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001 General Warnings and Cautions
PLEASE READ THESE WARNINGS AND CAUTIONS
BEFORE PROCEEDING
WITH MAINTENANCE AND REPAIR WORK.
WARNINGS-
See also CAUTIONS
- Some repairs may be beyond your capability. If you lack the skills, - Catch draining fuel, oil, or brake fluid in suitable containers. Do
tools and equipment, or a suitable workplace for any procedure
not use
foodor beverage containers that might mislead someone
described in this manual, we suggest you leave such repairs to
into
drinking from them. Store flammable fluids away from fire
an authorized BMW dealer service department or other qualified
hazards. Wipe up spills at once, but do not store the oily rags,
shop. which can ignite and burn spontaneously.
. Do not reuse any fasteners that are worn or deformed. Many fas- Always observe good worRshop practices. Wear qoqqles when
teners are designed to be used only once and become
unreliable you operate machine tools or work with battery acid:kloves or
and mav fail when used a second time. This includes, but is not other
~rotective clothino should be worn whenever the iob re-
limited io, nuts, bolts, washers, self-locking nuts or bolts, clrclips yires' working with harmful substances.
and cotter pins. Always replace these fasteners with new parts.
Greases, lubricants and other automotive chemicals contain toxic
. Never work under a lifted car unless it is solidly supported on
substances, many of which are absorbed directly through the
stands
desiqned for the purpose. Do not supeort a car on cinder
skin. Read the manufacturer's instructions and warninos careful-
blochs, hollow tiles orotherbrops that may drurnbie undercontin-
uous toad. Never work under a car that is supported solely by a
iack. Never work under the car
while the enqine is runninq. - -
If you aregoing to work underacaron the ground, makesure that
the ground is level. Block the wheels to
keep the car from rolling.
Disconnect the battery negative
(-) terminal to prevent others
from starting the car while you are under it.
- Never run the engine unless the work area is well ventilated. Car-
bon monoxide kills.
Rings, bracelets and other jewelry should be removed so that
they cannot cause electrical shorts, get caught in running ma-
chinery, or be crushed by heavy parts.
- Tie long hair behind your head. Do not wear a necktie, a scarf.
loose clothing, or a necklace when you work near machine tools
or running engines. if your hair, clothing, or jewelry were to get
caught in the machinery, severe injury could result.
DO not attempt to
work on your car if you do not feel well. You in-
crease the
danger of injuryto yourseliand others if you are tired,
uDset or have taken medication or anv other substance that mav
keep you from being fully alert.
Illuminate your work area adequately but safely. Use a portable
iy. Use hand and eye protection. Avoid direct skin conGct.
Disconnect the battery negative (-) terminal whenever you work
on the fuel system
orthe electrical system. Do not smokeorwork
near heaters or other fire hazards. Keep an approved fire extin-
guisher handy.
. Friction materials (such as brake pads or shoes or clutch discs)
contain asbestos fibers or other friction materials. Do not create
dust by grinding, sanding, or by cleaning with compressed air.
Avoid breathing dust. Breathing any
friclion material dust can
lead to serious diseases and may result in death.
Batteries
giveoff explosive hydrogen gas during charging. Keep
sparks, lighted matches and open flame away from the top of the
battery. If hydrogen gas escaping from the cap vents is ignited, it
will ignite gas trapped in the cells and cause the battery to ex-
plode.
Connect and disconnect battery cables, jumper cables or a bat-
tery charger only wilh the ignition switched off. Do not disconnect
the battery while the engine is running.
Do not quick-charge the battery (for boost starting) for longer
than one minute. Wait at least one minute before boosting the
battery a second time.
. . safety lighiforworking lnsideor under the car. Make sure the bulb - Do not allow battery charging vollage to exceed 16.5 volts. If the
is enclosed bv a wire caoe. The hot filament of an accidentallv
batten! beoins ~roducina oas or boilino violentiv, reduce the
broken bulb can ignite spilled
fuel, vapors or oil. , - - - charglng rate. ~oostlng a sutfaled battery at a igh charging rate
can cause an
explosion.
-
Continued on next page
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.
