warning BMW 3 SERIES 1985 E30 Repair Manual

problem exists, a new subframe or steering
arm (5-Series) or steering knuckle (3-Series),
which is integral with the strut housing, should
be fitted as well as the new balljoint.
Renewal
Note: None of these balljoints can be serviced
or renewed individually. If one of them is worn,
a complete new arm must be fitted.
8 Front hub and wheel bearing
assembly-
removal and refitting
3
Note:Removing the front hub/bearing
assembly renders it unfit for re-use. A new
assembly will be required for refitting.
Removal
1Loosen the wheel bolts, then raise the front
of the vehicle, and support it securely on axle
stands. Remove the wheel bolts and the
wheel.
2Using a hammer and chisel, remove the
dust cap from the centre of the wheel hub
(see illustration).
3Unstake the hub nut (see illustration).
4Refit the wheel and lower the vehicle to the
ground. Loosen, but do not remove, the hub
nut.
Warning: Always loosen and
tighten the hub nut with the
vehicle on the ground. Theleverage needed to loosen the nut (which
is very tight) could topple the vehicle off a
lift or an axle stand.
5Raise the front of the vehicle, support it
securely on axle stands, and remove the front
wheel again.
6Remove the front brake caliper and
mounting bracket (see Chapter 9). There is no
need to disconnect the brake hose. Hang the
caliper out of the way with a piece of wire.
7Remove the brake disc (see Chapter 9).
8Remove the hub nut, and pull the hub and
bearing assembly off the stub axle. You may
have to tap it off if it’s stuck (see illustration).
If the inner race of the bearing remains on the
stub axle (it probably will), remove the dust
shield (rubber boot) behind the bearing, and
use a puller to remove the inner race (see
illustration).Refitting
9Fit a new dust shield.
10Push the new hub and bearing onto the
stub axle. If it’s necessary to use force, press
or drive only against the bearing inner race
(see illustration).
11Fit a new hub nut, and tighten it finger-
tight at this stage.
12Refit the brake disc, its countersunk
retaining screw, and the brake caliper (see
Chapter 9).
13Refit the wheel, and lower the vehicle to
the ground.
14Tighten the hub nut to the torque listed inthis Chapter’s Specifications. Again, make
sure you do this with the vehicle on the
ground, not up on axle stands.
15Raise the front of the vehicle and place it
securely on axle stands. Remove the wheel.
16Stake the collar of the nut into the groove
of the spindle.
17Apply suitable sealant to a new grease
cap, and fit the cap by driving it into place
with a soft-faced mallet.
18Refit the wheel and wheel bolts. Lower the
vehicle to the ground, and tighten the wheel
bolts to the torque listed in the Chapter 1
Specifications.
9 Rear shock absorbers
(3-Series)-
removal and refitting
3
Removal
Note:Although shock absorbers don’t always
wear out simultaneously, renew both left and
right shock absorbers at the same time, to
prevent handling peculiarities or abnormal ride
quality.
1Chock the front wheels.
2Raise the rear of the vehicle, and support it
securely on axle stands. Support the trailing
arm with a trolley jack. Place a block of wood
on the jack head to serve as a cushion.
3Remove the shock absorber lower
mounting bolt (see illustration).
10•8 Suspension and steering systems
9.3 Remove the shock absorber lower
mounting bolt (arrowed)8.10 Use a large socket or a suitable piece
of pipe to drive against the inner race of
the new bearing8.8b If the inner race of the bearing sticks
to the stub axle, use a puller to get it off
8.8a If the hub sticks, knock it loose with a
hammer8.3 Using a chisel, knock out the staked
portion of the hub nut8.2 Using a hammer and chisel, knock out
the dust cap in the centre of the hub

the longer side of the sleeve facing towards
the centre of the vehicle.
Refitting
12Refitting is the reverse of removal. Refit
the inner pivot bolt first. Don’t fully tighten the
nuts on the pivot bolts or the shock absorber
yet.
13Bleed the brakes as described in Chap-
ter 9.
