2001 BMW 525i electronic

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100-4
I Engine-General
The M62 90" V8 engine uses four valves per cylinder, double
overhead camshafts and light alloy cylinder head and cylin-
der
bloclc engine construction.
On 1997 and 1998 540i models, Bosch engine management
systems are utilized. Table a lists engine management sys-
tem applications.
4 For the 1999 model year, the M62 TU VANOS engine was in-
troduced to the 540i models. This engine is primarily a carry-
over from the earlier M62 engine, but contains many unique
identifying components and technology:
Variable camshaft timing (VANOS) for the intake valves.
Bosch ME 7.2 engine management system with electronic
throttle control. There is no accelerator cable connecting
the throttle pedal to the throttle housing in these cars.
Compact water-cooled generator (alternator).
E39 vehicles are equipped with sophisticated self-diagnostic
engine management systems. These systems monitor and
store diagnostic fault information. If the malfunction indicator
lamp (MIL) illuminates, the first diagnostic test should be to
connect a dedicated scan tool for BMW automobiles and in-
terrogate the fault memory.
If the malfunction indicator light (MIL) comes on orflashes, it
indicates that an emissions-related fault has occurred and
that fault information is stored in memory within the ECM.
4 The MIL in E39 cars displays one of these warning graphics
in the instrument cluster.
The diagnostic capabilities of these systems have the poten-
tial to save hours of diagnostic time and prevent incorrect
5 placement. See OBD On-Board Diagnostics.

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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 3-56
I Cvlinder Head Removal and Installation
- Installation of the remaining parts is reverse or removal, not-
ing the following:
- Refill cooling system as described in 170 Radiator and
Cooling System.
Change engine oil and filter as described in
020 Mainte-
nance.
If necessary, adjust accelerator cable.
a Reconnect battery.
CAUTION- To prevent damaging the engine electronic systems, installall
ground wire previously removed, including the ground wires
for the
ionition coils.
Tightening torque Coolant drain
pluq to cylinder bloclc 25 Nm (1 8 ft-lb)
Radiator cooling fan to coolant pump 40 Nm (30 ft-lb) -
Radiator drain screw to radiator 2.5
Nm (22 in-lb)
spark plug to cylinder head 25
Nm (1 8 ft-lb)
CYLINDER MEAD REMOVAL AND
INSTALLATION (M62 ENGINE)
This procedure covers cylinder head removal and installation
for the
M62 V-8 engine. Procedures forthe M62 TU VANOS
engine are not covered in this manual.
Intake manifold, left cylinder head, and right cylinder head re-
moval and installation are written as separate procedures.
The intake manifold must be removed before the cylinder
heads can be removed.
WARNING
-
Due to risk of personal injuv be sure the engine is cold be-
fore beginning the removal procedure.
Cylinder head removal and installation requires multiple spe-
cial service tools. Read the entire procedure before beginning
the repair.
Intake manifold, removal and installation,
M62 engine
- Disconnect negative (-) battery cable.
CAUTION- Prior to disconnecting the
batterj read the baitery discon-
nection cautions
in 001 General Cautions and Warnings.

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I Cylinder Head and Valvetrain
- Remove adjustable primary timing chain tensioner tool and
reinstall primary chain tensioner cylinder to cylinder head.
Tightening torque
Primary chain tensioner cylinder
to 70 Nm (52 ft-lb)
cylinder head
- Remove flywheel locking tool from crankcase. Replace spe-
cial tool bore sealing plug.
- Remove camshaft locking tools from cylinder head
Install intake camshaft cover and cylinder head cover.
Check for correct seating of half-moon seals (A) in back of
cylinder head cover.
Use a small amount of Three Bond
8 1209 or equivalent
sealing compound at corners
(B) of half-moon cutouts.
Seat gasket and seal corners at VANOS unit with Three
Bond
@ 1209.
Tightening torque Cylinder head cover to cylinder head
(M6) 10 Nm (89 in-lb)
- Installation of the remaininq parts is reverse or removal, not- -
ing the following:
Change engine
011 and f~lter as descr~bed in 020 Mainte-
nance.
Reconnect battery.
To prevent damaging the engine electronic systems, install
all ground wire previously removed, including the ground
wires for the ignition coils.
Tightening torque
-
Radiator cooling fan to coolant pump 40 Nm
(30 ft-ib)
Spark plug to cylinder head
25 Nm (18 ft-ib)

