BMW 528i 1998 E39 Workshop Manual

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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.

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Battery, Starter, ~lternatorl
WARNING-
Always wear protective goggles and clothing when perform-
ing a load test.
Table
d. Battery load test - minimum voltage
Ambient temperature Voltage*
27
" C (80" F) 9.6 V
-I 8' C (0"
F) 8.5 V
* Measure
after applying a 200 amp load for 15 seconds.
Closed-circuit current measurement
If the vehicle battery is discharged for an unknown reason,
perform a closed-circuit current measurement as the first test.
For diagnostic purposes, it is important to not disconnect the
battery. Disconnecting the battery may reset a faulty control
unit, preventing proper diagnosis.
The following test is generally completed overnight using a
multimeterwith a closed circuitcurrent measurement adaptor
with a recording function
- Check that battery voltage is 12 volts or higher. If lower,
recharge battery.
- Switch off electrical consumers (interior lights, telephone,
aftermarket equipment, or others).
- Open luggage compartment and remove battery trim panel.
Use screwdriver to lock latch on trunk lid or hatch, simulating
closed luggage compartment. Close other doors.
- Open driver's door, then close it, simulating driver entering
vehicle.
- Switch ignition to RUN position for at least five seconds, then
turn ignition to OFF position. This simulates driving vehicle.
- Open and close driver's door, simulating driver leaving
vehicle.
- Lock car and arm alarm.
- Wait at least 16 minutes for consumer cut-off.

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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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121-9
Battery, Starter, ~lternatorl
Battery charging
Discharged batteries can be recharged using a batterycharg-
er. Remove the battery from the trunk during charging.
Prolonged charging causes electrolyte evaporation to a level
that can damage the battery. It is best to use a low-current
charger
(6 amperes or less) to prevent battery damage
caused by overheating.
WARNING -
Hydrogen gas given off by the battery during charging is ex-
plosive. Do not smoke.
Keep open flames away from the top
ofthe batte~ and prevent electrical sparks by turning off the
battery charger before connecting or disconnecting it.
Battery electrolyte (sulfuric acid) can damage the car. If
electrolyte is spilled, clean the area with a solution
ofbak-
ing soda and water.
Always allow a frozen battery to thaw before attempting
to recharge it.
Always disconnect both battery cables and remove bat-
tery from vehicle during battery charging. Do not ex-
ceed
16.5 charging voltage at the battery
Battery safety terminal, replacing
If the battery safety terminal has been triggered, investigate
and correct the cause prior to replacement.
- Working in right side of luggage compartment, remove bat-
tery trim panel.
- Disconnect negative (-) battery terminal and cover with
insulator.
- Disconnect positive (+) cable from battery.
- Release positive (+) cable from cable brackets on luggage
compartment wall. Lay new repair cable parallel to positive
cable.
- Mark off length of new cable on old cable. Allow 10 cm
(2.5 in) of slack.
- Saw through old cable.
Do not use bolt cutters or similar tools to cut through cable.
A cable end that has been squashed
flat will not fit into the

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121-10
I Battery, Starter, Alternator
- Strip approximately 15 rnm (0.6 in) of insulation from cable
end.
terminal harness
Shrink insulation
Terminal connector
4 Push terminal connector of new cable over stripped end of
old cable. Tighten clamp.
- Slip shrink-fit insulation over positive cable. Attach new safe-
ty harness to end of positive cable. Shrink insulation with hot
air blower.
- Reinstall cable in cable bracket and attach to battery.
- Reattach negative battery cable. Reinstall luggage cornpart-
rnent trim pieces.
- Use BMW scan tool DlSplus or equivalent to read out airbag
control module fault memory. Correct faults, then clear mem-
ory.
1 1 4 Various versions of alternators have been used in E39
vehicles. See Table e.
Table e. Alternator application chart
Model Alternator type
Air cooled, 90 amp or 120 amp
Air cooled, with multi-function control
(MFR), 120 amp or 140 amp
Air cooled with multi-function control
(MFR), 120 amp or 140 amp
540i 1997 Air
cooled. 120
amp or 140amp sazrz~orsl 1998 ~~~ ~ .~ . ...~ ~ ~-~~~~ Air cooled; with integrated mu~ii-
function control (MFR). 120 amp 140
amp 1999-2002 Water
cooled, with integrated multi-
function control (MFR), 90-150 amp
(variable output)