14Support the trailing arm with a trolley jack,
and raise it to simulate normal ride height.
Tighten the bolts and nuts to the torques
listed in this Chapter’s Specifications.
15 Rear wheel bearings-
renewal
4
3-Series models
1Loosen the driveshaft nut and the rear
wheel bolts, then chock the front wheels.
Raise the rear of the vehicle and place it
securely on axle stands. Remove the rear
wheel. Note: Depending on the type of rear
wheel, it may be necessary to remove the
wheel first, remove the hubcap, then refit the
wheel and loosen the driveshaft nut.
2Remove the driveshaft (see Chapter 8).3On models with rear brake drums, remove
the drum. On models with rear disc brakes,
remove the brake caliper and mounting
bracket. Don’t disconnect the hose. Hang the
caliper out of the way with a piece of wire.
Remove the brake disc (see Chapter 9).
Working from behind, drive the wheel hub out
of the wheel bearing with a large socket or a
piece of pipe.
4Remove the large circlip (see illustration)
that holds the wheel bearing in the wheel
bearing housing, then drive out the bearing
with a large socket or piece of pipe.
5Refitting is basically the reverse of removal,
bearing in mind the following points:
a) Be extremely careful where you place the
socket or piece of pipe when you drive
the new bearing into the housing. It
should be butted up against the outer
race of the bearing. Driving in the new
bearing using the inner race will ruin the
bearing.
b) Refit the wheel and lower the vehicle to
the ground before attempting to tighten
the driveshaft nut to the torque listed in
the Chapter 8 Specifications.
5-Series models
6Chock the front wheels, then raise the rear
of the vehicle and support it securely on axle
stands. Disconnect the outer CV joint from the
drive flange (see Chapter 8). Support the outer
end of the driveshaft with a piece of wire -
don’t let it hang, as this could damage the
inner CV joint.
7Prise out the lockplate that secures the
drive flange nut (see illustration). Once
you’ve prised out an edge of the lockplate,
pull it out with a pair of needle-nose pliers.
8Lower the vehicle and unscrew the drive
flange nut, but don’t remove it yet. You’ll need
a long bar (see illustration).
Warning: Don’t attempt to loosen
this nut with the vehicle on axle
stands. The force required to
loosen the nut could topple the
vehicle from the stands.
9Loosen the rear wheel bolts, raise the rear
of the vehicle again, place it securely on axle
stands and remove the wheel.
10Remove the brake caliper and the brake
disc (see Chapter 9). Hang the caliper out of
the way with a piece of wire.
11Remove the drive flange nut. Using a
suitable puller, remove the drive flange (see
illustration).
12Using a soft-faced hammer, drive the stub
axle out of the bearing (see illustration). If the
bearing inner race comes off with the stub
Suspension and steering systems 10•11
15.7 Prise out the lockplate that secures
the drive flange nut - once you’ve prised
out an edge of the lockplate, pull it out
with a pair of needle-nose pliers15.4 An exploded view of the 3-Series rear
wheel bearing assembly14.8 On 1983 and later models, remove
one of these trailing arm-to-axle carrier
bolts (it doesn’t matter which one you
remove - one attaches the link to the
trailing arm, and the other attaches the link
to the axle carrier)
15.12 Using a soft-faced hammer, drive
the stub axle out of the bearing15.11 Remove the drive flange with a
puller15.8 Lower the vehicle and loosen the
drive flange nut
10
If the bearing inner race
sticks to the hub (it probably
will), use a puller to remove
the race from the hub.

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

indicates that the direction indicator and/or
hazard fuse has blown, check the wiring for a
short-circuit before fitting a new fuse.
4Make sure that the new unit is identical to
the original. Compare the old one to the new
one before fitting it.
5Refitting is the reverse of removal.
6 Steering column switches-
removal and refitting
1
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.
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.
1Disconnect the battery negative cable,
remove the steering wheel (see Chapter 10)
and steering column shrouds (see Chapter 11).
