running light BMW 318i 1996 E36 User Guide

121-2



BATTERY,
STARTER,
ALTERNATOR

CHARGING
SYSTEM
TROUBLESHOOTING



Static
currentdraw,
checking

Charging
system
diagnostics
requires
special
test
equip-

ment
.
If
the
test
equipment
is
not
available,
charging
system

fault
diagnosis
can
be
performedby
an
authorized
BMW
deal-

eror
other
qualified
repair
shop
.
A
general
troubleshooting

guide
is
given
in
Table
a
.

Charging
System
Quick-Check

As
a
quick-check,
use
a
digital
multimeter
lo
measure
volt-



2
.
Disconnect
battery
negative
(-)
cable
.

age
across
the
battery
terminals
with
the
key
off
and
then

again
with
the
engine
running
.
The
battery
voltage
should
be



CAUTION-
about12
.6
volts
with
key
off
and
approximately
14
.0
volts
with



Prior
to
disconnecting
the
battery,
read
the
battery
the
engine
running
.
If
the
voltage
does
not
increase
when
the



disconnection
cautions
given
at
the
front
of
this
engine
is
running,there
is
a
fault
in
the
charging
system
.



manual
onpaga
viii
.

NOTE
-

The
regulated
voltage
(engine
running)
should
be
be-
tween
13
.5
and
14
.5,
depending
on
temperatura
and
operating
conditions
.
If
the
voltage
is
higher
than
14
.8,
the
voltage
regulator
is
most
Mely
faulty
.

Check
for
clean
and
tight
battery
cables
.
Check
the
ground

cable
running
from
the
negative
(-)
battery
terminal
lo
the

chassis
and
the
ground
cable
running
from
the
engine
lo
the

chassis
.
Check
the
alternator
drive
belt
condition
and
tension
.

If
the
battery
discharges
over
time,
there
may
be
a
constant

drain
or
current
draw
on
the
battery
.
A
small
static
drain
on
the

battery
is
normal,
but
a
largedrain
will
cause
the
battery
lo

quickly
discharge
.
Make
a
static
current
draw
test
asthe
first

step
when
experiencing
battery
discharge
.

1
.
Make
sure
ignition
and
al¡
electrical
accessories
are

switched
off
.

3
.
Connect
a
digital
ammeter
between
negative
battery

post
and
negative
battery
cable
lo
measure
current
.

See
Fig
.
1
.
Wait
at
least
one
minuta
lo
get
an
accurate

reading
.

A
range
of
about
0
lo
100
milliamps
is
normal,
dependingon

the
number
of
accessories
that
need
constant
power
.
A
current

of
400
milliamps
(0.4
amp)
or
more
may
indicate
a
problem
.

Table
a
.
Battery,
Starter
and
Charging
System
Troubleshooting

Symptom



1



Probable
Cause



1



Correctiva
Action

1
.
Engine
cranks
slowlyor
not



a
.
Battery
cables
loose,
dirty
orcor-



a
.
Clean
or
replace
cables
.
See020
Maintenance
Program
.
a
tall,
solenoíd
clicks
when



roded
.
starter
is
operated
.



b
.
Battery
discharged
.



b
.
Charge
battery,
test
and
replace
if
necessary
.
c
.
Body
ground
straploose,
dirty
or



c
.
Inspect
ground
strap,
clean,
tighten
or
replace
if
necessary
.
corroded
.
d
.
Poor
connection
at
starter
motor



d
.
Check
connections,
test
for
voltage
at
starter
.
Test
for
voltage
at
terminal
30
.



neutral
safety
or
clutch
interlock
switch
.
e
.
Starter
motor
or
solenoid
faulty
.



e
.
Test
starter
.

2
.
Battery
will
not
stay



a
.
Short
circuit
draining
the
battery
.



a
.
Test
for
excessive
current
drainwith
everything
electrical
in
the
charged
more
than
a
few



vehicle
off
.
days
.



b
.
Short
driving
trips
and
high
elec-



b
.
Evaluate
driving
style
.
Where
possible,
reduce
electrical
con
trical
drain
on
charging
system



sumption
when
making
short
trips
.
does
not
allow
battery
to
re-
charge
.
c
.
Drive
belt(s)
worn
or
damaged
.



c
.
Inspect
or
replace
multi-ribbed
belt(s)
.
See
020
Maintenance
Program
.
d
.
Battery
faulty
.



d
.
Test
battery
and
replace
íf
necessary
.
e
.
Battery
cables
loose,
dirty
orcor-



e
.
Clean
or
replace
cables
.
See
020
Maintenance
Program
.
rodad
.
f
.
Alternatoror
voltage
regulator



f
.
Test
alternator
and
voltage
regulator
.
faulty
.

