1998 BMW 528i power

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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.

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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, 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.

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121-8
/Battery, Starter, Alternator
NOTE-
Automatic transmission cars: ambershifier LED willgo out at
consumer cut-off.
4 Attach closed-circuit current measurement adaptor
(BMW special tool
61 2 300):
Connect red clamp (marked A -BATT (+)) to positive bat-
tery terminal.
Connect
black clamp (marked B -CHASSIS) to chassis
ground point.
NOTE-
Green LED will light up to indicate correct installation of
closed-circuit current measurement
adaotor.
< Connect blaclc clamp (marked B - BATT (-)) to negative bat-
tery terminal. Green
LED light will go out.
NOTE-
Any electrical overloading will be indicated at this point by
lighting the red
LED. If the red LED lights up, check the adap-
tor connections.
< Set multimeter (A) to 10 amp measuring range and connect
it to adaptor.
NOTE -
Set multimeter to record average readings.
Ifpossible, turn offpowersaving features of multimeter
which prevent a long term (overnight) test by automatically
powering down
meter.
- Disconnect battery ground strap (B) at chassis mounting
point.
- Measure closed-circuit current using multimeter.
- Typical average closed-circuit current for E39 vehicles is
40 mA. Readings over 50 mA must be further investigated.

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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.

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Battery, Starter, ~lternatorl
Alternator, removing and installing
(6-cylinder engine)
A replacement alternator should have the same rating as the
original. Alternator manufacturer and ampere rating are nor-
mally marked on the alternator housing.
- Disconnect negative (-) battery cable.
CAUTION-
Prior to disconnecting the batteg read the battery discon-
nection cautions given
in 001 General Warnings and Cau-
I tions.
Remove complete air filter housing:
Loosen intake duct hose clamp
(A) at throttle assembly.
Loosen clamp and remove idle control hose from intake
duct
(B) and disconnect idle speed control valve electrical
harness connector.
Disconnect electrical harness connector
(C) from mass air
flow sensor.
* Remove air filter housing mounting screw (D),
Disconnect vent tube (E).
Loosen air intake duct clamp (F).
Carefully lifl air filter housing out of engine bay.
Remove alternator drive belt. See belt removal procedures in
020 Maintenance.
- Remove radiator cooling fan and fan shroud. See 170 Radi-
ator and Cooling System.
NOTE-
The radiator cooling fan nut (32 mm wrench) has left-hand
threads.
- Unbolt power steering fluid reservoir and bracket. Suspend to
one side without detaching fluid hoses.
- Disconnect alternator air cooling tube.
- Disconnect wiring from rear of alternator.
'4 Remove upper and lower mounting bolts (arrows) and lift
alternator.
If idler pulley for belt interferes, remove pulley cover and
retaining bolt to remove pulley. out

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-
Fuel Injection
of diagnostic time and to help avoid incorrect component re-
placement and possible damage to system components.
NOTE-
* Professional diagnostic scan tools available at the time of
this printing include the BMW factory tools and a small
number of aftermarket BMW-specific tools. The
CS2000
from Baum Tools Unlimited, the Retriever from Assenma-
chef Specialty Tools, and the MT2500 from Snap-on are
three examples.
In addition to the BMW-specific professional line of scan
tools, there are inexpensive generic OBD
I1 scan tool soft-
ware programs and
handheld units available. Although
these tools have limited capabilities as compared to the
dedicated tools, they are powerful diagnostic tools.
For the
DIY owner, simple aftermarltet DTC readeris avail-
able through
http://www.pealteresearch.com. This tool is
capable of checlting for
DTCs as well as turning off the il-
luminated
MIL and resetting the service indicator lights.
Tools and test equipment
If the equipment required to do the job is unavailable, it is rec-
ommended that these repairs be left to an authorized
BMW
dealer or other qualified BMW repair facility.
4 Low current test light ("noid")
(Tool No. Baum 11 15a)

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Fuel Injection
Warnings and cautions
For personal safety, as well as the protection of sensitive
electronic components, adhere to the warnings and cautions
on the following pages.
WARNING-
Gasoline is highly flammable and its vapors are explosive.
Do not smoke or work on a car near heaters or other fire
hazards when diagnosing and repairing fuel system prob-
lems. Have a fire extinguisher available in case of an emer-
gency
Renew fuel system hoses, clamps and O-rings any
time they are removed.
When working on an open fuel system, wear suitable
hand protection, as prolonged contact
with fuel can
cause illnesses and skin disorders.
* 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.
CAUTION-
- Disconnecting the battery may erase fault code($ storedin
memory Check for fault codes prior to disconnecting the
battery cables. Read the battery disconnection cautions in
001 General Warnings and Cautions.
a Connect and disconnect the DME system wiring and
1 test equipment leads only when the ignition is switched
off.
Wait at least 1 minute after turning off the ignition be-
fore removing the engine control module (ECM) con-
nector. If the connector is removed before this time,
residualpower in the system relay may damage the
control module.
Fuel system cleaners and other chemical additives oth-
er than those specifically recommended by BMW may
damage the catalytic converter, the oxygen sensor or
other fuel supply components.
* Do not connect any test equipment that delivers a 12-
volt power supply to terminal 15 (+) of the ignition coil.
The current flow may damage the ECM. In general,
connect test equipment only as specified by BMW or
the equipment maker.
Only use a digital
multirneter for electrical tests. Only
use an LED test light for
quiclc tests.