battery type BMW 3 SERIES 1985 E30 Owner's Manual

connect the ohmmeter to coil terminal 1 (-)
and the centre tower. On Motronic systems,
connect the ohmmeter to coil terminal 15 (+)
and the centre tower. Compare the measured
resistance with the values given in the Specifi-
cations in this Chapter.
6If the measured resistances are not close to
those specified, the coil is defective and
should be renewed. Note that the measured
resistance will vary according to the
temperature of the coil, so don’t rush to
condemn the coil if the resistance is only a
little way out.
7It is essential for proper ignition system
operation that all coil terminals and wire leads
be kept clean and dry.
8Refit the coil in its mounting, and reconnect
the wiring. Refitting is the reverse of removal.
10 Impulse generator and
ignition control unit- check
and renewal (TCI system)
3
1The impulse generator (located in the
distributor) and ignition control unit need to be
tested in the event there is no spark at the
spark plugs. Make sure the plug leads,
ignition coil and spark plugs are working
properly (see Sections 6 and 9). There are two
types of control units; Bosch or
Siemens/Telefunken. The two types (see
illustration)can be distinguished by their
electrical connectors. The Bosch type uses a
single, large rectangular connector at the
bottom of the unit, while the
Siemens/Telefunken control unit uses two
round electrical connectors at the front of the
unit.
Check
Voltage supply and earth to ignition
control unit
2With the ignition off, remove the harness
connectors from the ignition control unit (see
illustrations). Connect a voltmeter between
connector terminals 2 and 4 on Bosch
systems, or between terminals 6 and 3 on
Siemens/Telefunken systems.
3Turn the ignition on. There should be
battery voltage on the designated terminals. If
there is no voltage, check the wiring harness
for an open-circuit (see Chapter 12).
4Using an ohmmeter, check for continuity
between connector terminal 2 (Bosch) or 6
(Siemens/Telefunken) and the earth to the
vehicle body. Continuity should exist.
5Using an ohmmeter, check for continuity
between connector terminal 4 (Bosch) or 3
(Siemens/Telefunken) and terminal 15 of the
ignition coil. Continuity should exist.
6If the readings are incorrect, repair the
wiring harness.
Impulse generator signal
7If the ignition control unit is receiving
battery voltage, check the A/C signal voltage
coming from the impulse generator to the
control unit.
5•6 Engine electrical systems
10.2b Check for voltage at terminals 6 and
3 on the control unit electrical connector
(Siemens/Telefunken system shown)10.2a Check for voltage at terminals 2 and
4 on the control unit electrical connector
(Bosch system shown)
1 Coil HT lead
2 Ignition coil
3 Spark plug HT lead
4 Spark plug
5 Ignition control unit (Bosch)
6 Ignition control unit
(Siemens/Telefunken)
7 Wiring harness8 Distributor housing with
centrifugal advance
counterweights
9 Vacuum diaphragm
10 Circlip
11 Impulse generator
12 Trigger wheel
13 Circlip
14 Dust shield15 Ignition rotor
16 Distributor
17 Roll pin
18 Trigger wheel and impulse
generator tabs
19 Cap retaining clip
20 Impulse generator
connector
10.1 Schematic of the ignition components used on engines with the TCI system

Withdraw the sensor from its bracket and
remove it.
11When fitting the new sensor, use a brass
feeler gauge to position the tip of the sensor
the correct distance from the pulse wheel
(see illustration).
12Tighten the mounting bolt, but be careful
not to overtighten it.
13 Charging system- general
information and precautions
There are two different types of alternator
fitted on these models; Bosch and Motorola.
Also, there are three different amperage
ratings available; 65A, 80A or 90A. A stamped
serial number on the rear of the alternator will
identify the type and amperage rating.
Perform the charging system checks (see
Section 14) to diagnose any problems with the
alternator.
The voltage regulator and the alternator
brushes are mounted as a single assembly.
On Bosch alternators, this unit can be
removed from the alternator (see Section 16)
and the components serviced individually.
The alternator on all models is mounted on
the left front of the engine, and utilises a V-
belt and pulley drive system. Drivebelt tension
and battery servicing are the two primary
maintenance requirements for these systems.
See Chapter 1 for the procedures regarding
engine drivebelt checking and battery
servicing.
The ignition/no-charge warning light should
come on when the ignition key is turned to
Start, then go off immediately the engine
starts. If it remains on, there is a malfunction
in the charging system (see Section 14). Some
vehicles are also equipped with a voltmeter. If
the voltmeter indicates abnormally high or low
voltage, check the charging system (see
Section 14). Note:On models up to 1986, a
blown ignition/no-charge warning light will
prevent the alternator from charging. After
1987, a resistor is wired in parallel with the
warning light in order to allow current tobypass the light in the event of a broken circuit
(blown warning light).