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121-11
Battery, Starter, ~lternatorl
Alternator 1997 - 98 5281 1997 540i
/-- -----,
I'
-----------
F15 / 7.5A/ :
&.. .... , 30 1 Xi0015
Battery
Hol in run 61 E (D+) Alternator
and stsrt
lBL
(Generator)
1 .--------,charge , . I , indicator I xGoli i
I <"9,7,a,T
Alternator, basic
On 1997-1 998 6-cylinderand 1997 V-8 models, the charging
system indicator light is supplied voltage
(+) to one side of the
light bulb, and the other side of the bulb is connected to the
voltage regulator.
With the engine off and the key in the run position, voltage
from the ignition switch flows through the regulator to ground,
completing the circuit and illuminating the charge indicator
bulb.
When the vehicle is started and the alternator begins to pro-
duce voltage, the output of the diode trio increases and the
light is turned off.
Alternator with multi-function control
(MFR)
Alternator with multi-function control
(MFR)
The multi-function controlled alternator is used on:
* 1999-2002 6-cylinder models
* 1998-2002 V-8 models
4 On cars with multi-function control alternator, the charge in-
dicator lamp is activated by means of an electronic switch in-
tegrated in the alternator controller. This switch receives its
voltage supply from terminal
15 on the 3-pin connector at the
rear of the alternator. The controller measures internally the
voltage difference between terminal 30 and terminal
15 and
signals the DME ECM to turn the charge indicator lamp on.
The controller features integrated fault detection. The battery
charge indicator lamp will come on in the event of:
* Failure of belt drive
No charge due to an
electrical/electronic fault
Interruption in excitation circuit
Over-voltage due to a defective controller output stage Fault or break in charge line
No charge due to alternator fault

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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
Charging system quick-check
Use a digital multimeter to measure voltage across the bat-
tery terminals with key off and then again with engine running.
Battery voltage should be about 12.6 volts with key off and be-
tween 13.5 and 14.5 volts with engine running.
NOTE-
The regulated voltage (engine running) should be between
13.2 and 14.5, depending on temperature andoperating con-
ditions.
If the voltage is higher than 14.8, the voltage regula-
tor or
mulitfunction controller is most likely faulty
Check for clean and tight battery cables. Check ground cable
running from negative
(-) battery terminal to chassis and
ground cable running from engine to chassis. Check alterna-
tor drive belt condition and tension.
Charging system, checking
CAUTIOI\C
* Do not disconnect the battery while the engine is running.
Damage to the alternator and/or engine electronic systems
may result.
Only use a digital multimeter when testing charging
system components.
--7
4 Turn ignition key on. Check that battery warning light comes
on.
NOTE-
If the warning light does not come on, repair bulb or wiring
faults before continuing to checlc the charging system.
/ Charge indicator
502820805
4 6-cylinder engines only, 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 lift air filter housing out of engine bay.

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- -
/Battery, Starter, Alternator -- - -. - --I
< Check for battery voltage at alternator terminal 30 (B+) (ar-
row):
Pull back rubber insulating cover at terminal 30 at rear of
alternator.
Connect voltmeter between terminal 30 and ground and
check for battery voltage.
If voltage is not present, check
wiring for faults.
NOTE-
On V-8 engines, access to the rear of the alternator is limited.
Check for battery voltage between the jump start post on the
left cylinder head and ground.
r Disconnect harness connector from alternator. Turn ianition
on and check for battery voltage between terminal
lgand
ground. If voltage is not present, check wiring and fuses for
faults.
Reconnect connector to alternator.
Locate the blue wire coming from terminal
61E of the alter-
nator connector. Carefully connect the positive
(+) test lead
to the wire using a piercing test lead end.
Turn ignition key on and check for voltage. Voltage should be
less than 1.5 VDC and charge indicator lamp should light.
- Making sure all test equipment and tools are clear, start en-
gine. Voltage should increase to
8.0 VDC or higher. The
charge indicator light should go out.
If voltage does not increase and system is not charging,
the fault is in alternator.
- If voltage does not increase, but system is charging, inter- - roaate svstem for faults usina an appropriate BMW scan - .. . tool and'reset fault memory.
- If a load tester is not available, a quick alternator output test
can be done by running engine at about 2000 rpm and turn-
- -
ing on electrical loads (fans, lights, rear window defroster, -
- and wipers). With all accessories on, battery voltage should
be above 12.6
V.