General
WARNING-
Never run the engine in tile work area unless it is well-ven-
tilated. The exhaust should be vented to the outside. Car-
bon monoxide (CO) in exhaust kills.
Remove all neckties,
scarfs, loose clothing, or jewelry
when working near a running engine or power tools.
Tuck in shirts. Tie long hair and secure it under a cap.
Severe injury can result from these things being
caugiit
in rotating parts.
Remove rings, watches, and bracelets. Aside from the
dangers of moving parts, metallic jewelry conducts
electricity and may cause shorts, sparks, burns, or
damage to the electricalsystem when accidentally con-
tacting the battery or other electrical terminals.
Disconnect the battery negative
(-) cable whenever
working on or near the fuel system or anything that is
electrically powered. Accidental electrical contact may
damage the electrical system or cause a fire.
Fuelis highly flammable. When working around fuel, do
not
smoke or work near heaters or other fire hazards.
Keep an approved fire extinguisher handy.
The fuel system is designed to retain pressure even
when the ignition is off When worlcing with the
fuelsys-
tem, loosen the fuel lines slowly to allow the residual
pressure to dissipate gradually. Take precautions to
avoid spraying fuel.
. Illuminate the worlc area adequately and safely Use a
portable safety light for worlcing inside or under the car.
A fluorescent type
light is best because it gives off less
heat. If using a light with a normal incandescent bulb,
use rough service bulbs to avoid
breakage. The hot fil-
ament of an accidentally broken bulb can ignite spilled
fuel or oil.
Keep sparks, lighted matches, and any open flame
away from the top of the battery. Hydrogen gas
emitted
by the battery is highly flammable. Any nearby source
of ignition may cause the battery to explode.
Never lay
tools or parts in the engine compartment or
on top of the battery. They may
fallinto confinedspaces
and be difficult to retrieve, become caught in belts or
other rotating parts when the engine is started, or
cause electrical shorts and damage to the electrical
system.
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01 0-1 0
General
Electrical testing
Many electrical problems can be understood and solved with
only a little fundamental knowledge of how electrical circuits
function.
Electrical current
only flows in a complete circuit. To operate.
every electrical device in the car requires a complete circuit
including a voltage source and a path to ground. The positive
(+) side of the battery is the original voltage source, and
ground is any return path to the negative
(-) side of the bat-
tery, whether through the wiring harness or the car body. Ex-
cept for portions of the charging system, all electrical current
in the car is direct current (DC) and flows from positive
(+) to
negative
(-).
4 Switches are used to turn components on or off by complet-
ing or interrupting the circuit.
A switch is "open" when the cir-
cuit is interrupted, and "closed" when the circuit is completed.
See
600 Electrical System-General for electrical trouble-
(LW, 1 shooting
Wire repairs
Light bulb
(consumer) ' - Repairs to a wiring harness require special care to make the
repair permanent. The wire ends must be clean.
if frayed or
Car body otherwise damaged, cut off the end and remove enough insu- (ground) i Battery lation to complete the repair. if the wire is too short, splice in a BOZLiEL new piece of wire of the same size and make two connec-
tions.
Use connectors that are designed for the purpose. Crimped
on orsoldered-on connectors are best. Crimp connectors and
special crimping pliers are widely available. If soldering, use
needle nose pliers to hold the wire near the solder joint and
create a "heat dam". This keeps the heat and the solder from
traveling up the wire. Always use a solder made specifically
for electrical
work (rosin core).
NOJE-
Twisting wires together to make a repair is not recommend-
ed. Corrosion and vibration will eventually spoil the connec-
tion and may lead to irreparable damage to sensitive
electronic components.
Insulate the finished connection. Electronics stores can sup-
ply heat-shrinkable insulating tubing that can be placed on to
the wire before connecting, slid over the finished joint, and
shrunic to a tight fit with a heat gun or hair dryer. The next best
alternative is electrical tape. Make sure the wire is clean and
free of
solder flux or other contamination. Wrap the joint tight-
ly to seal out moisture. See
600 Electrical System-General
for more information.
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General
Torque wrench
A torque wrench is used to precisely tighten threaded fasten-
ers to a predetermined value. Many of the repair procedures
in this manual include BMW-specified torque values
in New-
ton-meters (Nm) and the equivalent values in foot-pounds
(ft-
Ib).