Precautions
Be very careful when making electrical
circuit connections to the alternator, and note
the following:
a) When reconnecting wires to the alternator
from the battery, be sure to note the
polarity.
b) Before using arc-welding equipment to
repair any part of the vehicle, disconnect
the wires from the battery terminals and
from the alternator.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
c) Never start the engine with a battery
charger connected. Always disconnect
both battery cables before using a battery
charger.
d) Never disconnect cables from the battery
or from the alternator while the engine is
running.
e) The alternator is turned by an engine
drivebelt. Serious injury could result if
your hands, hair or clothes become
entangled in the belt with the engine
running.
f) Because the alternator is connected
directly to the battery, take care not to
short out the main terminal to earth.
g) Wrap a plastic bag over the alternator,
and secure it with rubber bands, before
steam-cleaning the engine.
14 Charging system- check
3
1If a malfunction occurs in the charging
circuit, don’t automatically assume that the
alternator is causing the problem. First check
the following items:
a) Check the drivebelt tension and condition
(see Chapter 1). Renew the drivebelt if it’s
worn or deteriorated.
b) Make sure the alternator mounting and
adjustment bolts are tight.
c) Inspect the alternator wiring harness and
the connectors at the alternator and
voltage regulator. They must be in good
condition and tight.
d) Check the fuses.
e) Start the engine and check the alternator
for abnormal noises (a shrieking or
squealing sound indicates a worn bearing,
but could also be due to a slipping
drivebelt - see a) above).f) Check the specific gravity of the battery
electrolyte. If it’s low, charge the battery
(doesn’t apply to maintenance-free
batteries).
g) Make sure the battery is fully-charged
(one bad cell in a battery can cause
overcharging by the alternator).
h) Disconnect the battery cables (negative
first, then positive). Inspect the battery
posts and the cable clamps for corrosion.
Clean them thoroughly if necessary (see
Chapter 1).
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
2With the ignition off, connect a 12 volt test
light between the battery negative post and
the disconnected negative cable clamp. If the
test light does not come on, refit the cable
and proceed to paragraph 4. If the test light
comes on, there is a short (drain) in the
electrical system of the vehicle. The short
must be repaired before the charging system
can be checked. Note: Accessories which are
always on (such as the clock or the radio
station memory) must be disconnected before
performing this check.
3Disconnect the alternator wiring harness. If
the test light now goes out, the alternator is
faulty. If the light stays on, remove each fuse
in turn until the light goes out (this will tell you
which component is shorting out).
4Using a voltmeter, check the battery
voltage with the engine off. It should be
approximately 12 volts.
5Start the engine and check the battery
voltage again. It should now be approximately
14 to 15 volts.
6Turn on the headlights. The voltage should
drop, and then come back up, if the charging
system is working properly.
7If the voltage reading is more than the
specified charging voltage, renew the voltage
regulator (refer to Section 16). If the voltage is
less, the alternator diode(s), stator or rotor
may be faulty, or the voltage regulator may be
malfunctioning.
8If there is no short-circuit causing battery
drain but the battery is constantly
discharging, then either the battery itself is
defective, the alternator drivebelt is loose (see
Chapter 1), the alternator brushes are worn,
dirty or disconnected (see Section 17), the
voltage regulator is malfunctioning (see
Section 16) or the diodes, stator coil or rotor
coil are defective. Repairing or renewing the
diodes, stator coil or rotor coil is beyond the
scope of the home mechanic. Either renew
Engine electrical systems 5•9
12.11 The sensor tip should be set at 1.0 ±
0.3 mm from the pulse wheel
5

the alternator complete, or take it to an
automotive electrician, who may be able to
overhaul it. Note:On models up to 1986, a
blown ignition/no-charge warning light bulb
will prevent the alternator from charging. After
1987, a resistor is wired in parallel with the
warning light, in order to allow current to
bypass the light in the event of a broken circuit
(blown warning light).
15 Alternator-
removal and refitting
1
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Removal
1Detach the battery negative cable.2Detach the electrical connectors from the
alternator, noting their locations for refitting
(see illustration). Note: On some models, it
may be necessary to remove the air cleaner
assembly and airflow meter to gain access to
the alternator.
3Loosen the alternator adjustment and pivot
bolts, and slip off the drivebelt (see Chap-
ter 1).
4Remove the adjustment and pivot bolts,
and separate the alternator from the engine.
Refitting
5If you are renewing the alternator, take the
old one with you when purchasing a new or
reconditioned unit. Make sure the new unit
looks identical to the old alternator. Look at
the terminals - they should be the same in
number, size and location as the terminals on
the old alternator. Finally, look at the identifi-
cation numbers - they will be stamped into the
housing, or printed on a tag attached to the
housing. Make sure the numbers are the same
on both alternators.