3
.
Battery
losing
water
.



1
a
.
Battery
overcharging
.



1
a
.
Test
voltage
regulator
for
proper
operation
.

4
.
Lights
dim,
light
intensity



a
.
Drive
belt(s)
worn
or
damaged
.



a
.
Inspect
or
replace
multi-ribbed
belt(s)
.
See
020
Maintenance
varies
with
engine
speed
.



Program
.
b
.
Alternatoror
voltage
regulator



b
.
Test
alternator
and
voltage
regulator
.
faulty
.
c
.
Body
ground
straps
loose,
dirty
or



c
.
Inspect
ground
straps,
clean,
tighten
or
replace
as
necessary
.
corroded
.

CHARGING
SYSTEM
TROUBLESHOOTING

Fig
.1.



Electrical
system
static
current
draw
being
measured
.

To
determine
the
circuit
or
component
causing
the
problem,

remove
one
Puse
at
a
time
until
the
current
drops
to
a
normal
range
.

BATTERY
SERVICE

The
E36
uses
a
six-cell,
12-volt
leadacid
battery
mounted

in
the
luggage
compartment
.
See
Fig
.
2
.

NOTE-

E36
convertible
models
require
a
specialbattery
which
is
designed
for
constant
vibratfon
.
A
battery
not
de-signed
for
this
will
fail
much
earlier
.

Battery
capacity
is
determined
by
the
amount
of
current

needed
tostart
the
vehicle,
and
by
the
amount
of
current
con-
sumed
by
the
electrical
system
.

BMW
batteries
are
rated
by
ampere/hours
(Ah)
and
cold

cranking
amps
(CCA)
rating
.
The
Ah
rating
is
determined
by

the
average
amount
of
current
the
battery
can
deliver
over
time
without
dropping
below
a
specified
voltage
.
The
CCA
is

determined
by
the
battery's
ability
to
deliver
starting
current
at

0°
F
(-18°
C)
without
dropping
below
a
specified
voltage
.

Battery
Testing

noN~A

B9517

Battery
testing
determines
the
state
of
battery
charge
.
On

conventional
or
low-maintenance
batteries
the
most
common

method
of
testing
the
battery
is
that
of
checking
the
specific

gravity
of
the
electrolyte
using
a
hydrometer
.
Before
testing

the
battery,
check
that
the
cables
are
tight
and
free
of
corro-

sion
.
See
Fig
.
2
.

Hydrometer
Testing

The
hydrometer
consists
of
a
glass
cylinder
with
a
freely

moving
float
inside
.
When
electrolyte
is
drawn
into
the
cylin-

der,
the
levelto
which
the
float
sinks
indicates
the
specific

BATTERY,
STARTER,
ALTERNATOR



121-
3

Fig
.
2
.



Battery
in
right
sideof
luggage
compartment
.

gravity
of
the
electrolyte
.
The
more
dense
the
concentration
of
sulfuric
acid
in
the
electrolyte,
the
less
the
float
will
sink,
result-

ing
in
a
higher
reading
and
indicating
a
higher
state
of
charge)
.

NOTE-

Electrolyte
temperature
affects
hydrometer
reading
.
Check
the
electrolyte
temperaturewith
a
thermometer
.
Add
0
.004
to
the
hydrometer
reading
for
every
10°F
(6°C)
that
the
electrolyte
is
above
80°F
(27°C)
.
Sub-
tract
0
.004
from
the
reading
for
every
10°F
(6°C)
that
the
electrolyte
is
below
80°F
(27°C)
.

Before
checking
the
specificgravity
of
a
battery,
load
the
battery
with
15
amperes
for
one
minute
.
lf
the
battery
is
in-

stalled
in
the
vehicle,
this
can
be
done
by
turning
on
the
head-

lights
without
the
engine
running
.
Table
b
lists
the
percentage

of
charge
based
on
specific
gravity
values
.

Table
b
.
Specific
Gravity
of
Battery
Electrolyteat

80
°
F
(27°C)

Specific
gravity



1



Stateof
charge

1
.265



Fully
charged
1
.225



75%
charged
1
.190



50%
charged
1
.155



25%
charged
1
.120



Fully
discharged

The
battery
isin
satisfactory
condition
if
theaverage
specif-

ic
gravity
of
the
six
cells
is
at
least
1
.225
.
If
the
specific
gravity

is
above
this
leve¡,
butthe
battery
lacks
power
for
starting,
de-

termine
the
battery's
senrice
condition
with
a
load
voltage
test,

as
described
below
.
If
the
average
specific
gravity
of
the
six

cells
is
below
1
.225,
remove
the
battery
from
the
luggage

compartment
and
recharge
.
If,
after
recharging,
the
specific
gravity
varies
by
more
than
0
.005
between
any
two
celis,
re-

place
the
battery
.

