1983 FIAT UNO automatic transmission

Safety First!0•5
Working on your car can be dangerous.
This page shows just some of the potential
risks and hazards, with the aim of creating a
safety-conscious attitude.
General hazards
Scalding
• Don’t remove the radiator or expansion
tank cap while the engine is hot.
• Engine oil, automatic transmission fluid or
power steering fluid may also be dangerously
hot if the engine has recently been running.
Burning
• Beware of burns from the exhaust system
and from any part of the engine. Brake discs
and drums can also be extremely hot
immediately after use.
Crushing
• When working under or near
a raised vehicle,
always
supplement the
jack with axle
stands, or use
drive-on
ramps.
Never
venture
under a car which
is only supported by a jack.
• Take care if loosening or tightening high-
torque nuts when the vehicle is on stands.
Initial loosening and final tightening should
be done with the wheels on the ground.
Fire
• Fuel is highly flammable; fuel vapour is
explosive.
• Don’t let fuel spill onto a hot engine.
• Do not smoke or allow naked lights
(including pilot lights) anywhere near a
vehicle being worked on. Also beware of
creating sparks
(electrically or by use of tools).
• Fuel vapour is heavier than air, so don’t
work on the fuel system with the vehicle over
an inspection pit.
• Another cause of fire is an electrical
overload or short-circuit. Take care when
repairing or modifying the vehicle wiring.
• Keep a fire extinguisher handy, of a type
suitable for use on fuel and electrical fires.
Electric shock
• Ignition HT
voltage can be
dangerous,
especially to
people with heart
problems or a
pacemaker. Don’t
work on or near the
ignition system with
the engine running or
the ignition switched on.• Mains voltage is also dangerous. Make
sure that any mains-operated equipment is
correctly earthed. Mains power points should
be protected by a residual current device
(RCD) circuit breaker.
Fume or gas intoxication
• Exhaust fumes are
poisonous; they often
contain carbon
monoxide, which is
rapidly fatal if inhaled.
Never run the
engine in a
confined space
such as a garage
with the doors shut.
• Fuel vapour is also
poisonous, as are the vapours from some
cleaning solvents and paint thinners.
Poisonous or irritant substances
• Avoid skin contact with battery acid and
with any fuel, fluid or lubricant, especially
antifreeze, brake hydraulic fluid and Diesel
fuel. Don’t syphon them by mouth. If such a
substance is swallowed or gets into the eyes,
seek medical advice.
• Prolonged contact with used engine oil can
cause skin cancer. Wear gloves or use a
barrier cream if necessary. Change out of oil-
soaked clothes and do not keep oily rags in
your pocket.
• Air conditioning refrigerant forms a
poisonous gas if exposed to a naked flame
(including a cigarette). It can also cause skin
burns on contact.
Asbestos
• Asbestos dust can cause cancer if inhaled
or swallowed. Asbestos may be found in
gaskets and in brake and clutch linings.
When dealing with such components it is
safest to assume that they contain asbestos.
Special hazards
Hydrofluoric acid
• This extremely corrosive acid is formed
when certain types of synthetic rubber, found
in some O-rings, oil seals, fuel hoses etc, are
exposed to temperatures above 400
0C. The
rubber changes into a charred or sticky
substance containing the acid. Once formed,
the acid remains dangerous for years. If it
gets onto the skin, it may be necessary to
amputate the limb concerned.
• When dealing with a vehicle which has
suffered a fire, or with components salvaged
from such a vehicle, wear protective gloves
and discard them after use.
The battery
• Batteries contain sulphuric acid, which
attacks clothing, eyes and skin. Take care
when topping-up or carrying the battery.
• The hydrogen gas given off by the battery
is highly explosive. Never cause a spark or
allow a naked light nearby. Be careful when
connecting and disconnecting battery
chargers or jump leads.
Air bags
• Air bags can cause injury if they go off
accidentally. Take care when removing the
steering wheel and/or facia. Special storage
instructions may apply.
Diesel injection equipment
• Diesel injection pumps supply fuel at very
high pressure. Take care when working on
the fuel injectors and fuel pipes.