6Many new alternators do not come with a
pulley fitted, so you may have to transfer the
pulley from the old unit to the new one.
7Refitting is the reverse of removal.
8After the alternator is fitted, adjust the
drivebelt tension (see Chapter 1).
9Check the charging voltage to verify
proper operation of the alternator (see Sec-
tion 14).
16 Voltage regulator- renewal
1
1The voltage regulator controls the charging
system voltage by limiting the alternator
output. The regulator is a sealed unit, and isn’t
adjustable.
2If the voltmeter indicates that the alternator
is not charging (or if the ignition/no-charge
warning light comes on) and the alternator,
battery, drivebelt tension and electrical
connections seem to be fine, have theregulator checked by a dealer service
department or electrical specialist.
3Disconnect the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Bosch alternator
4The voltage regulator is mounted externally
on the alternator housing. To renew the
regulator, remove the mounting screws (see
illustration)and lift it off the alternator (see
illustration). Note: Some Bosch alternators
have an integral voltage regulator which is part
of the brush assembly.
5Refitting is the reverse of removal. Note:
Before refitting the regulator, check the
condition of the slip rings(see illustration).
Use a torch and check for any scoring or deep
wear grooves. Renew the alternator if
necessary.
Motorola alternator
6Remove the alternator from the engine
compartment (see Section 15).
7Remove the rear cover and diode carrier,
remove the voltage regulator mounting
screws (see illustration)and lift the regulator
off the alternator body.
8Refitting is the reverse of removal.
17 Alternator brushes-
check and renewal
3
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery.
5•10 Engine electrical systems
16.5 Use a torch to check the slip rings for
scoring or deep grooves16.4b The regulator can be withdrawn
easily on Bosch alternators. This type of
regulator is integral with the brush
assembly16.4a Remove the nuts and lift off the
small terminal protector from the
alternator cover, then remove the nuts and
the cover
15.2 Depending on how many accessories
the vehicle has, sometimes it’s easier to
remove the alternator from the brackets
first, and then turn it sideways to gain
access to the connections (arrowed) on
the rear of the alternator body

Refer to the information on page 0-7 at the
front of this manual before detaching the
cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
1Disconnect the battery negative cable.
Bosch alternator
2Remove the voltage regulator from the back
of the alternator (see Section 16).
3Measure the length of the brushes (see
illustration). They should not be less than
6.0 mm. If any are worn past this point, renew
them all as a set. 4Also check for excessively worn slip rings
(see illustration 16.5).
5The brushes are retained either by set
screws or by solder. If you are not skilled at
soldering, it may be best to have an auto
electrician fit the new brushes. Note: Be
careful not to apply heat to the solder joint for
more than 5 seconds. If necessary, use a heat
sink to capture the excess heat. This can be
accomplished by clamping a pair of needle-
nose pliers next to the solder joint.
6On the screw type, hold the assembly in
place and refit the screws. Tighten them
evenly, a little at a time, so the holder isn’t
distorted.
7Refit the regulator assembly to the
alternator.8Reconnect the battery negative cable.
Motorola alternator
9Remove the alternator.
10The brushes are mounted under the
regulator on the rear of the alternator (see
illustration 16.7).
11Remove the mounting screws and
insulating washers, and separate the voltage
regulator and brush holder from the brush end
housing.
12Measure the length of the brushes (see
illustration 17.3). If any brush is less then
6.0 mm long, renew them all as a set.
13Make sure the brushes move smoothly in
the holder.
14Refit the brush holder/regulator. Tighten
the screws securely. Make sure the brushes
aren’t earthed.
15Refitting is the reverse of removal.
18 Starting system- general
information and precautions
The sole function of the starting system is
to turn over the engine quickly enough to
allow it to start.
The starting system consists of the battery,
the starter motor, the starter solenoid, the
ignition switch, and the wires connecting
them. The solenoid is mounted directly on the
starter motor. The starter/solenoid motor
assembly is fitted on the lower part of the
engine, next to the transmission bellhousing.
When the ignition key is turned to the Start
position, the starter solenoid is actuated
through the starter control circuit. The starter
solenoid then connects the battery to the
starter, and moves the starter pinion into
mesh with the flywheel ring gear. The battery
supplies the electrical energy to the starter
motor, which does the actual work of cranking
the engine.
The starter motor on some manual
transmission vehicles can only be operated
when the clutch pedal is depressed. On a
vehicle equipped with automatic
transmission, the starter can only be operated
Engine electrical systems 5•11
17.3 Check the brush length in the normal
rest position (spring uncoiled)
5
16.7 Exploded view of the Motorola alternator

Check
12Warm up the engine, and let it run at idle.