CHARGING
SYSTEM
TROUBLESHOOTING

121-
4



BATTERY,
STARTER,
ALTERNATOR

BatteryOpen-Circuit
Voltage
Test



Battery
Charging

Before
making
the
test,
load
the
battery
with
15
amperes
for



Discharged
batteries
can
be
recharged
using
a
battery

one
minute
with
a
batteryload-tester
or
turn
on
the
headlights



charger
.
The
battery
should
be
removed
from
the
luggage

for
about
one
minute
without
the
engine
running
.Then
discon-



compartment
during
charging
.

nect
the
battery
negative
(-)
cable
and
connect
a
digital
volt-

meter
acrossthe
battery
terminals
.
Open-circuit
voltage



Prolonged
charging
causes
electrolyte
evaporation
to
a
lev

levels
are
given
in
Table
c
.



el
that
can
damage
the
battery
.
Itis
bestto
use
a
low-current

charger
(6
amperes
or
less)
to
prevent
battery
damage

If
the
open-circuit
voltage
ís
OK
butthe
battery
still
lacks



caused
by
overheating
.

power
for
starting,
make
a
load
voltage
test
.
If
the
open-circuit

voltage
is
below
12
.4
volts,
recharge
the
battery
and
retest
.



WARNING
-

Hydrogen
gas
given
off
by
the
battery
duringcharg-

Table
c
.
Open-Circuit
Voltage
and
Battery
Charge



ing
is
explosive
.
Do
not
smoke
.
Keep
open
llames

away
from
the
top
of
the
battery,
and
prevent
elec
Open-circuit
voltage



State
of
charge



trical
sparks
by
turning
offthe
battery
charger
be-

12
.6
V
or
more



Fully
charged



fore
connecting
or
disconnecting
it
.

12
.4
V



1



75%
charged

12
.2
V



50%
charged



CAUTION-

12
.0
V



25%
charged



"
Battery
electrolyte
(sulfuric
acid)
can
damage
the
car
.
If
electrolyte
isspilled,
clean
the
area
11
.7
V
or
less



Fully
discharged



with
a
solution
of
baking
soda
and
water
.

Battery
Load
Voltage
Test

A
battery
load
tester
is
required
for
a
load
voltage
test
.
The



-
Always
disconnect
both
battery
cables
and
re-

test
is
made
by
applying
a
high
resistive
load
to
the
battery
ter-



move
battery
from
vehicle
during
battery
charg-
ing
.
Do
not
exceed
16
.5volts
at
the
battery
.
minals
and
then
measuring
battery
voltage
.
The
battery
should

be
fully
charged
for
the
most
accurate
results
.
The
battery
ca-

bles
mustbe
disconnected
before
making
the
test
.
If
the
volt-



ALTERNATOR
$ERVICE
age
is
below
that
listed
in
Table
d,
the
battery
should
be

replaced
.

WARNING
-

Always
wear
protective
goggles
and
clothing
when
performing
aload
test
.

Table
d
.
Battery
Load
Test-Minimum
Voltage

(apply
200
amp
load
for
15
seconds)

Ambient
temperature



Voltage

80°F
(27°C)



9
.6
V

60°F
(16°C)



9
.5
V

40°F
(4°C)



9
.3
V

20°F
(-7°C)



8
.9
V

0°F
(-18°C)



8
.5
V

ALTERNATOR
SERVICE

"
Always
allow
a
frozen
battery
to
thaw
before
at-
tempting
to
recharge
it
.

Before
checking
the
alternator
and
regulator,
make
sure
the

battery
is
fully
charged
and
capable
of
holding
acharge
.
Check
that
the
battery
terminals
are
clean
and
tight
and
the
al-

ternator
drive
belt
is
properly
tensioned
and
not
severely

worn
.

Charging
system,
checking

CAUTION-

Do
not
disconnect
the
battery
while
the
engine
is
running,
.
Damage
to
the
alternator
andlorengine
electronic
systems
may
result
.

1.
Turn
ignition
key
on
.
Check
that
the
chargewarning

lamp
comes
on
.

NOTE-

If
the
warning
light
does
not
come
on,
repair
any
wiring
or
bulb
faults
before
continuing
to
check
the
charging
system
.

2
.
Remove
cooling
duct
or
terminal
cover
from
rear
of
al-



2
.
Remove
air
cleaner
upper
section
with
mass
air
flow
ternator
.



sensor
.

