1991 BMW 5 SERIES Check control

12•12 Wiring diagrams
Typical check control, electric mirrors, stop and parking light (3 of 4)

REF•15
REF
Fault Finding
Suspension and steering
Note:Before assuming that a problem exists, check the following
items:
a) Tyre pressures and tyre condition (also check for out-of-round or
out-of-balance tyres, and bent wheel rims).
b) Steering universal joints from the column to the steering gear (for
play or wear).
c) Front and rear suspension, and the rack-and-pinion assembly (for
loose or damaged parts).
d) Wheel bearings (wheel wobble or roughness when spun).
Vehicle pulls to one side
m mMismatched or uneven tyres (Chapter 10).
m mBroken or sagging springs (Chapter 10).
m mFront wheel or rear wheel alignment incorrect (Chapter 10).
m mFront brake problem (Chapter 9).
Abnormal or excessive tyre wear
m
mFront wheel or rear wheel alignment incorrect (Chapter 10).
m mSagging or broken springs (Chapter 10).
m mTyre out of balance (Chapter 10).
m mWorn shock absorber (Chapter 10).
m mOverloaded vehicle or unsympathetic driving style.
m mTyres not rotated regularly.
Wheel makes a “thumping” noise
m
mBlister or bump on tyre (Chapter 10).
m mFaulty shock absorber action (Chapter 10).
m mWheel bolts loose.
Shimmy, shake or vibration
m
mTyre or wheel out of balance or out of round (Chapter 10).
m mLoose, worn or incorrectly-adjusted wheel bearings (Chapter 1).
m mWorn tie-rod ends (Chapter 10).
m mWorn balljoints (Chapter 10).
m mExcessive wheel run-out (Chapter 10).
m mBlister or bump on tyre (Chapter 10).
m mWheel bolts loose.
High steering effort
m
mLack of lubrication at balljoints, tie-rod ends and steering gear
(Chapter 1).
m mIncorrect front wheel alignment (Chapter 10).
m mLow tyre pressure(s) (Chapter 1).
m mPower steering fluid low, or steering pump drivebelt slipping,
where applicable (Chapter 10)
Poor steering self-centring
m mLack of lubrication at balljoints and tie-rod ends (Chapter 1).
m mBinding in balljoints (Chapter 10).
m mBinding in steering column (Chapter 10).
m mLack of lubricant in steering gear (Chapter 10).
m mInaccurate front wheel alignment (Chapter 10).
Abnormal noise at the front end
m
mLack of lubrication at balljoints and tie-rod ends (Chapter 1).
m mDamaged shock absorber mounting (Chapter 10).
m mWorn control arm bushings or tie-rod ends (Chapter 10).
m mLoose anti-roll bar (Chapter 10).
m mLoose wheel bolts.
m mLoose suspension mounting bolts (Chapter 10).
Wandering or poor steering stability
m
mMismatched or uneven tyres (Chapter 10).
m mLack of lubrication at balljoints and tie-rod ends (Chapter 1).
m mWorn shock absorbers (Chapter 10).
m mLoose anti-roll bar (Chapter 10).
m mBroken or sagging springs (Chapter 10).
m mFront or rear wheel alignment incorrect (Chapter 10).
Erratic steering when braking
m
mWheel bearings worn (Chapter 1).
m mBroken or sagging springs (Chapter 10).
m mLeaking wheel cylinder (rear drum brake models) or caliper
(Chapter 9).
m mWarped discs (Chapter 9).
Excessive pitching and/or rolling around corners or
during braking
m mLoose anti-roll bar (Chapter 10).
m mWorn shock absorbers or mountings (Chapter 10).
m mBroken or sagging springs (Chapter 10).
m mOverloaded vehicle.
Suspension bottoms
m
mOverloaded vehicle.
m mWorn shock absorbers (Chapter 10).
m mBroken or sagging springs, or incorrect springs fitted (Chapter 10).