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1 17-2
Camshaft Timing Chain
This repair group covers timing chain and VANOS repair
information for the following engines:
M52 (Single VANOS 6-cylinder engine)
M52
TU and M54 (Double VANOS engines)
M62 (Non VANOS
V-8 engine)
NOTE-
The M62 TU V-8 engine with VANOS Variable Camshaft
Timing repair information is not included.
NOTE-
See 100 Engine General for engine code and application
information.
Worn timing chains and sprocltets can lead to noisy operation
and erratic valve timing. Afaulty tensionercan also cause tim-
ing chain noises.
For specific repair procedures, refer to the appropriate repair
group:
020 Maintenance
113 Cylinder Head Removal and Installation
119 Lubrication System
121 Ignition System
170 Radiator and Cooling System
Special tools
Special BMW service tools are needed to perform the service
and repairs procedures covered in this repair group. Many of
these tools are expensive and only available through an au-
thorized BMW dealer. Be sure to read each procedure thor-
oughly before starting a job to determine which special tools
will be necessary.
In addition, Double VANOS system diagnosis can only be
carried out by using BMW specific electronic scan tools, such
as BMW
DISplus, MoDiC or equivalent.
4 Torque wrench wl flex extension
(Tool No. BMW 00
9 250)

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120-3
Ignition System
Warnings and cautions
The ignition system produces dangerous high voltage. In ad-
dition the sensitive electronic components can be damaged
if
proper precautions are not adhered to.
WARNING-
* Do not touch or disconnect any cables from the coils while
the engine is running or being
cranked by the starter.
The ignition system produces high voltages that can be
fatal. Avoid contact with exposed terminals. Use ex-
treme caution when working on a car with the ignition
switched on or the engine running.
- Connect and disconnect tlie DME system wiring and
test equipment leads only when the ignition is
OFF:
Before operating the starter without starting the engine
(for example when
making a compression test) always
disable the ignition.
CA
U TIOW-
Do not attempt to disable the ignition by removing the coils
from the spark plugs.
Connect or disconnect ignition system wires, multiple
wire connectors, and ignition test equipment leads only
while the ignition is
off Switch multimeter functions or
measurement ranges only with the test probes discon-
nected.
* Do not disconnect the battery while the engine is run-
ning.
A high impedance digital multimeter should be used for
all voltage and resistance tests. An LED test light
should be used in place of an incandescent-type test
lamp.
In general, make test connections only as specified by
BMW as described in this manual, or as described by
the instrument manufacturer.
Engine management
BMW €39 engines use an advanced engine management
system known as Digital Motor Electronics (DME). DME in-
corporates on-board diagnostics, fuel injection, ignition and
other engine control functions. DME variants are listed in
Table a. Engine management systems.
Second generation On-Board Diagnostics
(OED II) is incor-
porated into the engine management systems used on the
cars covered by this manual. Use a BMW-specific electronic
scan tool, or a "Generic"
OED II scan tool to access Diagnos-
tic Trouble Codes (DTCs). DTCs can help pinpoint ignition
ine management problems.

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I lgnition System
Additional information about DTCs and engine management
system electronic system diagnosis is provided in
OBD On-
Board Diagnostics.
Table a. Engine management systems
Year
l~ngine I Engine type IDME svstem I - I - . . I
Ignition system
1997-1 998
1997
1998
1999-2002
4 All engines use a distributorless ignition system with individ-
ual ignition coils for each cylinder. There is no distributor cap
or ignition rotor.
4 Each coil is controlled and monitored by the Engine Control
Module (ECM) on a cylinder-by-cylinder basis.
1999-2000
1~52 TU 16-cylinder l~iemens MS
42.0
M62
M62
M62TU
Siemens MS 41 .I M52 6-cylinder
V-8
V-8 V-8 Bosch
M 5.2
Bosch M 5.2.1
Bosch ME 7.2

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Lnition switch
4 The positive (+) power supply to the ignition coils comes to
the ignition switch via an unloader relay. When the ignition
switch is turned on, the relay closes, to provide voltage to the
ignition coils. The coils are then actuated at the negative side
by the engine control module.
NOTE-
Schematic diagrams shown are for illustrative purposes only.
See ELE Electrical Wiring Diagrams for engine manage-
ment specific wiring information.
WARNING- Do not touch or disconnect any cables from the coils while
the engine is running or being cranked by the starter:
The ignition system produces high voltages that can be
fatal. Avoid contact with exposed terminals. Use ex-
treme caution when
working on a car with the ignition
switched on or the engine running.
* Connect and disconnect the DME system wiring and
test equipment leads only when the ignition is
OFF
Before operating the starter without starting the engine
(for example when
making a compression test), always
disable the ignition.
4 Knock sensors (arrows) monitor the combustion chamber for
engine-damaging knock. Six-cylinder models (shown) use
two sensors with each sensor monitoring three cylinders.
V-
8 models use four sensors, each monitoring two cylinders. If
engine
knock is detected, the ignition point is retarded by the
ECM.
I Ignition advance Ignition timing is electronically mapped and not adjustable.
The ECM uses engine load, engine speed, coolant tempera-
ture, knock detection, and intake air temperature as the basic
inputs for timing control.
A three dimensional map similar to
the one shown is digitally stored in the ECM.
- The initial ignition point is determined by the crankshaft
speed sensor during cranking. Once the engine is running.
timing is continually adjusted based on operating conditions.