3
.
Check
for
battery
voltage
between
ground
and
terminal



3
.
Remove
terminal
cover
from
rear
of
alternator
.
Discon
B+
at
back
of
alternator
.
Then
turn
ignition
on
and



nect
wiring
.
check
for
battery
voltage
between
terminal
D+
and
ground
.
See
Fig
.
3
.
lf
voltage
is
not
present
at
either



4
.
Remove
drive
belt
from
alternator
pulley
.
See
020
point,
check
wiring
for
faults
.



Maintenance
program
.

001
¡987
Fig
.
3
.



Terminal
B+
is
supplied
battery
voltage
directly
from
the
bat-
tery
.
Terminal
D+
is
supplied
battery
voltage
via
the
charge
warning
bulb
when
thekey
is
on
or
the
engine
is
running
.

4
.
lf
no
faults
are
foundup
to
thispoint,test
alternator
out-

put
using
a
load
tester
.

5
.
If
a
load
tester
is
not
available,
a
crude
output
test
can
be
done
by
running
engine
at
about
2000
rpmand
turn-
ing
on
electrical
loads
(fans,
lights
and
rear
window
de-
froster,
wipers)
.
With
al¡
accessories
on,
battery
voltage
should
be
above
12
.0
VDC
.

A
replacement
alternator
should
have
the
same
rating
as
the
original
.
Alternator
manufacturer
and
ampere
rating
are
normally
marked
on
the
alternator
housing
.
1
.
Disconnect
negative
(-)
battery
cable
.

CAUTION-

Prior
to
disconnecting
the
battery,
read
the
battery
disconnection
cautions
given
at
the
front
of
this
manual
on
page
vi¡¡
.

BATTERY,
STARTER,
ALTERNATOR



121-
5

6
.
Remove
upper
and
lower
mounting
bolts
and
lift
out
al-
ternator
.
See
Fig
.
4
.

NOTE
-

If
reusing
drive
belt,
mark
direction
of
rotation
on
belt
before
removing
.

5
.
On
M44
engine
with
hydraulic
belt
tensioner
:
Remove
tensioner
idler
pulley
(upper
roller)
from
alternator

bracket
.

Fig
.
4
.



Alternator
mounting
bolts
(arrows)
.

O



u
J
S
v~~

U

I



1
i
n
-12
.22

Alternator,
removing
and
installing



7
.
Installation
is
reverse
of
removal
.
Install
drive
belt
as

(4-cylinder
engine)



described
in
020
Maintenance
Program
.

Tightening
Torques

"
D+
vire
to
alternator
(M6
nut)
.
...
.
.
.
7
Nm
(53
in-lb)

"
B+
wire
to
alternator
(M8
nut)
..
.
.
.
.
.
13
Nm
(10
ft-Ib)

"
Pulley
to
alternator
(M16
nut)
...
..
..
60
Nm
(44
ft-Ib)

ALTERNATOR
SERVICE

130-
6



FUEL
INJECTION

Warnings
and
Cautions

For
personal
safety,
as
well
as
the
protection
of
sensitive

electronic
components,
the
following
warnings
and
cautions

should
be
adhered
to
when
working
on
the
engine
manage-

ment
system
.

GENERAL
WARNING
-

"
The
ignition
system
produces
high
voltages
that

can
be
fatal
.
Avoid
contact
with
exposed
termi-

nals
.
Use
extreme
caution
when
working
onacar
with
the
ignition
switched
on
or
the
engine
run-
ning
.

"
Do
not
touch
or
disconnect
any
high
voltage
ca-

bles
from
the
coils
or
spark
plugs
while
the
engine

is
running
or
beingcranked
by
the
starter
.

"
Connect
and
disconnect
the
DME
system
wiring
and
test
equipment
leads
only
when
the
ignition
is
switched
off
.

"
Gasoline
is
highly
flammable
and
fts
vaporsare

explosive
.
Do
not
smoke
or
work
on
a
car
near
heaters
or
other
fire
hazards
when
diagnosing
and
repalring
fuel
system
problems
.
Have
a
tire
extinguisher
avaílable
in
case
of
an
emergency
.

"
When
working
onan
open
fuel
system,
wear
suit-
able
hand
protection,
asprolonged
contact
wfth
fuel
can
cause
illnesses
and
skin
disorders
.

"
Renew
fuel
system
hoses,
clamps
and
O-rings
any
timethey
are
removed
.

"
Before
makingany
electrical
tests
that
require
the
engine
to
be
cranked
using
the
starter,
disable
the
ignition
system
as
described
in
120
Ignition
System
.

CAUTION-

"
Prior
to
disconnecting
the
battery,
read
the
bat-
tery
disconnectinn
cautions
given
at
the
front
of
this
manual
onpage
vifi
.

"
Do
not
connect
any
test
equipment
that
delivers

a
12-volt
power
supply
to
terminal
15
(+)
of
the
ig-

nitioncoil
.
The
current
flow
may
damage
the

ECM
.
In
general,
connect
test
equipment
only
as

speclfied
by
BMW,
this
manual,
or
the
equipment

maker
.