Direction indicator/headlight
switch
2Where necessary, remove the switch
mounting screws. Depress the tabs and pull
the switch out of the steering column
mounting (see illustration).
3Trace the switch wires down the steering
column to the electrical connector, and
unplug them (see illustration).
4Refitting is the reverse of removal.
Wiper/washer switch
5Where necessary, remove the switch
mounting screws.
6Depress the release clip, and detach the
switch from the steering column mounting
(see illustration). Trace the switch wiring
down the steering column to the electrical
connector, and unplug it.
7Refitting is the reverse of removal.
Cruise control switch
8Remove the wiper/washer switch.
9Where necessary, remove the switch
mounting screw. Squeeze the release tabs,
and withdraw the switch from the mounting
(see illustration).
10Disconnect the switch electrical
connector from the harness at the base of the
steering column.
11Refitting is the reverse of removal.
7 Ignition switch-
removal and refitting
1
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 specialtools and techniques required. 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, 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.
2Remove the steering wheel (see Chap-
ter 10).
3Remove the steering column shrouds (see
Chapter 11).
4Where necessary, remove the direction
indicator/headlight control switch (see Sec-
tion 6).
5Detach the clips by inserting a small
screwdriver into the openings on the sides
while pulling out on the switch (see
illustration).
6Unplug the electrical connector from the
harness at the base of the steering column,
and remove the switch.
Refitting
7Refitting is the reverse of removal.
Body electrical systems 12•3
6.3 Follow the wiring down the steering
column to the connector6.2 Squeeze the tabs to release the switch
from the mounting
6.9 Cruise control switch removal6.6 Squeeze the wiper/washer switch tabs
and pull it directly out of the mounting
12
5.1 The direction indicator/hazard warning
flasher unit is located on the steering
column on most models - squeeze the
tabs to detach it

SI board is a self-contained computer which
includes a chip and batteries.
The rechargeable SI board nickel cadmium
(nicad) batteries maintain power to the
computer memory in the event of a power
drop (such as during starting) or complete
power loss (such as a dead or disconnected
battery) (see illustration). This assures power
so the computer can continue to keep track of
mileage and turn the lights on at the proper
interval.
The batteries have a life of approximately
six years, at which time they must be replaced
with new ones. Also, since they are recharged
by the engine charging system, they can run
down prematurely if power is cut off for some
reason (such as a blown fuse, a fault in the
wiring, or extended storage of the vehicle).
Excessive heat or cold can also shorten
battery life, with heat the greatest enemy.
Extreme heat can cause the batteries to
actually split open, allowing acid to drip into
the instrument cluster.
Several instruments controlled by the SI
board can be affected by low or discharged
batteries. Symptoms of low or dead SI board
batteries can include inconsistent tachometer
and temperature gauge readings, background
radio noise, and the inability to turn the
service lights off with the special tool.
Although only complete SI boards are
available from the manufacturer, batteries are
available separately from aftermarket sources.
While it is possible for the home mechanic to
renew the batteries, they are soldered to the
board, so unless you are skilled at this and
have the proper tools, this job should be left
to an experienced electronics technician.
Considerable savings can be realised by
removing the instrument cluster (see
Section 10) and taking it to an electronics
specialist.
Caution: the instrument cluster
and components are very
susceptible to damage from
static electricity. Make sure you
are earthed and have discharged any
static electricity (by touching an object
such as a metal water pipe) before
touching the cluster components.12 Headlights- bulb renewal
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.
1Disconnect the battery negative cable.
Sealed-beam type
2Remove the grille (see Chapter 11).
3Remove the headlight retainer screws,
taking care not to disturb the adjustment
screws.
4Remove the retainer and pull the headlight
out enough to allow the connector to be
unplugged.
5Remove the headlight.
6To refit the headlight, plug the connector in,
place the headlight in position, and refit the
retainer and screws. Tighten the screws
securely.7Refit the grille. Connect the battery negative
cable.
Halogen bulb type
Warning: Halogen gas-filled bulbs
are under pressure, and may
shatter if the surface is scratched
or the bulb is dropped. Wear eye
protection, and handle the bulbs carefully,
grasping only the base whenever possible.
