1999 BMW 540i Grounds

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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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100 Engine-General
........ General ........................... .I0 0.2 Driveability Troubleshooting 100-4
....................... Engine identifying features ............. .I0 0.3 System voltage 100-5
........................ Main grounds 100-5

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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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100-6
( Engine-General
The main grounds for the fuel and ignition circuits of the DME
system are illustrated below; see 610 Electrical Component
Locations for additional ground and component locations.
4 Ground for engine management system in right rear of en-
gine compartment on E-box bulkhead (arrow).
6-cylinder models: Grounds
for ignition coils (arrows)
4 V-8 models: Grounds for ignition coils, at cylinders 3
(arrow) and 7.
4 Fuel pump ground (arrow) below right tail light in luggage
compartment.
NOTE-
Ground location for sedan shown, wagon models may
differ.

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Cylinder Head Removal and Installation
4 If applicable, remove secondary air injection pump:
Disconnect hose at one-way valve
(A).
Remove bolts at support bracket on strut tower (arrows).
Disconnect electrical harness from bottom of secondary
air injection pump.
Remove mounting bracket from strut tower.
4 Remove ignition coils:
* Disconnect ignition coil harness connectors.
Remove coil mounting fasteners.
Remove coils.
* Remove ground straps.
CA UTIOI\C
Note location of all ground wires. Failure to reinstall grounds
can result in permanent damage to engine control module or
ignition system components.
Set coil harness to side of engine compartment
- Remove cylinder head cover mounting fasteners and remove
cylinder head cover.
NOTE-
The cylinder head cover mounting bolt insulators and gas-
ltets should be reinstalled in their original locations. Male
note of their arrangement during removal.
- Remove spark plugs
4 Remove oil baffle cover from above intake camshaft.

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Gaskets and seals 01
0-9
Gearshift automatic transmission
adjusting
250-7
shift interiock. checkino function " 250-9
shiftloclc. checicino function 250-8 - manual transmission
gearshift lever, removingiinstalling
250-5
steptronic 250-7
General module (GM Ill)
600-8
see also Central locking
Generator see Battery, starter, alternator
Glass see Door window
Glove compartment
513-16
see also
Global positioning system
(GPS)
620-9
Grill
see Exterior trim
Grounds
100-5
Guide link
see Rear suspension, suspension
arms
Halogen headlight
630-5
Hand brake
see Brakes, pariring brake
Handle, door
see Door
locks
Hatch seeTailgate
Hazard warning switch
see Switches Headlight
housing trim
see Exterior trim
washer611-17 see also Lights
Headlight spray
nozzle
611-17
Headlight switch
see Switches
Heater core
see Heating
Heater valve
see Heating
Heating lieater core, replacing
640-18
lheater core temperature sensor,
removingiinstalling
640-12 heater valve, replacing 640-17
IHKA housing, removinglinstallin~
640-21
see also NC
Hood
410-6
Hood latch and release
410-10
Hydraulic valve lifters
see Cylinder head and valvetrain
IAT
(lntalce air temperature) sensor
see 130
under appropriate fuel
injection system
idle speed control valve
see 130
under appropriate fuel injection system
Idle stabilizer
see 130
under appropriate fuel
injection system, idie speed controi
valve
idler arm
320-30
lgnition coll
see lgnition system
lgnition interlock
320-13
lgnition lock cylinder
removingiinstalling
320-1 1. 612-4
lgnition switch
seeSwifches
Ignition system
diagnosis checking for
spark 120-10
disabling ignition system 120-10 misfire detection 120-6
oscilioscope diagrams 120.6
troubleshooting 120-6
camshaft position sensors 120-14 coils 120.10
crankshaft speed sensor 120-12 firing order 120-9
knoclc sensors 120-16
IHKA
see NC
IHKR see NC
Injector
see 130 under appropriate
fuel
injection system, luel injector
Input shaft
oil seal
see Manual transmission, oil seals
Inspection
see Maintenance
Instruments GPS see Global positioning system
(GPSI layout 6202
removingiinstalling 620-8 self-testing 620-6
Intake air temperature sensor (IAT)
see 130 under appropriate fuel
injection system
Intake manifold
removingiinstalling
6-cvlinder enoine 110-10. 113-8. 113-22 -
V-8 engine (M62) 113-56
Integral link
see Rear suspension, suspension
arms
lnterior lights
see Lights
lnterior protection
(FISIUIS) 515-25
lnterior trim
513-13
lnterior ventilation microfilter see
NC, ventilation microfiller