"
Only
use
a
digital
multlmeter
for
electrical
test
.

"
Only
use
an
LED
test
light
for
quick
tests
.

"
Disconnecting
the
battery
may
erase
fault

code(s)
stored
in
memory
.
Check
for
fault
codes

prior
to
disconnecting
the
battery
cables
.
ff
the

Check
Engine
light
ís
illuminated,
see100En-
gine-General
for
DME
fault
code
information
.
ff
any
other
system
faults
have
been
detected
(indi-
catedbyan
illuminated
warning
light),
see
an
au-
thorized
BMW
dealer
.
Additional
systems
with
self-diagnostic
capabilities
include,
ABS
(Anti-
lock
brakes),
SRS
(Airbags),
EML
and
ASC+T
and
AST
(Traction
Control)
.

"
Do
not
run
the
engine
wfth
any
of
the
spark
plug
wires
dlsconnected
.
Catalytic
converter
damage
may
result
.

"
Always
waitat
least
40
seconds
afterturning
off
the
ignition
before
removing
the
engine
control
module
(ECM)
connector
.
ff
the
connector
isre-
moved
before
this
time,
residual
power
in
the
sys-
tem
relay
may
damage
the
control
module
.

"
Cleanliness
is
essential
when
working
onan
open
fuel
system
.
Thoroughly
clean
fuel
line
con-
nections
and
surroundlng
areas
before
loosen-
ing
.
Avoid
moving
the
car
.
Only
fnstall
cleanparts
.

"
Fuel
system
cleaners
and
other
chemical
addi-
tives
other
than
those
specifically
recommended
by
BMW
may
damage
the
catalytic
converter,
the
oxygensensor
or
other
fuel
supply
components
.

3
.
Observe
fuel
pressure
gauge
after
20
minutes
.
The

pressure
shouldnot
drop
off
more
than
0
.5
bar
from

system
pressure
listed
in
Tablec
.

4
.
When
finished
testing,
disconnect
pressure
gauge
and
reconnect
fuel
line
.

If
the
fuel
system
does
not
maintain
pressure,
check
visual-
¡y
for
leaks
in
fuel
lines
orat
unions
.
Leaks
can
also
be
due
to
a
leaking
injector
or
a
faulty
fuel
pump
check
valve
.
Check
the

pump
check
valve
by
repeating
the
test,
butbefore
turning
the

fuel
pump
off,
pinch
off
theretum
line
at
the
fuel
rail
.
If
the

pressure
is
now
maintained,
the
fault
is
most
likely
the
fuel

pump
check
valva
.

Tabla
c
.
Fuel
Pressure
Specifications

Engine



1
Fuel
pressure

4-cytinder



1
3
.0
t
0
.2
bar
(43
.5
t
2
.9psi)

6-cytinder
M50/S50US
engine



3
.0
t
0
.2
bar
(43
.5
±2
.9psi)
M52/S52US
engine



3
.5
f
0
.2
bar
(51
t
2.9psi)

Fuel
pressure
regulator
response

to
engine
load,
testing

1
.
With
fuel
pressure
gauge
connected,
reinstallfuel

pump
relay
.
Start
engine
and
allow
it
to
idle
.

NOTE-

The
fuel
pressure
should
be
lower
by0
.4-0.7
bar
from
the
specifications
listed
in
Table
c
.
Engine
vacuum
act-
ing
on
the
fuel
pressure
regulator
diaphragm
reduces
the
fuel
pressure
.

2
.
With
engine
idling,
remove
vacuum
hose
from
regula-

tor
.
Pressure
should
increase
.

3
.
Reconnecthose
and
check
that
pressure
decreases
.

4
.
When
finished
testing,
disconnect
pressure
gauge
and

reconnect
fuelline
.
Tighten
hose
clamp
.



0013190

Fig
.
13
.
For
electrical
tests,
4-cytinder
fuel
injector
harnessduct
can
be

If
fuel
pressure
does
not
drop
with
the
vacuum
hose
con-



accessed
between
intake
manifold
and
cytinder
head
cover
.

nected
and
no
faulty
are
found
with
fuel
the
pressure
regulator

vacuum
hose,
the
fuel
pressure
regulator
is
faulty
.



1
.
Check
that
ECM
signal
is
present
atinjector
connector
.

NOTE-

A
cracked
or
leaktng
pressure-regulator
vacuum
hose

may
cause
en
erratic
tdle
.

FUEL
INJECTION



130-
11

Fuel
rail
and
injectors,
checking

The
fuel
injectors
are
switched
on
and
off
(opened
and
closed)
by
the
ECM
.
The
injectors
are
connected
to
a
com-
mon
fuel
supply,
callad
the
fuel
rail
.

