1999 BMW 540i Ground terminal location

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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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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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Camshaft Timing chain1
- Disconnect negative cable (-) from battery.
CAUTION-
Prior to disconnecting the battery, read the battery discon-
nection cautions given
in 001 General Cautions and
Warnings.
4 Removing top and side engine covers:
Press down on locking pins (arrows) to release locks. Lifl
intake manifold cover straight up to remove.
Pry out caps from side covers.
Remove fasteners
and covers.
NOTE-
Some early models use
pry out trim caps and fasteners to
hold the top cover in place.
Disconnect electrical harness connectors at ignition coils
(A).
Remove left and right side ignition coil mounting fasteners
and coils.
NOTE-
Make note of location of ground strap (arrow).
Remove spark plugs.
- Remove posltlve (+) terminal cable from left cylrnder head
cover.
- Unbolt left and right side cable ducts from fuel rail
Remove air filter housing and mass air flow sensor:
Disconnect mass air flow sensor and intake air tempera-
ture sensor electrical harnesses
(A and B).
Remove air filter housing mounting fastener (arrow)
Loosen intake hose clamp
(C).
Remove air filter housing with mass air sensor and intake
duct from throttle body assembly.

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Camshaft Timing Chain LL. .- - - - I
4 Remove left and right side ignition coils and spark plugs:
- Disconnect electrical harness connectors at ignition coils
(A).
Remove left and right side ignition coil mounting fasteners
and coils.
NOTE-
Make note of location of ground strap (arrow).
Remove sparlc plugs.
- Remove positive (+) terminal cable from left cylinder head
cover.
- Unbolt cable ducts from fuel rail at left and right sides.
Disconnect fuel injector electrical connectors from injectors:
Pry corner of wire
loclc clip (arrow) to release connector.
Repeat for remaining injectors.
* Lift off wiring ducts.

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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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130-28
Fuel Injection
ECM Relay
4 Check for voltage at terminal 6 (30) at reiay socket
If battery voltage is present continue testing.
if battery voltage is not present, check fuse 109 (80-amp
fusible link) under passenger seat carpet. See 610 Electri-
cal
Component Locations.
- Reinstall relay and turn ignition on. Gain access to back side
of reiay socket and check for ground at terminal
4.
If ground is present continue testing.
If ground is not present, signal
from ECM is missing. Check
wire between ECM and relay.
- With ignition on and reiay installed, check lor battery voltage
at terminal
2.
If battery voltage is present, relay has energized and is
functioning correctly.
If battery voltage is not present and
ail earlier tests are OK,
relay is faulty and should be replaced.
NOTE-
If no faults are found during testing but power is not reaching
the ECM or other components, check the fuses
in the fuse
carrier
X8680 in the E-box.
Mass air flow (MAF) sensor, checking and
replacing
4 The hot f~lm mass air flow (MAF) sensor sends a varying volt-
age (approx. 0.5 - 4.5 vdc) to the ECM representing the mea-
sured
Intake air. The alr mass input signal is produced
electron~caily uslng an electrically heated metal fllm in the air
flow stream.
The ECM relay provides the operating voltage to the MAF
sensor. As air
flows through the sensor, the film is cooled. To
maintain the film at a constant temperature, additional current
is necessary. It is this additional current that is the basis lor
the input signal.
If there is no output signal from the MAF sensor, the ECM op-
erates the engine using the throttle position and engine rpm
inputs. A faulty MAF sensor illuminates the MIL.

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130-50
Fuel Injection
Bosch M5.2
ECM relay
1 HoL al ail iirnel XOL a1 ail limes
i--[-----i F109 (BOA) electronics I L.$.....: .I:
ECM relay . . . . . . . . . ,
8,s
:,
6 1 .. ... ~~.~~. . ...... .-, Engine control ii~~-~.~~..~ ........ ~~~~~~.~~~~:. module relay -;I
Of?
,c,;,,,
< With ignition off, remove ECM relay (arrow) in electronics
box (E-box) at right rear of engine compartment.
NOTE-
Relay locations can vary. Conh relay identification by
matcliing wiring colors and terminal numbers.
4 Check for voltage at terminal 6 of main relay socket (30-red
wire). On M5.2 cars also check for battery voltage at terminal
8.
. . . . . . . . . ,
If battery voltage is present, continue testing
.
If battery voltage is not present, check large red wire(s) in
relay socltet. See
ELE Electrical Wiring Diagrams.
%P,,tt
- Reinstall relay and turn ignition on. Gain access to underside
of relay socket and
checlc for ground at terminal 4 (85-brown
wire).
. . . . . . . . . . . . - - - - - - - - - . - - - . . l ,,-. ; Engine i f .: , ; Fuse carrier .,A . :engine /;is? /control L.!.!! .... 1.: ...... !.::..! I lij :module electronics If
ground is present, continue testing
If ground is not present, signal from ECM is missing. Checic
wire between ECM and relay.
4 With ignition on and relay installed, check for battery voltage
at terminal
2 (87-redlwhite wire). On M5.2.1 cars also checlc
for battery voltage at terminal 5.
If battery voltage is present, relay has energized and is
functioning correctly.
If battery voltage is not present and all earlier tests are OK,
relay is faulty and should be replaced.