Disconnect the oxygen sensor electrical
connector, and connect the positive probe of
a voltmeter to the oxygen sensor output
connector terminal (refer to the following
table) and the negative probe to earth (see
illustrations).
Note:Most oxygen sensor electrical
connectors are located at the rear of the
engine, near the bulkhead. Look for a large
rubber boot attached to a thick wire harness.
On early 535i models, the connector for the
oxygen sensor heater circuit is under the
vehicle. Look for a small protective cover.
These models should have the updated
oxygen sensor fitted, to make access similar
to other models. Consult your dealer service
department for additional information.
13Increase and then decrease the engine
speed, and monitor the voltage.
14When the speed is increased, the voltage
should increase to 0.5 to 1.0 volts. When the
speed is decreased, the voltage should fall to
about 0 to 0.4 volts.
15Also where applicable, inspect the oxygen
sensor heater (models with multi-wire
sensors). With the ignition on, disconnect the
oxygen sensor electrical connector, and
connect a voltmeter across the terminals
designated in the chart (see below). There
should be battery voltage (approximately
12 volts).
16If the reading is not correct, check the
oxygen sensor heater relay (see Chapter 12).
If the information is not available, check the
owner’s handbook for the exact location of
the oxygen sensor heater relay. The relay
should receive battery voltage.
17If the oxygen sensor fails any of these
tests, renew it.
Renewal
Note: Because it is fitted in the exhaust
manifold, converter or pipe, which contracts
when cool, the oxygen sensor may be very
difficult to loosen when the engine is cold.
Rather than risk damage to the sensor(assuming you are planning to re-use it in
another manifold or pipe), start and run the
engine for a minute or two, then switch it off.
Be careful not to burn yourself during the
following procedure.
18Disconnect the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
19Raise and support the vehicle.
20Disconnect the electrical connector from
the sensor.
21Carefully unscrew the sensor.
Caution: Excessive force may
damage the threads.
22A high-temperature anti-seize compound
must be used on the threads of the sensor, to
facilitate future removal. The threads of new
sensors will already be coated with this
compound, but if an old sensor is removed
and refitted, recoat the threads.23Refit the sensor and tighten it securely.
24Reconnect the electrical connector of the
pigtail lead to the main engine wiring harness.
25Lower the vehicle, and reconnect the
battery.
Oxygen Sensor Heated power
sensor type output signal supply (12V)
Unheated
(single-wire) black wire (+) Not applicable
Heated terminal 1 (+) terminals
(three-wire) 3 (+) and 2 (-)
Heated terminal 2 (+) terminals
(four-wire) 4 (+) and 3 (-)
Throttle Position Sensor (TPS)
General description
26The Throttle Position Sensor (TPS) is
located on the end of the throttle shaft on the
throttle body. By monitoring the output
voltage from the TPS, the ECU can determine
fuel delivery based on throttle valve angle
(driver demand). In this system, the TPS acts
as a switch rather than a potentiometer. One
set of throttle valve switch contacts is closed
(continuity) only at idle. A second set of
contacts closes as the engine approaches
full-throttle. Both sets of contacts are open
(no continuity) between these positions. A
broken or loose TPS can cause intermittent
bursts of fuel from the injector and an
unstable idle, because the ECU thinks the
throttle is moving.
27All models (except for early 535i models
with automatic transmission) combine the idle
and full-throttle switch; a separate idle
position switch indicates the closed-throttle
position, while the TPS is used for the full-
throttle position. On 535i models with
automatic transmission, the TPS is connected
directly to the automatic transmission control
unit. With the throttle fully open, the
transmission control unit sends the full-
throttle signal to the Motronic control unit.
All models except early 535i with
automatic transmission
Check
28Remove the electrical connector from the
TPS, and connect an ohmmeter to terminals 2
and 18 (see illustrations). Open the throttle
Engine management and emission control systems 6•3
4.12b These oxygen sensor terminal
designations are for the harness side only.
Use the corresponding terminals on the
sensor side for the testing procedures
(there are three different four-wire oxygen
sensor connectors available - don’t get
them mixed up)4.12a The oxygen sensor, once it is
warmed up (320º C), puts out a very small
voltage signal. To verify it is working,
check for voltage with a digital voltmeter
(the voltage signals usually range from
0.1 to 1.0 volt)
4.28b First check for continuity between
terminals 2 and 18 with the throttle closed
(later Motronic system shown) . . .4.28a The TPS on L-Jetronic systems is
located under the intake manifold
(terminals arrowed)
6

filtered with a flame trap like most
conventional systems. There are no
conventional PCV valves fitted on these
systems - just a hose (see illustration).