The
fuel
injectors
are
removed
by
first
removing
the
com-
plete
fuel
rail
assembly
and
then
unclipping
the
injectors
from
the
fuel
rail
.

CA
UTION-

Use
only
a
digital
multimeter
or
an
LED
injector
tester
when
testing
injectors
or
wiring
.
Use
of
ananalog
VOM
or
incandescent
testlight
may
dam-
age
the
engine
control
module
.

NOTE-

"
On
4-cytindercars
pry
up
the
injector
wiring
duct
and
then
pry
off
the
cover
.
See
Fig
.
13
.

"
On
6-cytinder
cars
it
is
necessary
to
remove
the
top
engine
cover(s)
to
access
the
fuel
rail
and
injectors
.

"
Back
probe
injector
harness
connector
using
digital

voltmeter
.
See
Fig
.
14
.

"
Operate
starter
or
run
engine
and
check
for
pulsad

voltage
signal
.
"
Repeat
for
each
injector
.

NOTE
-

To
quick-check
if
en
injectorfunctioning,
place
a
screw-
driver
or
stethoscope
on
the
injector
with
the
engine

running
.
If
the
injector
is
operating,there
should
been

audible
buzz
.

FUEL
DELIVERYTESTS

130-
1
6



FUEL
INJECTION

Throttie
position
sensor
(TPS),



Idie
speed
control
valve,
testing
and
replacing



testing
and
replacing

The
throttie
position
sensor
(TPS)
is
mounted
on
the
side
of



¡die
speed
is
maintained
by
the
ECM
via
the
¡die
speed
con-

the
throttie
housing
and
is
directly
connected
to
the
throttie



trol
valve
.
See
Fig
.
24
.
¡die
speed
is
adaptive
through
the
valve
shaft
.
The
ECM
sends
a
voltage
signal
to
the
potentiom-



ECM
and
no
¡die
speed
adjustments
can
be
made
.
Before
eter-type
sensor
and
monitors
the
voltage
that
comes
back
.



testing
the
valve,
confirm
that
the
throttie
position
sensor(TPS)
is
working
correctly
.

Check
TPS
function
by
disconnecting
the
harnessconnec-

tor
and
checking
reference
voltage
and
sensor
resistance
.

See
Table
e
and
Fig
.
23
.
If
voltage
is
not
present,
check
the

output
voltage
signal
from
the
ECM
and
check
the
wiring
be-
tween
the
sensor
and
the
ECM
.
If
the
sensor
resistance
is
in-
correct,
replace
the
throttie
position
sensor
.

NOTE
-

The
throttie
position
sensor
is
not
adjustable
.
If
test
re-
sults
are
íncorrect,
the
sensor
should
be
replaced
.

Table
e
.
Throttle
Position
Sensor
Tests

(DME
1
.7)

Testconditions



1
Terminais



1
Test
value

Harness
connec-



(
1
and
ground
in



15
VDC
(approx
.)
tor
disconnected,



harness
connector
ignition
on

0013235

Fig
.
23
.
Throttieposition
sensor
terminal
identification
on
M42
engine
.

Harnessconnec-



I
1
and
3
at
sensor



(
4k
ohms
(approx
.)
tor
disconnected,



terminais
ignition
off
Connector
dis-



1
and
2
at
sensor



Continuously
vari-
connected,
igni-



terminais



able
from
1-4
k
tion
off
.
Throttle



ohms
(approx
.)
with
rotated
from
¡die



out
interruption
to
fui]
position

BOSCH
DME
Ml
.
7
COMPONENT
TESTS
AND
REPAIRS

Fig
.
24
.
¡die
speed
control
valve
(arrow)
on
M42
engine
.

NOTE
-

"
The
tests
given
below
are
electrical
checks
only
.
They
do
not
check
the
mechanical
operation
of
the
valve
or
if
the
valve
is
sticking
or
worn
.
If
the
valve
is
suspect,
substituting
a
known
good
valve
is
the
best
way
to
check
for
amechanical
fault
.

1
.
Check
battery
(+)
voltage
to
valve
:

0013226

"
Disconnect
harness
connector
from
valve
.
"
Check
for
battery
voltage
at
terminal
2
(red/white
wire)
.
"
If
voltage
is
not
present
check
wiring
between
valve
and
main
relay
(terminal
87)
.

2
.
Check
that
ECM
signal
is
reaching
valve
:

"
With
engine
running,
check
that
¡die
speed
control
valve
is
audibly
buzzing
.
"
If
valve
is
not
working,
disconnect
wiring
harness
con-
nector
.

