100-5

Cooling
System
.
...........
.
.
.
.
.
.....
.
.
100-5

Lubrication
System
.........
.
.
.
.
.
.
.
.
.
.
.
.
100-5

MECHANICALTROUBLESHOOTING
.
.
.
.
100-5

Warnings
and
Cautions
..
.
...
.
.
.
.
.
.
.
.
.
.
.
.
100-5

Cylinder
compression,
checking
.
.
.
.
.
.
.
.
.
.
.
100-6

EngineMechanical
Troubleshooting
Table
.
.
.
100-7

DRIVEABILITY
TROUBLESHOOTING
...
100-8

GENERAL

There
are
various
engíne
configurations
used
in
the
1992-

1998
E36
cars
.
See
Table
a
.

On
both
four-
and
6-cylinder
engines,
the
cylinder
block
is

cast
¡ron
with
integral
cyiinders
.
The
cyiinders
are
exposed
on

all
sides
to
circulating
coolant
.

The
fully
counterweighted
crankshaft
rotates
in
replaceable

split-shell
main
bearings
.
Oiiways
drilled
into
the
crankshaft
pro-

vide
bearing
lubrication
.
O¡I
seals
pressed
into
alloy
sea¡
hous-

ings
are
installedat
both
ends
of
the
crankshaft
.

100
Engine-General

Tablea
.
Engine
Specifications

ENGINE-GENERAL
100-1

On-Board
Diagnostics
(OBD)
...
.
.
.
.
.
.
.
.
.
.
.
100-8

Basic
Requirements
....
.
.
.
...
.
.
.
.
.
....
.100-11

Preventive
Maintenance
......
.
.
.
.
.
.....
100-11

Basic
Engine
Settings
..
.
.....
.
.
.
.
.
.....
100-11

Oxygen
Sensors
.
.
.
...
.
.
.
...
.
.
.
.
.
....
.100-11

Air
Flow
Measurement
and
Vacuum
Leaks
.
.100-12

Battery
Voltage
.
.
...........
.
.
.
.
.
.....
100-12

Wiring
and
Harness
Connections
.
.
.
.
.....
100-13

Ground
Connections
...
.
.....
.
.
.
.
.
.....
100-13

Fue¡
Supply
....
.
...........
.
.
..
.....
.100-14

TABLES

a
.
Engine
Specifications
...
...
...........
.
..
..
.100-1

b
.
Engine
Management
Systems
..
..
...........
..
100-5

c
.
Engine
Mechanical
Troubleshooting
..........
.
.
100-8

d
.
OBD
1
Fault
(Blink)
Codes
(1992-1995
models
only)
.
...
..
..
..........
..
.100-9
e
.
Engine
Driveability
Troubleshooting
...........
.100-15
Model



Engine
code



No
.
of



Dispiacement



Compression



Horsepower
cyiinders



liters
(cu
.
in
.)



ratio



SAE
net
@
rpm

318i/is/¡C
1992-1995



M42



4



1
.8
(109
.6)



10
.0
:1



100
@
6000
1996-1998



M44



4



1
.9
(115
.6)



~
10
.0
:1



103
@
6000

323ís/iC
1998



M52



6



2
.5
(152
.2)



10
.5
:1



168
@
5,500

325i/is/iC
1992-1995



M50



6



2
.5
(152
.2)



10
.0
:1



110
@
5,900

328i/is/iC
1996-1998



M52



6



2
.8
(170
.4)



10
.2
:1



190
@
5,300

M3
1995



S50US



6



3
.0
(182
.5)



10
.5:1



240
@
6,000
1996-1998



S52US



6



3
.2
(192
.3)



10
.5:1



240
@
6,000
Cylinder
Block
and
Crankshaft



Connecting
Rods
and
Pistons

The
forged
connecting
rods
use
replaceable
split-shell

bearings
at
the
crankshaft
endand
solid
bushings
at
the
pis-

ton
pin
end
.
The
pistonsare
of
the
three-ring
typewith
two
up-
per
compression
rings
and
a
lowerone-piece
o¡i
scraper
ring
.

Fui¡-floating
piston
pins
are
retained
with
circlips
.

GENERAL

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

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

120-
6



IGNITION
SYSTEM

Crankshaft
position/rpm
sensor,

testing
and
replacing
(front
mounted)

1
.
Disconnect
sensor
harness
connector
.

2
.
Using
a
digital
multimeter,
check
resistance
between
terminals
1
and
2
in
connector
.
See
Fig
.
10
.

n1
n2n3

Fig
.
10
.
Crankshaft
position/rpm
sensorconnector
.

Crankshaft
positionlrpm
sensor
specifications

"
Coil
resistance
(approx
.)
terminais
1
and
2
....
.
..
...
....
1280
±
10%
ohms

"
Air
gap
(sensor
distance
from
toothed
wheel)
..
.
.
........
.1
.0
±
0
.3
mm
(0
.04
±
0
.01
in
.)

3
.
If
the
resistance
is
not
correct,
the
sensor
is
faulty
and
should
be
replaced
.

NOTE
-

When
installing
the
new
sensor,
be
sure
thewiring
Is
rerouted
in
the
same
orientation
.
Secure
the
sensor
us-
ing
new
wire
ties
.

Tightening
Torque

"
Crankshaft
position/rpm
sensor
to
mounting
bracket
.........
.
.
5
t
1
Nm
(62
t
9
in-lb)

Crankshaft
position/rpm
sensor,



4
.
Installation
is
reverse
of
removal
.
Use
a
new
O-ring
replacing
(rear
mounted)



when
installing
sensor
.
Be
sure
wiring
is
rerouted
in
same
orientation
.
1
.
Disconnect
sensor
harness
connector
.

