1999 BMW 540i Ground terminals

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I General Warnings and Cautions
WARNINGS (continued)
. The air conditioning system is filled with chemical refrigerant,
which is hazardous. The AIC system should be serviced only by
trained technicians using approved refrigerant recoverylrecycling
equipment, trained in related safety precautions, and familiar with
regulations governing the discharging and disposal of automotive
chemical refrigerants.
. Do not expose any part of the AIC system to high temperatures
such as open flame. Excessive heat will increase system pres-
sure and may cause the system to burst.
Some aerosol tire inflators are highly flammable. Be extremely
cautious when repairing a tire that may have been inflated using
an aerosol tire inflator. Keep sparks, open flame or other sources
of ignition away
from the tire repair area. Inflate and deflate the
tire at least four
times before breaking the bead from the rim.
Completely remove the tire from the rim before attempting any re-
pair.
Cars covered by this manual are equipped with a supplemental
restraint system (SRS), that automatically deploys
airbags and
pyrotechnic seat belt tensioners
In the event oi a frontal or side
impact. These are explosive devices. Handled improperly or with-
out adequate safeguards, they can be accidently activated and
cause serious injury.
- The ignition system produces high voltages that can be fatal.
Avoid contact with exposed terminals and use extreme care when
working on a car with the engine running or the ignition switched
on.
. Place jack stands only at locations specified by the manufacturer.
The vehicle
illtino iack su~olied with the vehicle is intended fortire -. , . changes only. A heavy duty floor jack should be used lo lift vehicle
before installing
jacl( stands. See 010 General.
- Battery acid (electrolyte) can cause severe burns. Flush contact
area
with water, seek medical attention.
Aerosol cleaners and solvents may contain hazardous or deadly
vapors and are highly flammable. Use only in a well ventilated ar-
ea. Do not use on hot surfaces (engines, brakes, etc.).
Do not remove
coolant reservoir or radiator cap with the engine
hot. Danger of burns and engine damage.
CAUTIONS-
See also WARNINGS
- if you lack the slqills, tools and equipment, or a suitable worl(shop
for any procedure described in this manual, leave such repairs to
an authorized BMW dealer or other qualified shop.
BMW is constantly improving its cars and sometimes these
changes, both in parts and specifications, are made applicable to
earlier models. Therefore, part numbers listed in this manual are
for reference only. Always check with your authorized BMW deal-
er parts department for the latest information.
Before starting a job, make certain that you have all the neces-
sary tools and parts on hand. Read ail the instructions thorough-
ly, and do not attempt shortcuts. Use tools appropriate to the
work and use only replacement parts meeting BMW specifica-
tions.
Use pneumatic and electric tools only to loosen threaded parts
and fasteners. Never use these tools to tighten fasteners, espe-
cially on light alloy parts. Always use a torque wrench to tighten
fasteners to the tightening torque specification listed.
Be mindful of the environment and ecology. Before you drain the
crankcase, find out the proper way to dispose of the
oil. Do not
pour
oil onto the ground, down a drain, or into a stream, pond or
lake. Dispose of waste in accordance with Federal, State and
Local laws.
The control module for the anti-lock brake system
(ABS) cannot
withstand temperatures from a paint-drying booth or a heat
lamp
in excess of 203" F (95°C) and should not be subjected to tem-
peratures in excess of 185°F
(8S°C) for more than two hours.
- Before doing any electrical welding on cars equipped with ABS,
disconnect the battery negative
(-) terminal (ground strap) and
the ABS control module connector.
- Always make sure ignition is off before disconnecting battery.
Label battery cables before disconnecting. On some models, bat-
tery cables are not color coded.
Disconnecting the battery may erase fault code@) stored in control
module memory. Using special BMW diagnoslic equipment, check
lor
iauit codes prior to disconnecting the battery cables. If the mal-
I.mct on ndicator Ignt (MIL) s I. ..minaled. see OBD On-Board
Diaanostics
Tl11s iant is iuenlfted as lne Check Ena~ne oht
(1997-2000 models jor~ervlce Engine Soon light (2061 andlater
models). If any other system iaults have been detected (indicated
by an illuminated warning light), see an authorized BMW dealer.
If a normal
or rapid charger is used to charge battery, the battery
must be disconnected and removed from the vehicle in order to
avoid damaging the vehicle.
- Do not quick-charge the battery (for boost starting) for longer
than one minute. Wait at least one minute before boosting the
battery a second time.
* Connect and disconnect a battery charger only with the battery
charger switched off.
- Sealed or "maintenance free" batteries should be slow-charged
only, at an amperage rate that is approximately 10% of the bat-
tery's ampere-hour (Ah)
rating.
. Do not allow battery charging voltage to exceed 16.5 volts. If the
battery begins producing gas or boiling violently, reduce the
charging rate.
Boosting a sulfated battery at a high charging rate
can cause an explosion.