"
Connect
12V
probe
light
across
connector
terminais
.
"
Turn
ignition
key
on
;
probe
should
light
.
lf
probe
does
nof
light,
check
the
wiring
from
the
ECM
(pin
29)
to
the
valve
.
See
Table
h
.
lf
probe
does
light
but
¡die
quality
is
poor,
the
valve
is
most
likely
sticking
and
or
worn
and
should
be
replaced
.

BOSCH
DME
MM
AND
M33
.1

COMPONENT
TESTS
AND
REPAIRS

Consult
Table
a
for
engine
application
information
for
the

Bosch
DME
3
.1
and
3
.3.1
systems
.

The
DME
3
.1
and
DME
3
.3
.1
systems
are
similar
in
opera-

tion,
with
knock
control
and
VANOS
operation
being
the
key

differences
.
DME
3
.1
engines
arenot
equipped
with
VANOS

or
knock
detectors,
while
the
DM
E3
.3
.1
system
is
.

CA
UTION-

Use
onty
a
digital
multimeter
when
testing
wiring
.
Use
of
an
analog
VOM
may
damage
the
engine
control
module
.

Fig
.
25
.
Mass
air
flow
sensor
.
Hot
wire
sensor
usedon
carswith
DME
Electrical
tests
of
the
main
and
fuel
pump
relays
and
the



3
.1
(1992
6-cylinder
models)
.

DME
engine
control
module
(ECM)
are
covered
earlier
in
this

section
.
Fuel
pump
tests
are
covered
in
160
Fuel
Tank
and



CAUTION-
Fuel
Pump
.
Use
only
a
digital
multimeter
when
checking
the
mass
air
flow
sensor
.
An
analog
meter
can
dam-
Mass
Air
Flow
Sensor



age
theair
flow
sensor
.

There
are
two
types
of
mass
air
flow
sensors
used
onthe



1
.
Disconnect
air
flow
sensor
from
air
cleaner
only
.
Leave

cars
covered
by
this
section
.
Testing
procedures
vary
de-



it
connected
to
duct
leading
to
intake
manifold
and

pending
on
type
installed
.
The
airflow
sensor
is
not
adjustable



leave
wiring
harness
connected
.

and
must
only
be
tested
with
a
digital
multimeter
.

Mass
Air
FlowSensor
Variants

"
1992
M50
engine

DME
M3
.1
.
.
.
.
...
..
mass
air
flow
sensor-hot
wire

"
1993-1995
M50
and
S50US

DMEM33
.1)
.
...
...
.
mass
air
flow
sensor-hot
film

Mass
air
flow
sensor
(hot
wire),

testing
and
replacing

When
the
engine
is
running,
a
current
is
used
to
heat
a
thin

wire
in
the
center
of
the
sensor
.
See
Fig
.
25
.
The
current
in
the

wire
is
regulated
to
maintain
a
temperature
of
100°C
more

than
the
air
passing
over
it
.
The
current
used
to
heat
the
wire

is
electronically
conneced
into
a
voltage
measurement
corre-

sponding
to
the
mass
of
intake
a¡
r
.

To
keep
the
wire
clean,
it
is
heated
to
a
temperature
of
about

1,000°C
(1,830°F)
for
one
second
.
This
"burn-off"
cycle
takes

place
automatically,
four
seconds
after
the
engine
is
tumed
off
.

lf
thehot
wire
breaks
or
if
there
is
no
output
from
the
air
flow

sensor,
the
ECM
automatically
switches
to
a
"limp-home"

mode
and
tucos
on
the
Check
Engine
light
.
The
engine
can

usually
be
started
and
driven
.
The
air
flow
sensor
has
no
inter-

nal
moving
parts
and
cannot
be
serviced
.

FUEL
INJECTION



130-
1
7

2
.
Start
engine
and
run
it
to
normal
operating
temperature
.

3
.
Rev
engine
toat
least
2,500
rpm,then
shut
it
off
.
Look

through
meter
at
hot
wire
.
After
approximately
four
sec-

onds
wire
should
glow
brightly
for
about
one
second
.

NOTE
-

If
the
wire
glowsas
specified,
then
the
airflow
meter
and
ECM
are
probably
operating
correctly
.
lf
the
wire
does
not
glow,
continue
testing
.

4
.
lf
the
wire
does
not
glow,
remove
air
flow
sensor
and

look
through
it
to
see
if
wire
is
broken
.
lf
wire
is
broken,

meter
will
have
to
be
replaced
.

5
.
Reinstall
air
flow
sensor
and
harness
connector
.
Peel

back
rubber
bootfrom
harness
connector
.
Working

from
rear
of
connector,
connect
digital
voltmeter
across

terminals
1
and
4
.
See
Fig
.
26
.