Unevenly-worn tyres
m
mFront wheel or rear wheel alignment incorrect (Chapter 10).
m mWorn shock absorbers (Chapter 10).
m mWheel bearings worn (Chapter 10).
m mExcessive tyre or wheel run-out (Chapter 10).
m mWorn balljoints (Chapter 10).
Excessive tyre wear on outside edge
m
mTyre pressures incorrect (Chapter 1).
m mExcessive cornering speed.
m mWheel alignment incorrect (excessive toe-in) (Chapter 10).
m mSuspension components damaged (Chapter 10).
Excessive tyre wear on inside edge
m
mTyre pressures incorrect (Chapter 1).
m mWheel alignment incorrect (excessive toe-out) (Chapter 10).
m mLoose or damaged steering components (Chapter 10).
Tyre tread worn in one place
m
mTyres out of balance.
m mDamaged or buckled wheel. Inspect and renew if necessary.
m mDefective tyre (Chapter 1).
Excessive play or looseness in steering system
m
mWheel bearing(s) worn (Chapter 10.
m mTie-rod end loose or worn (Chapter 10).
m mSteering gear mountings loose (Chapter 10).
Rattling or clicking noise in steering gear
m
mInsufficient or incorrect lubricant in rack-and-pinion assembly
(Chapter 10).
m mSteering gear mountings loose (Chapter 10).

REF•22Glossary of Technical Terms
EEGR valveA valve used to introduce exhaust
gases into the intake air stream.
Electronic control unit (ECU)A computer
which controls (for instance) ignition and fuel
injection systems, or an anti-lock braking
system. For more information refer to the
Haynes Automotive Electrical and Electronic
Systems Manual.
Electronic Fuel Injection (EFI)A computer
controlled fuel system that distributes fuel
through an injector located in each intake port
of the engine.
Emergency brakeA braking system,
independent of the main hydraulic system,
that can be used to slow or stop the vehicle if
the primary brakes fail, or to hold the vehicle
stationary even though the brake pedal isn’t
depressed. It usually consists of a hand lever
that actuates either front or rear brakes
mechanically through a series of cables and
linkages. Also known as a handbrake or
parking brake.
EndfloatThe amount of lengthwise
movement between two parts. As applied to a
crankshaft, the distance that the crankshaft
can move forward and back in the cylinder
block.
Engine management system (EMS)A
computer controlled system which manages
the fuel injection and the ignition systems in
an integrated fashion.
Exhaust manifoldA part with several
passages through which exhaust gases leave
the engine combustion chambers and enter
the exhaust pipe.
FFan clutchA viscous (fluid) drive coupling
device which permits variable engine fan
speeds in relation to engine speeds.Feeler bladeA thin strip or blade of hardened
steel, ground to an exact thickness, used to
check or measure clearances between parts.
Firing orderThe order in which the engine
cylinders fire, or deliver their power strokes,
beginning with the number one cylinder.
Flywheel A heavy spinning wheel in which
energy is absorbed and stored by means of
momentum. On cars, the flywheel is attached
to the crankshaft to smooth out firing
impulses.
Free playThe amount of travel before any
action takes place. The “looseness” in a
linkage, or an assembly of parts, between the
initial application of force and actual
movement. For example, the distance the
brake pedal moves before the pistons in the
master cylinder are actuated.
FuseAn electrical device which protects a
circuit against accidental overload. The typical
fuse contains a soft piece of metal which is
calibrated to melt at a predetermined current
flow (expressed as amps) and break the
circuit.
Fusible linkA circuit protection device
consisting of a conductor surrounded by
heat-resistant insulation. The conductor is
smaller than the wire it protects, so it acts as
the weakest link in the circuit. Unlike a blown
fuse, a failed fusible link must frequently be
cut from the wire for replacement.