6502AGN56

2
.
Locatesensor
on
rear
left
sideof
cylinder
block
.
Re-
move
sensormounting
bolt
and
remove
sensorfrom
cylinder
block
.

IGNITION
SYSTEM
SERVICE

3
.
Installation
is
reverse
of
removal
.
Use
a
new
O-ring

when
installing
sensor
.
Be
sure
wiring
is
rerouted
in
same
orientation
.
Secure
sensor
using
new
wire
ties
.

NOTE-

It
may
be
easier
to
remove
the
sensor
working
from
the
underside
of
the
vehicle
.

Camshaft
Position
(CMP)
Sensor

The
camshaft
position
(CMP)
sensor
is
usedby
the
engine
management
system
for
sequential
fuel
injection
and
knock
control
.

Camshaft
position
(CMP)
sensor,

replacing
(4-cylinder
engine)

1
.
Remove
CMP
sensorfromtop
timing
cover,
just
above
coolantthermostat
housing
.
See
Fig
.
11
.

Fig
.
11
.
Camshaft
position
sensor
mounting
bolt
(arrow)
.
M42
engine
shown
.

2
.
On
M42
engines
to
9/93
:
Disconnect
CMP
harness
plug
just
above
oil
filter
housing
.

3
.
On
M42
from9/93
and
all
M44
engines
:
Remove
upper
intake
manifold
as
described
in
113
Cylinder
Head
Re-
moval
and
Installation
.
Then
unplug
CMP
sensor
har-
ness
connector
below
manifold
.

Camshaft
position
(CMP)
sensor,

replacing
(6-cylinder
engine)

1
.
Remove
plastic
cover
from
above
fuel
injectors
.

2
.
Disconnect
harness
connector
from
VANOS
solenoid

and
unscrew
solenoid
from
VANOS
control
unit
.
Re-



"
Clean
contactsurface
on
engine
block
before
fnstall

move
oil
supply
line
from
VANOS
control
unit
.
See
117



ing
knock
sensors
.

Camshaft
Timing
Chain
.

3
.
Remove
camshaft
position
(CMP)
sensor
from
left
frontof

cylinder
head,
next
to
top
of
oil
filter
housing
.



"
Knock
sensor
to
cylinder
block
....
20
Nm
(15
ft
.
lbs
.)

4
.
Disconnect
CMP
sensor
harnessfrom
under
intake

manifold
.

5
.
Installation
is
reverse
of
removal
.
Use
a
new
O-ring

when
installing
sensor
.
Be
sure
wiring
is
rerouted
in

same
orientation
.

Tightening
Torques

"
CMP
sensor
to
cylinder
head
....
.
.
..
5
Nm
(3
.5
ft-Ib)

"
VANOS
oil
supply
pipe
to

VANOS
control
unit
...........
.
..
32
Nm
(24
ft-Ib)

"
VANOS
solenoid
to
VANOS

control
unit
...
.
.................
30
Nm
(22
ft-Ib)

Knock
sensors,
replacing

Knock
sensors
are
usedon
engines
with
Bosch
DME
M1
.7,

Bosch
DME
M3
.3
.1,
Bosch
DME
M5
.2,
and
Siemens
MS
41
.1

engine
management
systems
.
The
knocksensors
are
bolted
to
the
left
sideof
the
cylinder
block
and
monitor
the
combus-

tion
chamber
for
engine-damaging
knock
.
If
engine
knock
is

detected,
the
ignition
point
is
retarded
accordingly
via
the
en-

gine
control
module
.

CA
UTION-

"
Label
knock
sensorharness
connectors
before

disconnecting
them
.
The
connectors
must
not
be

interchanged
.
Engine
damage
may
result
if
the
sensors
are
monitoring
the
wrong
cytinders
.

"
Note
the
installed
angle
of
the
knock
sensoron
the

block
before
removing
it
.
Reinstall
the
sensor
in

the
same
position
.
Be
sure
to
usea
torque
wrench

when
tightening
the
sensormounting
bola

NOTE
-

"
On
M52
engines,
a
single
harness
connects
the
twosensors
to
the
main
harness
connector
.
The
shorter
cable
lead
fs
for
the
knock
sensor
for
cytinders
4,
5,
and
6
.

Tightening
Torque

IGNITION
SYSTEM



120-
7

0012730

Fig
.
12
.
Knock
sensor
mounting
bolt
on
front
left
side
of
cylinder

block
.

NOTE-

Knock
sensor
function
Is
monitoredby
the
On-Board
Diagnostic
system
.
If
a
knock
sensor
is
detected
to
be
faulty,
an
appropriatediagnostic
trouble
code
(DTC)
may
be
stored
in
memory
.
See
100
Engine-General
for
information
on
retrieving
DTCs
.

On
6-cylinder
engines,
the
knock
sensors
are
accessible
af-
ter
removing
the
intake
manifold
.
On
4-cylinder
engines,
the

upper
section
of
the
intake
manifold
should
be
removed
to
ac-

cess
the
sensors
.
See
Fig
.
12
.
NOTE-

Intakemanifold
removal
and
installation
procedures
are



"
Cylinder
no
.
1is
at
the
front
of
the
engine
.

covered
in
113
Cylinder
HeadRemoval
and
Installation
.

Ignition
Firing
Order

Ignition
Firing
Order

"
4-cylinder
engines
.....
..
...
.
..........
.1-3-4-2

"
6-cylinder
engines
...........
..
.
.
..
..
1-5-3-6-2-4

IGNITION
SYSTEM
SCHEMATICS

Fig
.
13
through
Fig
.
17
show
ignition
system
schematics

usedon
the
enginescoveredby
this
manual
.

IGNITION
SYSTEM
SCHEMATICS

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
.

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

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
.