Vol 2 BMW 528i 2000 E39 Owner's Manual

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120-7
Ignition System
Spark plug electrode gap /Too small /TOO big
Table
b. Ignition secondary voltage diagnostics
Secondary
voltage low
Fuel air mixture
I I Too lean
Secondary
voltage high
Spark plug electrode
Worniburnt
4 The illustration shows normal scope trace of spark at idle.
1. Start of ignition voltage peak
2 Level of ignition voltage
3. Level of combustion voltage
4. Period of combustion
5. Combustion curve characteristics
6. Start of decay process
7. Termination oscillations
Spark plug electrode
temperature
Engine compression
Spark plug wires
4 Short combustion period (indicates large spark plug gap).
Too
high
Too
low
I"" 9, 10 I" to I!, r) i" 21 10 il bW,rn?7G
Too low
Too high
Faulty
4 Ignition spark at idle speed.
A - Normal ignition voltage peak (spark plug is good).
B - Low voltage peak is an indication of a closed plug gap.
C
- High voltage peak indicates an open plug gap.
< Long combustion period (indicates small spark plug gap).
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I lgnition System
4 Normal combustion period at idle.
4 Normal oscilloscope pattern for ignition system at idle.
15. 15
4 lgnition voltage peaks at idle.
1. Normal ignition peaks.
2. Downward peak (arrow) is shortened (ignition coil is
defective).
3. Downward peak (arrow) is missing completely (ignition
coil is defective).
4 Defective ignition coil.
1. Short spark period.
2. The spark voltage line (arrow) is very slight
< Defective ignition coil.
1. Normal combustion period.
2. Absence of spark voltage line (arrow).
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< Ignition voltage peaks in response to sudden acceleration
load:
1. Normal ignition pattern. Beginning of dying out pattern
is not much higher than ignition voltage peak.
2. Beginning of dying out pattern considerably higher than
ignition voltage peak. Fault in injection system:
Lean fuel mixture
Defective fuel injector
Low compression in cylinder
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Ignition firing order
Normal secondary voltage patterns
(4-cylinder pattern shown).
4 Each ignition coil is mounted above the corresponding spark
plug.
- Number one cylinder is located at the front on 6-cylinder
models.
Number one cylinder is located at the right (passenger side)
front on
V-8 models. Cylinder firing order is shown.
Firing order
M52 - M52 TU - M54 6-cylinder 1-5-3-6-2-4
M62 - M62 TU V-8 1-5-4-8-6-3-7-2

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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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121-1
121 Battery. Starter. Alternator
General ........................... .I2 1.2
Special tools ........................ .I2 1.2
Engine electrical system ............... .I2 1.2
Battery Safety Terminal ............... .I2 1.3
Warnings and cautions ................. 121 -4
Battery ............................ 121-5
Battery testing ...................... .I2 1.5
Hydrometer testing ................... .I2 1.5
Battery open-circuit voltage test ......... .I2 1.6
Battery load voltage test ................ 121 -6
Closed-circuit current measurement ..... .I2 1.7
Battery charging ...................... 121 -9
Battery safety terminal, replacing ......... 121-9
Alternator (generator) ............. .I2 1.10
Alternator. basic .................... .I2 1.11
Alternator with multi-function
control (MFR)
...................... .I2 1.11
Water-cooled alternator ............... 121 -12
Charging System Troubleshooting . 121-12
Charging system quick-check .......... 121-13
Charging system. checking ............ 121-13
Alternator. removing and installing
(6-cylinder engine)
.................. 121 -1 5
Alternator. removing and installing
(M62 engine. air cooled)
.............. 121-16
Alternator. removing and installing
(M62 TU engine. water cooled) ......... 121-1 8
Starter ........................... 121 -1 9
Starter troubleshooting ............... 121 -1 9
Starter. removing and installing
(6-cylinder engine)
.................. 121-20
Starter. removing and installing
(V-8 engine)
........................ 121 -21
Solenoid switch. removing and installing . . 121-23

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- -
Battery, Starter, Alternator
This section covers the battery, alternator, starter and associ-
ated components of the electrical system.
Troubleshooting information
forthese components isfound in
Table a. Battery, alternator and starter troubleshooting.
For additional electrical troubleshooting information, see
600 Electrical System-General.
Special tools
4 Automotive digital multimeter
CAUTION-
Only use a digital multirneter when testing automotive electri- I) cal components.
4 Closed-circuit current measurement adaptor
(Tool No.
BMW 61 2 300)
Engine electrical system
The alternator and starter are wired directly to the battery. To
prevent accidental shorts that might blow a fuse or damage
wires and electrical components, always disconnect the
negative
(-) battery cable before working on the electrical
system.
Various versions of alternators, voltage regulators, starters,
and batteries are used in
E39 cars. Replace components ac-
cording to the original equipment specification.