GGapThe distance the spark must travel in
jumping from the centre electrode to the sideelectrode in a spark plug. Also refers to the
spacing between the points in a contact
breaker assembly in a conventional points-
type ignition, or to the distance between the
reluctor or rotor and the pickup coil in an
electronic ignition.
GasketAny thin, soft material - usually cork,
cardboard, asbestos or soft metal - installed
between two metal surfaces to ensure a good
seal. For instance, the cylinder head gasket
seals the joint between the block and the
cylinder head.
GaugeAn instrument panel display used to
monitor engine conditions. A gauge with a
movable pointer on a dial or a fixed scale is an
analogue gauge. A gauge with a numerical
readout is called a digital gauge.
HHalfshaftA rotating shaft that transmits
power from the final drive unit to a drive
wheel, usually when referring to a live rear
axle.
Harmonic balancerA device designed to
reduce torsion or twisting vibration in the
crankshaft. May be incorporated in the
crankshaft pulley. Also known as a vibration
damper.
HoneAn abrasive tool for correcting small
irregularities or differences in diameter in an
engine cylinder, brake cylinder, etc.
Hydraulic tappetA tappet that utilises
hydraulic pressure from the engine’s
lubrication system to maintain zero clearance
(constant contact with both camshaft and
valve stem). Automatically adjusts to variation
in valve stem length. Hydraulic tappets also
reduce valve noise.
IIgnition timingThe moment at which the
spark plug fires, usually expressed in the
number of crankshaft degrees before the
piston reaches the top of its stroke.
Inlet manifoldA tube or housing with
passages through which flows the air-fuel
mixture (carburettor vehicles and vehicles with
throttle body injection) or air only (port fuel-
injected vehicles) to the port openings in the
cylinder head.
Exhaust manifold
Feeler blade
Adjusting spark plug gap
Gasket
EGR valve

REF•25
REF
Index
Note: References throughout this index relate to Chapter•page number
A
ABS - 9•2
Accelerator cable - 4•9
Acknowledgements - 0•4
Aerial - 12•4
Air bags - 0•5
Air cleaner - 4•8
Air conditioning system - 3•2, 3•7, 3•8,
3•9, 3•10
Air filter - 1•20
Air gap - 5•7
Air intake system - 4•2, 4•14
Airflow meter - 4•15, 6•4
Alternator - 5•10
Anti-lock Braking system (ABS) - 9•2
Anti-roll bar - 10•4, 10•9
Anti-theft audio system - 0•7
Antifreeze - 1•3, 1-8, 3•2
Asbestos - 0•5
ATF - 1•3, 1•13, 1•23
Automatic choke - 4•13
Automatic transmission- 7B•1et seq
Automatic transmission fault finding -
7B•4, REF•13
Automatic transmission fluid - 1•3, 1•13,
1•23
B
Backfire - REF•11
Balljoints - 10•7
Battery - 0•5, 1•16, 5•2
Battery fault - REF•11
Big-end bearings - 2B•17, 2B•21
Bleeding brakes - 9•14
Bleeding clutch - 8•4
Bleeding power steering - 10•16Block - 2B•14, 2B•15
Blower motor - 3•7
Body corrosion - REF•4
Body electrical systems- 12•1et seq
Bodywork and fittings- 11•1et seq
Bonnet - 11•4