6
.
Start
and
rev
engine
toat
least
2,500
rpm,thenshut
it

off
.
After
about
4
seconds,
voltage
should
riseto
about

4
volts
for
about
one
second
.
lf
voltage
is
present,
but

wire
does
not
glow,
air
flow
sensor
is
faulty
and
should

be
replaced
.

7
.
lf
voltage
is
not
present
in
step
6,
turn
ignition
key
on

and
check
for
voltage
and
ground
at
sensor
.
There

should
beground
at
pin
4
.
There
should
be
positive
(+)

battery
voltage
at
pin
2
.

BOSCH
DME
M3
.1
AND
M32
.1
COMPONENT
TESTS
AND
REPAIRS

130-18



FUEL
INJECTION
The
engine
coolant
temperature
(ECT)
sensor
sends
con-

tinuous
engine
coolant
temperature
information
to
the
ECM
.
Fig
.
26
.
Mass
air
flow
sensor
terminalidentifcation
on
carswith
DME



As
temperature
increases
sensor
resistance
decreases
.
M3
.1
fuel
injection
.

Mass
air
flow
sensor
(hot
film),

testing
and
replacing

MOTE-

A
burn-off
cycle
is
not
used
on
hot
film
sensors
.

8
.
With
ignition
off,
disconnect
harness
connector
from
air



ECT
Sensor
Location
flow
sensor
.
Using
a
digital
multimeter,
check
resis-



"
M50/S50US
engine
............
left
side
of
cylinder
tance
at
terminals
listed
.



head
under
intake
manifold

Air
Flow
Sensor
Test
Values
(DMEM3
.1)

"
Terminals
5
and
6
.
.
.
.........
..
.
..
....
3-4
ohms

If
any
faults
are
found,
check
wiring
lo
and
from
the
ECM
.
Make
ECM
pinout
test
as
listed
in
See
Table
i
.
Main
power
to
air
flow
sensor
comes
from
DME
main
relay
.

On
cars
with
DME
M3
.3
.1
a
hot
film
mass
air
flow
sensor
is
used
.
When
the
engine
is
running,
a
current
is
used
lo
heat
a
thinfilm
in
the
center
of
the
sensor
.
This
current
is
electroni-
cally
converted
into
a
voltage
measurement
corresponding
to
the
mass
of
intake
air
.

If
thehot
film
breaks
or
if
there
is
no
output
from
the
air
flow
sensor,
the
ECM
automatically
switches
to
a
"limp-home"
mode
and
tucos
on
the
Check
Engine
light
.
The
engine
can
usually
be
started
and
driven
.
The
air
flow
sensor
has
no
inter-
nal
moving
parts
and
cannot
be
senricedor
adjusted
.

CA
UTION-

Use
only
a
digital
multimeter
when
checking
the
mass
air
flow
sensor
.
An
analogmetercan
dam-
age
the
air
flow
sensor
.

BOSCH
DME
M3
.
1
AND
M32
.1
COMPONENT
TESTS
AND
REPAIRS

1
.
Disconnect
harnessconnector
from
air
flow
sensor
.

2
.
Turn
ignition
on
and
check
for
voltage
and
ground
at

connector
.
There
should
beground
at
pin
1
.
There

should
be
positive
(+)
battery
voltage
at
pin
3
.
If
any
faults
are
found,
check
wiring
to
and
from
ECM
.
Make
ECM
pinout
test
.
See
Table
j
.

NOTE-

Positive
(+)
battery
voltage
to
air
flow
sensor
comes
from
DME
main
relay
when
the
ignition
is
switch
on
orengine
running
.

Engine
coolant
temperature
(ECT)
sensor,

testing
and
replacing

0012704
Fig
.
27
.
Engine
coolant
temperature
(ECT)
sensor
(A)
is
located
be-
neath
top
engine
cover
(B)
and
crankcase
vent
hose
(C)
.
M52
engine
shown
.
M50
is
similar
.

1
.
Check
ECM
reference
voltage
to
sensor
:
"
Disconnect
harnessconnector
from
ECT
sensor
.
"
Turn
ignition
keyon
.
"
Check
for
5
volts
between
supply
voltage
wire
(brown/red)
wire
of
harness
connector
and
ground
.
"
Turn
ignition
key
off
.
"
If
voltage
is'
not
present
or
incorrect,
check
wiring
from
ECM
and
check
referencevoltage
output
at
ECM
(pin
78)
.
See
Table
i
(DM
E
3
.1)
or
Table
j
(DME
3
.3
.1)

2
.
Check
ECT
sensor
resistance
:

"
With
harnessconnector
disconnected,
check
resis-
tance
acrosssensor
terminals
.
"
Compare
tests
results
to
values
in
Table
f
.

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
.