3The main components of the PCV system
are the hoses that connect the valve cover to
the throttle body or air cleaner. If abnormal
operating conditions (such as piston ring
problems) arise, the system is designed to
allow excessive amounts of blow-by gases to
flow back through the crankcase vent tube
into the intake system, to be consumed by
normal combustion. Note: Since these
models don’t use a filtering element, it’s a
good idea to check the PCV system
passageways for clogging from sludge and
combustion residue(see illustration).
6 Evaporative emissions
control (EVAP) system
2
General description
Note:This system is normally only fitted to
those vehicles equipped with a catalytic
converter.
1When the engine isn’t running, the fuel in the
fuel tank evaporates to some extent, creating
fuel vapour. The evaporative emissions control
system (see illustration)stores these fuel
vapours in a charcoal canister. When the
engine is cruising, the purge control valve is
opened slightly, and a small amount of fuel
vapour is drawn into the intake manifold and
burned. When the engine is starting cold or
idling, the purge valve prevents any vapours
from entering the intake manifold and causing
excessively-rich fuel mixture.
2Two types of purge valve are used;
electrically-operated or vacuum-operated. To
find out which type is on your vehicle, follow
the hose from the charcoal canister until you
locate the purge valve. Some are located on
the intake manifold, and others near the
charcoal canister. Look for either an electrical
connector, or vacuum lines, to the purge
valve.3A faulty EVAP system will only affect engine
driveability when the engine is warm. The
EVAP system is not usually the cause of
difficult cold starting or any other cold-running
problems.
Check
Vacuum-operated purge valve
4Remove the vacuum lines from the purge
valve, and blow into the larger valve port. It
should be closed, and not pass any air. Note:
Some models have a thermo-vacuum valve
that delays canister purging until the coolant
temperature reaches approximately 46º C.
Check this valve to make sure that vacuum is
controlled at the proper temperatures. The
valve is usually located in the intake manifold,
near the thermo-time switch and the coolant
temperature sensor.
5Disconnect the small vacuum hose from the
purge valve, and apply vacuum with a hand-
held vacuum pump. The purge valve should
be open, and air should be able to pass
through.6If the test results are unsatisfactory, renew
the purge valve.
Electrically-operated purge valve
7Disconnect any lines from the purge valve,
and (without disconnecting the electrical
connector) place it in a convenient spot for
testing.
8Check that the valve makes a “click” sound
as the ignition is switched on (see
illustration).
9If the valve does not “click”, disconnect the
valve connector, and check for power to the
valve using a test light or a voltmeter (see
illustration).
10If battery voltage is present, but the valve
does not work, renew it. If there is no voltage
present, check the Motronic control unit and
the wiring.
Canister
11Mark all the hoses for position, then
detach them from the canister.
12Slide the canister out of its mounting clip.
Engine management and emission control systems 6•5
6.1 Diagram of the EVAP system on the M10 engine (others similar)
6.9 Check for battery voltage at the
electrical connector to the purge valve6.8 When the ignition is switched on, there
should be a distinct “click” from the purge
valve
6
5.3 It’s a good idea to check for excess
residue from the crankcase vapours
circulating in the hoses and ports - this
can eventually clog the system, and cause
a pressure increase in the engine block

Refitting
7Refitting is the reverse of removal. Tighten
the nuts and bolts securely. Adjust the
drivebelt tension (see Chapter 1).
8Top-up the fluid level in the reservoir (see
Chapter 1) and bleed the system (see Sec-
tion 23).
23 Power steering system-
bleeding
1
1To bleed the power steering system, begin
by checking the power steering fluid level and
adding fluid if necessary (see Chapter 1).
2Raise and support the front of the vehicle
on axle stands.
3Turn the steering wheel from lock-to-lock
several times. Recheck the fluid level and top
up if necessary.
4Start the engine and run it at 1000 rpm or
less. Turn the steering wheel from lock-to-
lock again (three or four times) and recheck
the fluid level one more time. Note:On 5-Series E28 (“old-shape”) models, pump the
brake pedal five or six times before turning the
steering wheel. Once the fluid level remains
constant, continue turning the wheel back and
forth until no more bubbles appear in the fluid
in the reservoir.
5Lower the vehicle to the ground. Run the
engine and again turn the wheels from lock-
to-lock several more times. Recheck the fluid
level. Position the wheels straight-ahead.24 Steering wheel-
removal and refitting
1
Warning: If the vehicle is
equipped with an airbag, do not
attempt this procedure. Have it
performed by a dealer service
department or other qualified specialist, as
there is a risk of injury if the airbag is
accidentally triggered.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you have
the correct activation code
before disconnecting the battery.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Removal
1Disconnect the battery negative cable.
2Using a small screwdriver, prise off the
BMW emblem in the centre of the steering
wheel.