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Battery, Starter, ~lternatorl
@ TO fuse & relay panel Battery Safety Terminal
A Battery Safety Terminal (BST) controlled by the Multiple
Restraint System (MRS) control unit was introduced for mod-
el year 1998
vehicles. The system will disconnect electrical
power to the engine compartment
in the event of a significant
impact. The MRS system fires an encapsulated pyrotechnic
device
in the positive (+) battery terminal that disconnects
power to the engine compartment, but maintains power to
the exterior lights and interior of the vehicle.
point
002125~1
Table a. Battery, alternator and starter troubleshooting
1-
/Starter motor or solenoid faulty. l~est starter.
Symptom
Engine does not crank
Engine cranks slowly or
not at all, solenoid
clicits
when starter is operated.
I I
Battery will not stay IShort circuit draining battery. l~est for excessive current drain with everything
Probable cause
Fault
in immobilizer system (EWS)
-Clean Battery cables loose, dirty or corroded.
Battery discharged.
Battery to body ground cable in trunk
loose,
dirty or corroded
Poor connection at starter motor terminal
30.
Corrective action
Try another ignition key. If problem persists, contact
your authorized BMW dealer.
or replace cables. See 020
~aintenance.
Charge battery and test. Replace if necessary.
inspect ground cable. Clean, tighten or replace if
necessary.
Checlc connections, test for voltage at starter. Test for
voltage at neutral safety or clutch
interloclc switch.
charged more than a few
days.
I~atter~ faulty. /Test battery and replace if necessary.
Short driving trips and high electrical drain
on
charging system does not allow battery to
recharge.
. I
I Battery cables loose, dirty or corroded. Iclean or replace cables. See 020 Maintenance.
Evaluate driving
style. Where possible, reduce
electrical
consumption when malting short trips.
Drive
belt@) loose, worn or damaged.
IAlternator or voltage regulator faulty. /Test alternator and voltage regulator.
Inspect
or replace ribbed
belt@). See 020
Maintenance.

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Battery, Starter, ~iternatorl
The battery is mounted in the right side of the luggage com-
partment, concealed behind a trim panel. Battery capacity is
determined by the amount of current needed to start the vehi-
cle and by the amount of current consumed by the electrical
system. This will vary from model to model.
BMW batteries are rated by
amperelhours (Ah) and cold
cranking amps (CCA) rating, which are listed on the battery.
The Ah rating is determined by the average amount of cur-
rent 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
On F (-18" C) without drop-
ping below a specified voltage. Always replace the battery
with one having the same or higher ratings.
Battery testing
Battery testing determines the state of battery charge. On
conventional or low-maintenance batteries. the most com-
mon method of testing the battery is that
ofchecking the spe-
cific gravity of the electrolyte using a hydrometer. Before
testing the battery, check that the cables are tight and free of
- corrosion.
Hydrometer testing
Before hydrometertesting, load the battery with 15 amperes
for one minute. If the battery is installed in the vehicle, this can
be done by turning on the headlights without the engine run-
ning. The state of battery charge based on specific gravity
values are given in Table
b. Specific gravity of battery elec-
trolyte at
27" C (80°F).
The hydrometer indicates the specific gravity of the electro-
lyte. The more dense the concentration of sulfuric acid in the
electrolyte, the higher the state of charge
NOTE-
Electrolyte temperature affects hydrometer reading. Checlc
the electrolyte temperature with a thermometer. Add 0.004 to
the hydrometerreading
forevery 6°C (10°F) that the electro-
lyte is above 27°C
(80°F). Subtract 0.004 from the reading
forevery 6°C (10°F) that the electrolyte is below27"C
(80°F).

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.
Battery, Starter, Alternator
Table b. Specific gravity of battery electrolyte at 27°C (80°F)
Specific gravity State of charge
1.265 Fully charged
1.225 75% charged
1.190 50% charged
1.155 25% charged
1.120 Fully discharged
if the specific gravity is at
orabove 1.225, butthe battery lacks
Dower for
startinq, determine the battew's service condition
with a load volta& test. if the average specific gravity of the
six cells is below 1.225, remove the battery from the luggage
compartment and recharge.
Battery open-circuit voltage test
Before testing, load battery with 15 amperes for one minute
with battery load-tester or turn on headlights for about one
minute without engine running. Connect digital voltmeter
across battery terminals. Open-circuit voltage levels are giv-
en in Table
c. Open-circuit voltage and battery charge.
If open-circuit voltage is
OK but battery still lacks power for
starting, perform a load voltage test.
If open-circuit voltage is
below 12.4 volts, recharge battery
and retest.
Table c. Open-circuit voltage and battery charge
Open-circuit voltage State of charge
12.6 V or more
12.4 V
12.2v
12.0 v
Fully charged
75% charged
50% charged
25% charged
11.7Vorless Fully discharged
Battery load voltage test
A battery load tester is required for a load voltage test. The
test is made by applying a high resistive load to the battery
terminals and then measuring battery voltage. The battery
should be
fully charged forthe most accurate results. The bat-
tery cables must be disconnected before
malting the test. Re-
place the battery if the voltage is below that listed in Table d.
Battery load test
- minimum voltage.