Warning: Never expose the hands,
face or any other part of the body
to injector spray; the fuel can
penetrate the skin with potentially fatal
results.
Remember...
DO
• Do use eye protection when using power
tools, and when working under the vehicle.
• Do wear gloves or use barrier cream to
protect your hands when necessary.
• Do get someone to check periodically
that all is well when working alone on the
vehicle.
• Do keep loose clothing and long hair well
out of the way of moving mechanical parts.
• Do remove rings, wristwatch etc, before
working on the vehicle – especially the
electrical system.
• Do ensure that any lifting or jacking
equipment has a safe working load rating
adequate for the job.
A few tips
DON’T
• Don’t attempt to lift a heavy component
which may be beyond your capability – get
assistance.
• Don’t rush to finish a job, or take
unverified short cuts.
• Don’t use ill-fitting tools which may slip
and cause injury.
• Don’t leave tools or parts lying around
where someone can trip over them. Mop
up oil and fuel spills at once.
• Don’t allow children or pets to play in or
near a vehicle being worked on.

Roadside Repairs0•7
Connect one end of the red jump lead to
the positive (+) terminal of the flat
batteryConnect the other end of the red lead to
the positive (+) terminal of the booster
battery.Connect one end of the black jump lead
to the negative (-) terminal of the
booster battery
Connect the other end of the black
jump lead to a bolt or bracket on the
engine block, well away from the
battery, on the vehicle to be started.
–
+
+
–
123
4
Make sure that the jump leads will not
come into contact with the fan, drive-
belts or other moving parts of the
engine.5
Start the engine using the booster
battery, then with the engine running at
idle speed, disconnect the jump leads in
the reverse order of connection.6
Jump starting will get you out
of trouble, but you must correct
whatever made the battery go
flat in the first place. There are
three possibilities:
1The battery has been drained by
repeated attempts to start, or by
leaving the lights on.
2The charging system is not working
properly (alternator drivebelt slack
or broken, alternator wiring fault or
alternator itself faulty).
3The battery itself is at fault
(electrolyte low, or battery worn out).
Booster battery (jump) starting
When jump-starting a car using a
booster battery, observe the following
precautions:
4Before connecting the booster
battery, make sure that the ignition is
switched off.
4Ensure that all electrical equipment
(lights, heater, wipers, etc) is
switched off.4Make sure that the booster battery is
the same voltage as the discharged
one in the vehicle.
4If the battery is being jump-started
from the battery in another vehicle,
the two vehcles MUST NOT TOUCH
each other.
4Make sure that the transmission is in
neutral (or PARK, in the case of
automatic transmission).
Jump starting

Fault finding - all engines
Note: When investigating starting and uneven running faults, do not be tempted into snap diagnosis. Start from the beginning of the check
procedure and follow it through. It will take less time in the long run. Poor performance from an engine in terms of power and economy is not
normally diagnosed quickly. In any event, the ignition and fuel systems must be checked first before assuming any further investigation needs to
be made.