3Remove the steering wheel nut, and mark
the relationship of the steering wheel hub to
the shaft (see illustration).
4On all 3-Series models, and on 1986 and
later 5-Series models, turn the ignition key to
the first position to unlock the ignition lock.
5Remove the steering wheel from thesteering shaft. If the wheel is difficult to
remove from the shaft, use a steering wheel
puller to remove it - don’t hammer on the
shaft.
Refitting
6Refitting is the reverse of removal. Be sure
to align the match marks you made on the
steering wheel and the shaft. Tighten the
steering wheel nut to the torque listed in this
Chapter’s Specifications.
25 Wheels and tyres-
general information
1
Note:For more information on care and
maintenance of tyres, refer to Chapter 1.
1All vehicles covered by this manual are
equipped with steel-belted radial tyres as
original equipment. Use of other types or
sizes of tyres may affect the ride and handling
of the vehicle. Don’t mix different types or
sizes of tyres, as the handling and braking
may be seriously affected. It’s recommended
that tyres be renewed in pairs on the same
axle; if only one new tyre is being fitted, be
sure it’s the same size, structure and tread
design as the other.
2Because tyre pressure has a substantial
effect on handling and wear, the pressure on
all tyres should be checked at least once a
month or before any extended trips (see
Chapter 1).
3Wheels must be renewed if they are bent,
heavily dented, leak air, or are otherwise
damaged.
4Tyre and wheel balance is important in the
overall handling, braking and performance of
the vehicle. Unbalanced wheels can adversely
affect handling and ride characteristics, as
well as tyre life. Whenever a new tyre is fitted,
the tyre and wheel should be balanced.
10•16 Suspension and steering systems
24.3 After removing the steering wheel
nut, mark the relationship of the steering
wheel to the steering shaft (arrowed) to
ensure proper alignment during
reassembly
22.6c Typical 5-Series power steering pump mounting bolts
(arrowed)22.6b . . . and mounting nut and bolt (arrowed)

12
Chapter 12 Body electrical systems
Bulb renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Central locking system - description and check . . . . . . . . . . . . . . . . 20
Cruise control system - description and check . . . . . . . . . . . . . . . . 19
Direction indicator/hazard warning flasher - check and renewal . . . 5
Electric windows - description and check . . . . . . . . . . . . . . . . . . . . 21
Electrical system fault finding - general information . . . . . . . . . . . . . 2
Fuses - general information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Headlight housing - removal and refitting . . . . . . . . . . . . . . . . . . . . . 14
Headlights - adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Headlights - bulb renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Heated rear window - check and repair . . . . . . . . . . . . . . . . . . . . . . 17
Ignition switch - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . 7
Instrument cluster - removal and refitting . . . . . . . . . . . . . . . . . . . . . 10
Radio - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Radio aerial - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Relays - general information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Service Indicator (SI) board - general information . . . . . . . . . . . . . . 11
Steering column switches - removal and refitting . . . . . . . . . . . . . . . 6
Supplemental Restraint System (SRS) - general information . . . . . . 18
Windscreen/tailgate wiper motor - removal and refitting . . . . . . . . . 16
Wiring diagrams - general information . . . . . . . . . . . . . . . . . . . . . . . 22
12•1
Easy,suitable for
novice with little
experienceFairly easy,suitable
for beginner with
some experienceFairly difficult,
suitable for competent
DIY mechanic
Difficult,suitable for
experienced DIY
mechanicVery difficult,
suitable for expert
DIY or professional
Degrees of difficulty Contents
1 General information
The chassis electrical system of this vehicle
is of 12-volt, negative earth type. Power for
the lights and all electrical accessories is
supplied by a lead/acid-type battery, which is
charged by the alternator.
This Chapter covers repair and service
procedures for various chassis (non-engine
related) electrical components. For
information regarding the engine electrical
system components (battery, alternator,
distributor and starter motor), see Chapter 5.
Warning: To prevent electrical
short-circuits, fires and injury,
always disconnect the battery
negative terminal before
checking, repairing or renewing electrical
components.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you have
the correct activation code
before disconnecting the battery, Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
2 Electrical system fault
finding- general information
2
A typical electrical circuit consists of an
electrical component, any switches, relays,
motors, fuses, fusible links or circuit breakers,
etc related to that component, and the wiring
and connectors that link the components to
both the battery and the chassis. To help you
pinpoint an electrical circuit problem, wiring
diagrams are included at the end of this book.
Before tackling any troublesome electrical
circuit, first study the appropriate wiring
diagrams to get a complete understanding of
what makes up that individual circuit.
Troublespots, for instance, can often be
isolated by noting if other components related
to that circuit are routed through the same
fuse and earth connections.