Do not touch the surface of the bulb with
your fingers, because the oil from your
skin could cause it to overheat and fail
prematurely.
8From behind the headlight assembly,
remove the outer cover (see illustration).
9Twist and release the inner cover from the
rear of the headlight (see illustration).
10Disconnect the wire from the rear of the
headlight bulb (see illustration).
11Release the clips, and withdraw the bulb
from the headlight unit (see illustration).
12Fit the new bulb using a reversal of the
removal procedure. Make sure that the clips
engage the bulb correctly.
13Connect the battery negative cable.
Body electrical systems 12•5
12.9 Twist and release the headlight inner
cover12.8 Removing the headlight rear outer
cover (3-Series shown)11.2 These batteries (arrowed) power the
Service Indicator (SI) board
12.11 Removing the headlight bulb (do not
touch the surface of the bulb with your
fingers)12.10 Disconnecting the wire from the rear
of the headlight bulb
12
If you do touch the headlamp
bulb surface, clean it with
methylated spirit.

12Refitting is a reversal of removal. When
fitting the motor, if necessary plug in the
connector and run the motor briefly until it is
in the “neutral” (wiper parked) position.
17 Heated rear window-
check and repair
2
1The heated rear window consists of a
number of horizontal elements on the glass
surface.
2Small breaks in the element can be repaired
without removing the rear window.
Check
3Switch on the ignition and the heated rear
window.
4Place the positive lead of a voltmeter to the
heater element nearest to the incoming power
source.
5Wrap a piece of aluminium foil around the
negative lead of the voltmeter on the positive
side of the suspected broken element, and
slide it slowly towards the negative side.
Watch the voltmeter needle - when it moves
from zero, you have located the break.
Repair
6Repair the break in the line using a repair kit
recommended specifically for this purpose,
such as BMW repair kit No. 81 22 9 (or
equivalent). Included in this kit is plastic
conductive epoxy. The following paragraphs
give general instructions for this type of repair;
follow the instructions supplied with the repair
kit if they are different.
7Prior to repairing a break, switch off the
circuit and allow it to cool down for a few
minutes.
8Lightly buff the element area with fine steel
wool, then clean it thoroughly.
9Use masking tape to mask off the area of
repair, leaving a slit to which the epoxy can be
applied.
10Mix the epoxy thoroughly, according to
the instructions on the package.
11Apply the epoxy material to the slit in the
masking tape, overlapping the undamaged
area about 20 mm on each end.12Allow the repair to cure for 24 hours
before removing the tape and using the
heated rear window.
18 Supplemental Restraint
System (SRS)- general
information
Later models are equipped with a
Supplemental Restraint System (SRS),
incorporating an airbag. This system is
designed to protect the driver from serious
injury in the event of a head-on or frontal
collision. It consists of an airbag module in the
centre of the steering wheel, two crash
sensors mounted on the front inner wing
panels, and a crash safety switch located
inside the passenger compartment.
The airbag module contains a housing
incorporating the airbag and the inflator units.
The inflator assembly is mounted on the back
of the housing over a hole through which gas
is expelled, inflating the bag almost instanta-
neously when an electrical signal is sent from
the system. This signal is carried by a wire
which is specially wound with several turns,
so the signal will be transmitted regardless of
the steering wheel position.
The SRS system has three sensors: two at
the front, mounted on the inner wing panels
(see illustration), and a safety switch located
inside the passenger compartment. The crash
sensors are basically pressure-sensitive
switches, which complete an electrical circuit
during an impact of sufficient force. The
electrical signal from the crash sensors is sent
to a third sensor, which then completes the
circuit and inflates the airbag.
The module containing the safety switch
monitors the system operation. It checks the
system every time the vehicle is started,
causing the AIRBAG warning light to come on,
then go out if the system is operating
correctly. If there is a fault in the system, the
light will stay on. If the AIRBAG warning light
does stay on, or if it comes on while driving,
take the vehicle to your dealer immediately.