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020-22 Maintenance
1
- Installation is reverse of removal, bearing in mind the
following:
Lightly lubricate new
spark plug threads with
copper-based anti-seize compound.
Thread plugs into cylinder head by hand to prevent
cross-threading.
. Be sure to reinstall and tighten coil grounds.
Tightening torque Spark plug
to cylinder head 25 Nm (18 It-lb)
Interior ventilation microfilter, replacing
Two interior ventilation microfilters are used, one on each
side of the engine compartment at the fire wall.
< To replace the microfilter, unclip the wire fastener and
remove the cover.
Lift out the filter, and replace. Left side shown; right is
similar.
Replace cover and clip wire fastener to retain cover.
Battery, checking, cleaning, and replacing
The battery Is located in the right side of the luggage compart-
ment. Simple maintenance of the battery and its terminal
connections will ensure maximum starting periormance,
especially in winter when colder temperatures reduce battery
power.
Battery cables should be tight. The terminals, cable clamps
and battery case should be free of the white deposits that
indicate corrosion and acid salts. Even a thin layer of dust
containing conductive acid salts can cause battery discharge.

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Maintenance
- To remove battery corrosion:
Disconnect battery cables. Disconnect negative (-)cable
first.
* Remove battery from trunk
Clean terminal posts and cable clamps with a wire brush.
Clean main chassis ground terminal next to battery.
Corrosion can be washed away with a
baking soda and
water solution that will neutralize acid.
Reinstall battery and reconnect cable clamps, positive
(+)
cable first.
Lightly coat outside of terminals, hold down screws, and
clamps with petroleum jelly, grease, or a commercial
battery terminal corrosion inhibitor.
WARNING
-
Battery acid is extremely dangerous. Take care to keep it
from contacting eyes, skin, or clothing. Wear eye protection.
Extinguish all
smolihg materials and do not work near any
oaen flames.
CAUTION-
Prior to disconnecting the batteg read the battery discon-
nection cautions given in
001 General Cautions and
Warnings.
NOTE-
The original equipment battery in E39 models is mainte-
nance free. The original electrolyte will normally last the
entire service life of the battery under moderate climate con-
ditions.
Battery electrolyte should be maintained at the correct level
just above the battery plates and theirseparators. The correct
level is approximately
5 mm ('14 in.) above the top of battery
plates or to the top of the indicator
marks (if applicable). The
battery plates and the indicator marks can be seen once the
fillercaps are removed.
if theelectrolyte level is low, replenish
it by adding distilled water only.
4 The original equipment BMW battery is equipped with a
built-in hydrometer "magic eye"
(arrow). Battery condition is
determined by the color of the eye:
Green: Adequate charge
* Black: Inadequate charge, recharge
Yellow: Defective battery, replace
Batteries are rated by ampere hours (Ah), the number of
hours a specific current drain can be sustained before com-
plete discharge, or by cold cranking amps (CCA), the number
of amps available to crank the engine in cold weather
condi-