Boot lid - 11•6
Boots - 8•9, 10•13
Brake fluid - 1•3, 1•9
Brake lines and hoses - 1•22, 9•13
Braking system- 1•22, 9•1et seq,REF•1,
REF•2, REF•3
Braking system fault finding - REF•14
Bulbs - 12•6
Bumpers - 11•6
Burning - 0•5
C
Cables - 4•9, 5•2, 7B•3, 9•12
Calipers - 9•4
Cam followers - 2B•11
Camshaft - 2A•12, 2B•11
Carburettor - 4•10, 4•11
Carpets - 11•2
Catalytic converter - 4•20, 6•6
Central locking - 12•8
Charging - 1•17, 5•9
Chemicals - REF•18
Choke - 4•13
Clutch and driveline- 8•1et seq
Clutch fault finding - REF•12
Clutch fluid - 1•3, 1•9
CO level adjustment - 1•15, REF•4
Coil - 5•5
Coil springs - 10•7, 10•9
Cold start injectors - 4•17, 4•18
Compression check - 2B•4Compressor - 3•8
Condenser - 3•9
Connecting rods -2B•12, 2B•16, 2B•21
Constant velocity (CV) joint - 8•2, 8•8, 8•9
Continuity check - 12•2
Control arm - 10•4, 10•5
Conversion factors - REF•17
Coolant - 1•3, 1•8
Coolant pump - 3•5
Coolant temperature sender unit - 3•6
Coolant temperature sensor - 6•2
Cooling fan - 3•4
Cooling, heating and air conditioning
systems- 1•21, 1•24, 3•1et seq
Cooling system fault finding - REF•12
Crankshaft - 2A•12, 2A•13, 2A•19, 2B•13,
2B•17, 2B•19, 2B•20
Cruise control - 12•3, 12•8
Crushing - 0•5
Cushion - 11•9
CV joints - 8•2, 8•8, 8•9
Cylinder head - 2A•13, 2B•7, 2B•10, 2B•12
Cylinder honing - 2B•15
D
Dents in bodywork - 11•2
Differential (final drive) - 8•2, 8•10, 8•11
Differential oil -1•3, 1•19, 1•26
Direction indicators - 12•2, 12•3
Discs - 1•22, 9•5
Distributor - 1•18, 5•4
Door - 11•6, 11•8, REF•2
Drivebelts - 1•14
Driveplate - 2A•18
Driveshafts - 1•22, 8•2, 8•9
Drums - 1•23

REF•26Index
E
Earth check - 12•2
Electric fan - 3•4
Electric shock - 0•5
Electric windows - 12•9
Electrical equipment - REF•2
Electrical system fault finding - 12•1
Electronic control system - 4•3, 4•14
Electronic control unit (ECU) - 6•1
Engine fault finding - REF•10
Engine tune-up - 1•7
Engine electrical systems- 5•1et seq
Engine electrical systems fault finding -
REF•11
Engine management and emission control
systems- 6•1et seq
Engine oil - 1•3, 1•7, 1•11
Environmental considerations - REF•8
Evaporative emissions control (EVAP)
system - 1•26, 6•5
Evaporator - 3•10
Exhaust emission checks - REF•4
Exhaust manifold - 2A•6
Exhaust system - 1•21, 4•20, REF•3
F
Fan - 3•4, 3•5
Fault finding- REF•9et seq
Fault finding - automatic transmission -
7B•2, REF•13
Fault finding - braking system - REF•14
Fault finding - clutch - REF•12
Fault finding - cooling system - REF•12
Fault finding - electrical system - 12•1,
REF•11
Fault finding - engine - REF•10
Fault finding - fuel system - 4•21, REF•12
Fault finding - manual transmission -
REF•13
Fault finding - suspension and steering -
REF•15
Filling - 11•3
Final drive - 8•2, 8•10, 8•11
Final drive oil - 1•3, 1•19, 1•26
Fire - 0•5
Flexible coupling - 8•7
Fluid level checks - 1•7
Fluid seals - 7B•5
Flywheel - 2A•18
Fuel and exhaust systems- 1•20, 4•1et
seq,REF•4
Fuel system fault finding - REF•12