Electrical problems usually stem from
simple causes such as loose or corroded
connectors, a blown fuse, a melted fusible
link, or a bad relay. Inspect all fuses, wires
and connectors in a problem circuit first.
The basic tools needed include a circuit
tester, a high-impedance digital voltmeter, a
continuity tester and a jumper wire with an in-
line circuit breaker for bypassing electrical
components. Before attempting to locate or
define a problem with electrical testinstruments, use the wiring diagrams to
decide where to make the necessary
connections.
Voltage checks
Perform a voltage check first when a circuit
is not functioning properly. Connect one lead
of a circuit tester to either the negative battery
terminal or a known good earth.
Connect the other lead to a connector in
the circuit being tested, preferably nearest to
the battery or fuse. If the bulb of the tester
lights up, voltage is present, which means that
the part of the circuit between the connector
and the battery is problem-free. Continue
checking the rest of the circuit in the same
fashion.
When you reach a point at which no voltage
is present, the problem lies between that point
and the last test point with voltage. Most of
the time, problems can be traced to a loose
connection.Note:Keep in mind that some
circuits receive voltage only when the ignition
key is turned to a certain position.
Electrical fault diagnosis is simple if you
keep in mind that all electrical circuits are
basically electricity running from the battery,
through the wires, switches, relays, fuses and
fusible links to each electrical component
(light bulb, motor, etc) and then to earth, from
where it is passed back to the battery. Any
electrical problem is an interruption in the flow
of electricity to and from the battery.

Finding a short-circuit
One method of finding a short-circuit is to
remove the fuse and connect a test light or
voltmeter in its place. There should be no
voltage present in the circuit. Move the
electrical connectors from side-to-side while
watching the test light. If the bulb goes on,
there is a short to earth somewhere in that
area, probably where the insulation has been
rubbed through. The same test can be
performed on each component in a circuit,
even a switch.
Earth check
Perform a earth check to see whether a
component is properly earthed (passing
current back via the vehicle body). Disconnect
the battery, and connect one lead of a self-
powered test light (often known as a
continuity tester) to a known good earth.
Connect the other lead to the wire or earth
connection being tested. The bulb should
light, indicating a good earth connection. If
not, dismantle the connection, and clean all
relevant parts thoroughly. When re-making
the connection, use serrated (shakeproof)
washers if possible, and tighten all bolts, etc,
securely.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you have
the correct activation code
before disconnecting the battery, Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Continuity check
A continuity check determines if there are
any breaks in a circuit - if it is conducting
electricity properly. With the circuit off (no
power in the circuit), a self-powered continuity
tester can be used to check the circuit.
Connect the test leads to both ends of the
circuit, and if the test light comes on, the
circuit is passing current properly. If the light
doesn’t come on, there is a break somewhere
in the circuit. The same procedure can be
used to test a switch, by connecting the
continuity tester to the power-in and power-
out sides of the switch. With the switch turned
on, the test light should come on.
Finding an open-circuit
When diagnosing for possible open-
circuits, it is often difficult to locate them by
sight, because oxidation or terminal
misalignment are hidden by the connectors.
Intermittent problems are often caused by
oxidised or loose connections. Merely
wiggling an electrical connector may correct
the open-circuit condition, albeit temporarily.
Dismantle the connector, and spray with a
water-dispersant aerosol. On simpler
connectors, it may be possible to carefullybend the connector pins inside, to improve
the metal-to-metal contact - don’t damage
the connector in the process, however.
3 Fuses- general information
1
The electrical circuits of the vehicle are
protected by a combination of fuses and
circuit breakers. The fusebox is located in the
left corner of the engine compartment (see
illustration). On some later models, it is
located under the rear seat cushion.
Each of the fuses is designed to protect a
specific circuit, and on some models, the
various circuits are identified on the fuse
panel itself.
Miniaturised fuses are employed in the
fuseboxes. These compact fuses, with blade
terminal design, allow fingertip removal and
renewal. If an electrical component fails,
always check the fuse first. A blown fuse is
easily identified through the clear plastic
body. Visually inspect the element for
evidence of damage. If a continuity check is
called for, the blade terminal tips are exposed
in the fuse body.
Be sure to renew blown fuses with the
correct type. Fuses of different ratings are
physically interchangeable, but only fuses of
the proper rating should be used. Replacing a
fuse with one of a higher or lower value than
specified is not recommended. Each electrical
circuit needs a specific amount of protection.
The amperage value of each fuse is moulded
into the fuse body.
If the new fuse immediately fails, don’t
renew it again until the cause of the problem
is isolated and corrected. In most cases, the
cause will be a short-circuit in the wiring
caused by a broken or deteriorated wire.