4 Several types of torque wrenches are available. An inexpen-
sive beam-type (top) is adequate but must be read visually. A
ratchet-type (bottom) can be preset to indicate (click) when
the torque value has been reached. They all do the same job,
but offer different convenience features at different prices.
The most convenient ones have a built-in ratchet, and can be
preset to indicate when a specific torque value has been
reached. Follow the wrench manufacturer's directions
for use
to achieve the greatest accuracy.
A torque wrench with a range up to about 150 Nm (1 10 ft-lb) BOIBFNG has adequate capacity for most of the repairs covered in this
manual. For recommended torque values of
10 Nm orbelow,
the English system equivalent is given in inch-pounds (in-lb).
These small values may be most easily reached using a
torque wrench calibrated in inch-pounds. To convert
inch-
pounds to foot-pounds, divide by 12.
Digital multimeter
4 Many of the electrical tests in this manual call for the mea-
surement of resistance (ohms) or voltage values. For safe
and accurate tests of sensitive electronic component and
systems, a multimeter or digital
volt/ohm meter (DVOM) with
high input impedance (at least
10,000Sr) should be used.
Some meters have automotive functions such as dwell and
pulse width that are useful for troubleshooting ignition and
fuel injection problems.
CAUTIOI\C
Vehicle electronic systems may be damaged by the high cur-
rent draw of a test light with a normal incandescent bulb. As
a general rule, use a high impedance digital multimeter or an
LED test light for all electrical testing.
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Spare parts kit
Carrying a basic set of spare parts can prevent a rninorbreak-
down from turning into a major repair annoyance. The list be-
low is a good place to start.
Spare parts kit
- basic
Polyribbed drive
belt(s)
BMW engine oil: one or two quarts
BMW engine coolant:
1 gallon of premixed 50150 BMW
anti-freeze and water
Fuse assortment:
7.5A. IOA, 1 5A, 20A, 30A. 50A
Radiator hoses: upper and lower
Spare parts
kit - additional contents
Exterior lighting bulbs: headlight, bralte light, turn signal,
and taillight
* Wiper blades or blade inserts
Brake fluid: new, unopened bottle, DOT
4 specification
Main relay for DME system
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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, ~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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Fuel Tank and Fuel Pump
Warnings and cautions
Observe the following warnings and cautions when servicing
the fuel system.
WARNING-
* The fuel system is designed to retain pressure even when
the ignition is off. When working with the fuelsystem, loos-
en the fuel lines slowly to allow residual
fuel pressure to
dissipate. Avoid spraying fuel. Use shop rags to capture
leaking fuel.
Before beginning any work on the fuel system, place a
fire extinguisher in the vicinity of the work area.
Fuel is highly flammable. When working around fuel, do
not disconnect any wires that could cause electrical
sparks. Do not smoke or worknearheaters or other fire
hazards.
* Always unscrew the fuel tank cap to release pressure
in the
tanlc before working on the tank or lines.
When disconnecting a fuel hose, wrap shop rag around
end of hose to prevent spray of fuel under pressure.
Do not use a work light with an incandescent bulb near
any fuel. Fuel may spray on the hot bulb causing a fire.
0 Make sure the worlc area is properly ventilated.
CAUTION-
- Prior to disconnecting the battery, read the battery discon-
nection cautions given in
001 General Cautions an4
Warnings.
Before
making any electrical tests with the ignition
turned on, disable the ignition system as described in
120 Ignition System. Be sure the battery is discon-
nected when replacing components.
To prevent damage to the ignition system or other DME
components, including the engine control module
(ECM), always connect and disconnect wires and test
equipment with the ignition off.
Cleanliness is essential when
worl~ing with the fuel sys-
tem. Thoroughly clean the fuel line unions before dis-
connecting any of the lines.
Use only clean tools. Keep removed parts clean and
sealed or covered with a clean, lint-free cloth, especial-
ly if completion of the repair is delayed.
Do not move the car while the fuel system is open.
Avoid using high pressure compressed air to blow out
lines and components. High pressure can rupture inter-
nal seals and gaskets.
Always replace seals, O-rings and hose clamps.