19 Cruise control system-
description and check
1
The cruise control system maintains vehicle
speed using a vacuum-actuated servo motor
located in the engine compartment, which is
connected to the throttle linkage by a cable.
The system consists of the servo motor,
clutch switch, brake switch, control switches,
a relay, and associated vacuum hoses.
Because of the complexity of the cruise
control system, repair should be left to a
dealer service department. However, it is
possible for the home mechanic to make
simple checks of the wiring and vacuum
connections for minor faults which can be
easily repaired. These include:
a) Inspect the cruise control actuating switches
for broken wires and loose connections.
b) Check the cruise control fuse.
c) The cruise control system is operated by
vacuum, so it’s critical that all vacuum
switches, hoses and connections are
secure. Check the hoses in the engine
compartment for loose connections,
cracks, or obvious vacuum leaks.
20 Central locking system-
description and check
2
The central door locking system operates
the door lock actuators mounted in each
door. The system consists of the switches,
actuators and associated wiring. Diagnosis is
limited to simple checks of the wiring
connections and actuators for minor faults
which can be easily repaired. These include:
a) Check the system fuse and/or circuit
breaker (where applicable).
b) Check the switch wires for damage and
loose connections. Check the switches
for continuity.
c) Remove the door trim panel(s), and check
the actuator wiring connections to see if
they’re loose or damaged. Inspect the
actuator rods to make sure they aren’t
12•8 Body electrical systems
18.3 The SRS system crash sensors
(arrowed) are located in the engine
compartment - check the wiring regularly
for damage16.11b Tailgate wiper motor (5-Series)16.11c Wiper blade and pivot mechanism
on the rear window (5-Series)

REF•2MOT Test Checks
Seat belts and seats
Note: The following checks are applicable to
all seat belts, front and rear.
MExamine the webbing of all the belts
(including rear belts if fitted) for cuts, serious
fraying or deterioration. Fasten and unfasten
each belt to check the buckles. If applicable,
check the retracting mechanism. Check the
security of all seat belt mountings accessible
from inside the vehicle.
MThe front seats themselves must be
securely attached and the backrests must
lock in the upright position.
Doors
MBoth front doors must be able to be opened
and closed from outside and inside, and must
latch securely when closed.
Vehicle identification
MNumber plates must be in good condition,
secure and legible, with letters and numbers
correctly spaced – spacing at (A) should be
twice that at (B).
MThe VIN plate and/or homologation plate
must be legible.
Electrical equipment
MSwitch on the ignition and check the
operation of the horn.
MCheck the windscreen washers and wipers,
examining the wiper blades; renew damaged
or perished blades. Also check the operation
of the stop-lights.
MCheck the operation of the sidelights and
number plate lights. The lenses and reflectors
must be secure, clean and undamaged.
MCheck the operation and alignment of the
headlights. The headlight reflectors must not
be tarnished and the lenses must be
undamaged.
MSwitch on the ignition and check the
operation of the direction indicators (including
the instrument panel tell-tale) and the hazard
warning lights. Operation of the sidelights and
stop-lights must not affect the indicators - if it
does, the cause is usually a bad earth at the
rear light cluster.
MCheck the operation of the rear foglight(s),
including the warning light on the instrument
panel or in the switch.
Footbrake
MExamine the master cylinder, brake pipes
and servo unit for leaks, loose mountings,
corrosion or other damage.
MThe fluid reservoir must be secure and the
fluid level must be between the upper (A) and
lower (B) markings.MInspect both front brake flexible hoses for
cracks or deterioration of the rubber. Turn the
steering from lock to lock, and ensure that the
hoses do not contact the wheel, tyre, or any
part of the steering or suspension mechanism.
With the brake pedal firmly depressed, check
the hoses for bulges or leaks under pressure.
Steering and suspension
MHave your assistant turn the steering wheel
from side to side slightly, up to the point where
the steering gear just begins to transmit this
movement to the roadwheels. Check for
excessive free play between the steering
wheel and the steering gear, indicating wear or
insecurity of the steering column joints, the
column-to-steering gear coupling, or the
steering gear itself.