4 Relays- general information
1
Several electrical accessories in the vehicle
use relays to transmit the electrical signal to
the component. If the relay is defective, thatcomponent will not operate properly. Relays
are electrically-operated switches, which are
often used in circuits drawing high levels of
current, or where more complex switching
arrangements are required.
The various relays are grouped together for
convenience in several locations under the
dash and in the engine compartment (see
accompanying illustration and illus-
tration 3.1).
If a faulty relay is suspected, it can be
removed and tested by a dealer or qualified
automotive electrician. No overhaul is
possible. Like fuses, defective relays must be
replaced with the correct type; some relays
look identical, but perform very different
functions.
5 Direction indicator/hazard
warning flasher unit- check
and renewal
2
Warning: Some later models are
equipped with an airbag or
Supplemental Restraint System
(SRS). To avoid possible damage
to this system, the manufacturer
recommends that, on airbag-equipped
models, the following procedure should be
left to a dealer service department, or
other specialist, because of the special
tools and techniques required. There is a
risk of injury if the airbag is accidentally
triggered.
1The direction indicator/hazard flasher unit is
a small canister- or box-shaped unit located
in the wiring harness on or near the steering
column. Access is gained by removing the
steering column shrouds (see illustration).
2When the flasher unit is functioning
properly, a regular clicking noise can be heard
from it when the indicators or hazard flashers
are switched on. If the direction indicators fail
on one side or the other, and the flasher unit
does not make its characteristic clicking
sound, a faulty direction indicator bulb is
indicated.
3If both direction indicators fail to blink, the
problem may be due to a blown fuse, a faulty
flasher unit, a broken switch or a loose or open
connection. If a quick check of the fusebox
12•2 Body electrical systems
4.2 Engine compartment relays3.1 The fusebox is located in the engine
compartment under a cover - the box also
includes several relays

8 Radio- removal and refitting
1
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you have
the correct activation code
before disconnecting the battery, Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Removal
1Disconnect the battery negative cable.
2The radios on most models are held in place
by internal clips which are usually located at
the sides or corners of the unit faceplate.
Removal requires a special tool which is
inserted into the holes to release the clips so
the radio can be pulled out. These tools can be
fabricated from heavy wire, or are available
from your dealer or a car audio specialist. On
anti-theft radios, the clips are moved in and
out by internal screws which require another
type of tool. Insert the tool into the holes until
the clips release, then withdraw the radio from
the dash panel. Disconnect the wiring from the
radio and remove it.3On some models, the radio is held in place
by screws located beneath the faceplate. The
control knobs must be pulled off before the
faceplate can be withdrawn.
Refitting
4Refitting is the reverse of removal.
9 Aerial- removal and refitting
1
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you have
the correct activation code
before disconnecting the battery, Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Removal
1Disconnect the battery negative cable.
2Use circlip pliers to unscrew the aerial
mounting nut.
3Open the boot lid/tailgate and remove the
left side trim panel. On some models, the jack
and tail light cluster cover will have to be
removed first.
4Unplug the aerial power and radio lead
connectors (as applicable), remove the
retaining bolts, and remove the aerial and
motor assembly.
Refitting
5Refitting is the reverse of removal.
10 Instrument cluster-
removal and refitting
2
Caution: The instrument cluster
and components are very
susceptible to damage from
static electricity. Make sure you
are earthed and have dischargedany static electricity (by touching an object
such as a metal water pipe) before
touching the cluster or components.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you have
the correct activation code
before disconnecting the battery, Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Removal
1Disconnect the battery negative cable.
2As necessary, remove the steering column
shrouds and lower trim panel (see Chap-
ter 11).
3Remove the screws holding the cluster to
the facia (see illustration). Note the location
of the lower screws to ensure they are refitted
in the same place. On 3-Series models, the
length of the two lower inner screws must not
exceed 9.5 mm.
4Tilt the top of the cluster back, reach
behind it and detach the electrical connectors
by pressing on the levers, then lift the cluster
out of the facia opening (see illustration).
5For access to the cluster components,
release the catches or remove the screws,
and separate the two halves (see
illustration).
Refitting
6Refitting is the reverse of removal.
11 Service Indicator (SI) board-
general information
All models that have service indicator lights
are equipped with a Service Indicator (SI)
board located in the instrument cluster. This
board turns the lights on at the proper mileage
intervals. The lights can only be turned off
using a special tool which plugs into the
engine check connector (see Chapter 1). The
12•4 Body electrical systems
10.5 Turn the plastic knobs to release the
back of the cluster (some models use
screws)10.4 Push on the levers to detach the
cluster electrical connectors10.3 Use a Phillips screwdriver to remove
the instrument cluster retaining screws
7.5 Insert a screwdriver into the openings
(arrowed) on each side of the switch to
release the clip while pulling out