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Two common causes of driveability problems are incorrect
system voltage and bad grounds.
System voltage
Digital motor electronics (DME) requires that the system (bat-
tery) voltage be maintained within a narrow range of DC volt-
age.
DC voltage levels beyond or below the operating range,
or any
AIC voltage in the electrical system can cause havoc.
When troubleshooting an illuminated MIL, make sure the bat-
tery is fully charged and capable of delivering all its power to
the electrical system. An undercharged battery can amplify
AIC alternator output ripple.
To
make a quick check of the battery charge, measure the
voltage across the battery terminals with all cables attached
and the ignition off.
Afully charged battery will measure 12.6
volts or slightly more, compared to 12.1 5 volts for a battery
with a 25% charge.
The DME system operates at low voltage and current levels,
making it sensitive to small increases in resistance. The elec-
trical system is routinely subjected to corrosion, vibration and
wear, so faults or corrosion in the wiring harness and connec-
tors are not uncommon. Check the battery terminals
forcorro-
sion or loose cable connections. See 121 Battery, Starter,
Alternator for additional information.
If a battery cable connection has no
v~sible faults but is still
suspect, measure the voltage drop across the connection. A
large drop indicates excessive resistance, meaning that the
connection is corroded, dirty, or damaged. Clean or repairthe
connection and retest.
NOTE-
For instructions on conducting a voltage drop test and other
general electrical troubleshooting information, see
600 Elec-
trical System-General.
Visually inspect all wiring, connectors, switches and fuses in
the system. Loose or damaged connectors can cause inter-
mittent problems, especially the small terminals in the ECM
connectors. Disconnect the wiring harness connectors to
check for corrosion, and use electrical cleaning spray to re-
move contaminants.
Main grounds
Good grounds are critical to proper DME operation. If a
ground connection has no visible faults but is still suspect.
measure the voltage drop across the connection. A large volt-
age drop means high resistance. Clean or repair the connec-
tion and retest.
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11 3-6
Cylinder Head Removal and Installation
- Disable ignition system by removing DME main relay. See
610 Component Locations for relay location.
WARNING-
. The ignition system produces high voltages that can be fa-
tal. Avoid contact with exposed terminals and use
exfreme
caution when working on a car with the ignition switched on
or the engine running.
Do not touch or disconnect ignition
components while
the engine is running or being cranked by the starter.
Failure to remove the DME main relay or attempting to
disa-
bie the fuel andignition systems by other methods may result
in damaoe to the enoine control module
(ECM).
- - Remove plastic cylinder head cover(s)
,,I . ,. .*,.,,&- - Remove coil grounding straps.
I CAUTION-
I nition system components. I
- Remove coils.
- Remove spark plugs from all cylinders.
NOTE-
Check the spark plugs for oil deposits that may indicate poor
cylinder sealing, then set them aside in order. Used spark
plugs should be reinstalled in the same cylinder from which
they were removed.
4 Install compression gauge in first cylinder spark plug hole,
tight enough to form a good seal.
- With parking brake set, transmission in PARK or NEUTRAL,
and accelerator pedal pressed to floor, crank engine with
starter. Record highest value indicated by gauge.
NOTE-
* The compression gauge reading should increase with
each compression stroke and reach near its maximum
reading in about
4-6 strokes.
All cylinders should reach maximum compression in the
same number of
strolces. If a cylinder needs significantly
more strokes to reach
maximum compression, there is a
problem.