MHave your assistant turn the steering wheel
more vigorously in each direction, so that the
roadwheels just begin to turn. As this is done,
examine all the steering joints, linkages,
fittings and attachments. Renew any
component that shows signs of wear or
damage. On vehicles with power steering,
check the security and condition of the
steering pump, drivebelt and hoses.
MCheck that the vehicle is standing level,
and at approximately the correct ride height.
Shock absorbers
MDepress each corner of the vehicle in turn,
then release it. The vehicle should rise and
then settle in its normal position. If the vehicle
continues to rise and fall, the shock absorber
is defective. A shock absorber which has
seized will also cause the vehicle to fail.
2Checks carried out
WITH THE VEHICLE ON THE
GROUND

REF•9
REF
Fault Finding
Engine
m mEngine will not rotate when attempting to start
m mEngine rotates, but will not start
m mEngine hard to start when cold
m mEngine hard to start when hot
m mStarter motor noisy or excessively-rough in engagement
m mEngine starts, but stops immediately
m mOil puddle under engine
m mEngine idles erratically
m mEngine misses at idle speed
m mEngine misses throughout driving speed range
m mEngine misfires on acceleration
m mEngine surges while holding accelerator steady
m mEngine stalls
m mEngine lacks power
m mEngine backfires
m mPinking or knocking engine sounds when accelerating
or driving uphill
m mEngine runs with oil pressure light on
m mEngine runs-on after switching off
Engine electrical system
m
mBattery will not hold charge
m mIgnition (no-charge) warning light fails to go out
m mIgnition (no-charge) warning light fails to come on
when key is turned
Fuel system
m mExcessive fuel consumption
m mFuel leakage and/or fuel odour
Cooling system
m
mOverheating
m mOvercooling
m mExternal coolant leakage
m mInternal coolant leakage
m mCoolant loss
m mPoor coolant circulation
Clutch
m
mPedal travels to floor - no pressure or very little resistance
m mFluid in area of master cylinder dust cover and on pedal
m mFluid on slave cylinder
m mPedal feels “spongy” when depressed
m mUnable to select gears
m mClutch slips (engine speed increases with no increase in
vehicle speed)
m mGrabbing (chattering) as clutch is engaged
m mNoise in clutch area
m mClutch pedal stays on floor
m mHigh pedal effort
Manual transmission
m
mVibration
m mNoisy in neutral with engine running
m mNoisy in one particular gear
m mNoisy in all gears
m mSlips out of gear
m mLeaks lubricant
Automatic transmission
m
mFluid leakage
m mTransmission fluid brown, or has a burned smell
m mGeneral shift mechanism problems
m mTransmission will not kickdown with accelerator pedal
pressed to the floor
m mEngine will start in gears other than Park or Neutral
m mTransmission slips, shifts roughly, is noisy, or has no drive
in forward or reverse gears
Brakes
m mVehicle pulls to one side during braking
m mNoise (high-pitched squeal) when the brakes are applied
m mBrake vibration (pedal pulsates)
m mExcessive pedal effort required to stop vehicle
m mExcessive brake pedal travel
m mDragging brakes
m mGrabbing or uneven braking action
m mBrake pedal feels “spongy” when depressed
m mBrake pedal travels to the floor with little resistance
m mHandbrake does not hold
Suspension and steering
m
mVehicle pulls to one side
m mAbnormal or excessive tyre wear
m mWheel makes a “thumping” noise
m mShimmy, shake or vibration
m mHigh steering effort
m mPoor steering self-centring
m mAbnormal noise at the front end
m mWandering or poor steering stability
m mErratic steering when braking
m mExcessive pitching and/or rolling around corners or
during braking
m mSuspension bottoms
m mUnevenly-worn tyres
m mExcessive tyre wear on outside edge
m mExcessive tyre wear on inside edge
m mTyre tread worn in one place
m mExcessive play or looseness in steering system
m mRattling or clicking noise in steering gear