Fuel filter - 1•25
Fuel hoses - 1•14
Fuel injection system - 4•3, 4•14
Fuel injection system - fault finding - 4•21
Fuel injectors - 4•18
Fuel level sender unit - 4•5, 4•6
Fuel lines and fittings - 4•7
Fuel pressure - 4•3
Fuel pressure regulator - 4•16
Fuel pump - 4•3, 4•4, 4•5
Fuel tank - 4•7, 4•8
Fume or gas intoxication - 0•5
Fuses - 12•2
G
Gaiters - 1•22, 8•9, 10•13
Gashes in bodywork - 11•2
Gaskets - REF•8
Gear lever - 7A•1
Gearbox - SeeManual transmission
Gearbox oil - 1•3, 1•19, 1•25
General engine overhaul procedures-
2B•1et seq
Glass - 11•4, 11•8
Glossary of technical terms - REF•20
Grille - 11•4
H
Handbrake - 1•23, 9•2, 9•12, REF•1
Handbrake fault - REF•14
Handles - 11•8
Hazard warning flasher - 12•2
HC emissions - REF•4
Headlights - 12•3, 12•5, 12•6
Heated rear window - 12•8
Heater - 3•2, 3•7, 3•8
Hinges - 11•4
HT leads - 1•18
Hubs - 10•8, 10•11, REF•3
Hydraulic servo - 9•11
Hydraulic tappets - 2B•11
Hydrofluoric acid - 0•5
I
Idle air stabiliser valve - 4•18
Idle speed adjustment - 1•15
Ignition coil - 5•5
Ignition control unit - 5•6, 5•7
Ignition sensors - 5•8
Ignition switch - 12•3
Ignition system - 5•3
Ignition timing - 5•4
Ignition timing sensors - 6•4
Impulse generator - 5•6, 5•7
In-car engine repair procedures- 2A•1et
seq
Indicators - 12•2, 12•3
Information sensors - 6•2
Injectors - 4•18
Input shaft - 7A•2
Instrument cluster - 12•4
Instrument panel language display - 0•7
Intake manifold - 2A•4
Intermediate shaft - 2A•12, 2B•14, 2B•19
Introduction to the BMW 3- and 5-Series -
0•4
J
Jacking - 0•8
Joint mating faces - REF•8
Jump starting - 0•9
K
Kickdown cable - 7B•3
L
L-Jetronic fuel injection system - 4•14,
4•19
Language display - 0•7
Latch - 11•8
Leaks - 0•10, 7B•3, REF•12, REF•13
Locknuts, locktabs and washers - REF•8
Locks - 11•4, 11•8
Lubricants - REF•18
M
Main bearings - 2B•17, 2B•19
Manifolds - 2A•4, 2A•6
Manual transmission- 7A•1et seq
Manual transmission fault finding - REF•13
Manual transmission oil - 1•3, 1•19, 1•25
Master cylinder - 8•3, 9•9
Mechanical fan - 3•4, 3•5
Mirrors - 11•8, REF•1
Misfire - REF•11
Mixture - REF•4
MOT test checks- REF•1 et seq
Motronic engine management system -
6•1
Motronic fuel injection system - 4•14, 4•19
Mountings - 2A•19, 7A•3
O
Oil - differential - 1•19, 1•26
Oil - engine - 1•3, 1•7, 1•11
Oil - final drive - 1•3
Oil - manual transmission - 1•3, 1•19, 1•25
Oil filter - 1•11, 1•12
Oil pump - 2A•16
Oil seals - 2A•12, 2A•13, 2A•19, 2B•20,
7A•2, 7B•5, 8•10, 8•12, REF•8
Open-circuit - 12•2
Output shaft - 7A•2, 7B•5
Overcooling - REF•12
Overheating - REF•12
Oxygen sensor - 6•2
P
Pads - 9•2, 9•3
Pedals - 8•3, 9•13
Pinion oil - 8•12
Pinking - REF•11
Piston rings - 2B•18
Pistons - 2B•12, 2B•16, 2B•21
Plastic components - 11•3
Poisonous or irritant substances - 0•5
Position sensors - 5•8
Positive crankcase ventilation (PCV)
system - 6•4
Power steering - 1•14, 10•15, 10•16
Power steering fluid - 1•12
Propeller shaft - 8•2, 8•6, 8•8
Pulse sensor - 5•8
Purge valve - 6•5