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.-
ignition System
Disabling ignition system
The ignition system operates in a lethal voltage range and
should be disabled any time engine service or repair work is
being done that requires the ignition to be switched on.
The engine management system can be disabled by remov-
ing the DME main relay. The relay is located in the electronics
box (E-box) in the left rear of the engine
compartment, be.
neath the interior microfilter housing.
CAUTION- Relay locations may
vary. Use care when identifying relays.
See
610 Electrical Component Locations.
Checking for spark
CAUTION-
If
a spark test is done incorrecth damage to the Engine Con-
trol Module
(ECM) or the ignition coils may result.
NOTE-
Spark plug replacement is covered in 020 Maintenance.
Check~ng for spark is d~fflcult on englnes wlth d~str~butorless
ignition systems.
Try removing the spark plugs and inspecting for differences between them.
A poor-firing plug may be wet with fuel and/or ~. - ~
black and sooty, but not always. If a coil is not operating, the
engine management system will electrically disable the fuel
injector to that cylinder. The key is to look for differences be-
tween cylinders.
Ignition coil assembly, testing and
replacing
C4 UTION-
Use a digital multimeter for the following tests. I
- Remove plastic engine cover from top of valve cover by pry-
ing off bolt covers and removing cover mounting bolts.
- Raise car slowly while constantly checking position of jack
and car.
- Disconnect harness connector from coil. Connect multimeter
between terminal 15
(+) in connector and ground.
4 Terminal identification are typically molded into connector. In
photo, terminals are from left to right: 1,
4a, 15.

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Ignition System
- Turn ignition on and check for battery voltage,
If battery voltage is not present,
checlt wire between termi-
nal
15 and the unloader relay. See ELE Electrical Wiring
Diagrams.
- Turn ignition off.
Remove coil and inspect coil housing for hairline
cracks or
leaking casting material. Replace any
cracked or leaking coil.
NOTE-
A leaky coil may indicate a faulty Engine Control Module
(ECM). Check ECM before installing a new coil.
CAUTION-
Note location of coilground straps before coil removal; rein-
stall in the same location.
Use a multimeter to test:
Coil primary resistance at coil terminals.
Sparlt plug connector resistance.
* Compare results to specification in Table c. lgnition coil
resistance.
Table c. Ignition coil resistance
Coil secondary
resistance
Spark plug connector:
Bosch 1 .O I( ohm t 20%
1.8 ir ohm t 20%
Component
Co~l prlmary
resistance
- Replace ignition coil or sparlt plug connector if resistance
readings do not meet specifications.
4 Remove ignition coil to be tested.
Install
BMW special tool 12 7 030 (A) on coil to be tested.
Connect ground jumper between coil mounting point
(B)
and engine ground point (C).
Clip scope high pick-up lead (D) around ignition lead.
Start engine.
Compare scope pattern with diagrams in Oscilloscope
di-
agnostic diagrams.
NOTE-
When replacing ignition coils, ensure that the replacements
Terminal
1 (-) and 15 (+)
are
from the same manufacturer with the same partlcode
numbers. If individual coils with the correct specifications are
not available. all coils should be
re~laced.
Resistance
0.8 ohms

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Battery, Starter, Alternator
Water-cooled alternator
The water-cooled alternator, used on 1999 and later M62 TU
engines, is a sealed unit housed inside the engine block wa-
ter jacket. It is cooled via the engine cooling system. It is a
"brushless" sealed unit that cannot be serviced. Maintaining
consistent alternator temperatures increases the life span of
the alternator, and elimination of the alternator cooling fan re-
duces alternator noise
significantly.
The M62 TU water-cooled alternator incorporates load start
reduction. This function is intended to shorten the duration of
engine starting, particularly at low ambienttemperatures. The
current load is limited to
20 amps during starting in order to re-
duce alternator braking torque on the engine. Following the
current limiting phase, full power output is then progressively
reached.
Charging system diagnostics requires special test equip-
ment. If the test equipment is not available, charging system
fault diagnosis can be performed by an authorized
BMW
dealer or other qualified repair shop. See Table a. Battery,
alternator and starter troubleshooting for general electri-
cal component troubleshooting.
Before checking the alternator, make sure the battery is fully
charged and capable of holding a charge. Check that the bat-
tery terminals are clean and tight and the alternator drive belt
is properly tensioned and not severely worn.
NOTE-
Some model require up to 15 second to reacli full alternator
output.
CA UTIOG
If the charge indicator light in the instrument cluster remains
on, the charge warning circuit in the instrument cluster may
be faulty. Check that the ground lead is securely
affached to
the grounding stud on the cylinder head
(A). Replacing the
instrument cluster before repairing the ground lead will both
damage the instrument cluster and cause the failure to
reoccur.