All engines 1•35
1
Engine fails to turn when starter operated
m mBattery discharged
m mBattery terminals loose or corroded
m mBattery earth to body defective
m mEngine/transmission earth strap broken or loose
m mDisconnected or broken wire in starter circuit
m mIgnition/starter switch defective
m mStarter motor or solenoid defective (see Chapter 9)
m mMajor mechanical failure (seizure) or long disuse (piston rings rusted
to bores)
Engine turns and fails to start
m mBattery discharged
m mBattery terminals loose or corroded
m mBattery or engine earth strap loose
m mStarter motor connections loose
m mOil in engine/transmission too thick
m mStarter motor defective
m mVapour lock in fuel line (in hot conditions or at high altitude)
m mBlocked float chamber needle valve
m mFuel pump filter blocked
m mChoked or blocked carburettor jets
m mFaulty fuel pump
m mFuel tank empty
m mOther fuel system fault (see Chapter 3)
m mShorted or disconnected low tension leads
m mDirty, incorrectly set, or pitted contact breaker points
m mContact breaker point spring earthed or broken
m mFaulty condenser
m mDefective ignition switch
m mFaulty coil
m mDamp or dirty HT leads, distributor cap or plug bodies
m mBroken, loose or disconnected LT leads
m mIgnition leads connected wrong way round
m mOther ignition fault (see Chapter 4)
m mValve timing incorrect (after rebuild)
Engine fires but will not run
m
mInsufficient choke (cold engine)
m mFuel starvation or tank empty
m mIgnition fault (see Chapter 4)
m mOther fuel system fault (see Chapter 3)
Engine stalls and will not restart
m
mToo much choke allowing too rich a mixture to wet plugs
m mFloat damaged or leaking or needle not seating
m mFloat lever incorrectly adjusted
m mIgnition failure - sudden
m mIgnition failure - misfiring precedes total stoppage
m mIgnition failure - in severe rain or after traversing water splash
m mNo petrol in petrol tank
m mPetrol tank breather choked
m mSudden obstruction in carburettor
m mWater in fuel system
Engine slow to warm up
m
mChoke linkage maladjusted
m mAir cleaner temperature control unit defective
m mThermostat stuck open (see Chapter 2)
m mOther fuel system fault (see Chapter 3)
Difficult starting when cold
m
mInsufficient choke
m mFouled or incorrectly gapped spark plugs
m mDamp or dirty HT leads, distributor cap or spark plug bodies
m mDirty or maladjusted contact breaker points
m mOther ignition fault or timing maladjustment (see Chapter 4)
m mFuel system or emission control fault (see Chapter 3)
m mPoor compression (may be due to incorrect valve clearances, burnt
or sticking valves, blown head gasket, worn or damaged pistons,
rings or bores)
m mIncorrect valve timing (after rebuild)
Difficult starting when hot
m
mIncorrect use of manual choke
m mFuel line vapour lock (especially in hot weather or at high altitudes)
m mIncorrect ignition timing
m mOther fuel system or emission control fault (see Chapter 3)
m mPoor compression (see above)
Engine lacks power
m
mIgnition timing incorrect
m mContact breaker points incorrectly gapped
m mIncorrectly set spark plugs
m mDirty contact breaker points
m mDistributor automatic advance and retard mechanisms not
functioning correctly
m mOther ignition system fault (see Chapter 4)
m mAir cleaner choked
m mCarburation too rich or too weak
m mFuel filter blocked
m mAir filter blocked
m mFaulty fuel pump giving top and fuel starvation
m mOther fuel system fault (see Chapter 3)
m mPoor compression
m mValve clearances incorrect
m mCarbon build-up in cylinder head
m mSticking or leaking valves
m mWeak or broken valve springs
m mWorn valve guides or stems
m mWorn pistons and piston rings
m mBurnt out valves
m mBlown cylinder head gasket (accompanied by increase in noise)
m mWorn pistons and piston rings
m mWorn or scored cylinder bore
m mBrakes binding
Engine misfires throughout speed range
m
mDefective or fouled spark plug
m mLoose, cracked or defective HT lead
m mMaladjusted, sticking or burnt valves
m mIgnition timing incorrect
m mBlown head gasket
m mFuel contaminated
m mOther ignition fault (see Chapter 4)
m mOther fuel system fault (see Chapter 3)
Poor engine braking
m
mHigh idle speed
m mOther fuel system fault (see Chapter 3)
m mLow compression

Ignition unit
36This comprises four elements (photo).
a) Power module - receives the ignition
advance command and controls the
conduction angle of the primary current
and energy stored in the coil.
b) Dissipater plate - eliminates the heat
which is generated by the high volume of
current.
c) Ignition coil with low primary resistance.
d) Distributor - a means of distributing high
tension to the spark plugs. The rotor is
driven in an anti-clockwise direction
(viewed from transmission) by a dog on
the end of the camshaft.
37The system incorporates a safety
pressure switch, which cuts out the ignition if
the turbocharging pressure exceeds a value
of between 0.84 and 0.93 bars (12.2 and
13.5 lbf/in
2) above atmospheric pressure.
Distributor (Microplex) -
removal and refitting#
38Remove the distributor cap and place it to
one side, complete with spark plug leads
(photo).
39Turn the crankshaft by means of the
pulley nut, or by raising and turning a front
wheel with top gear engaged, until No. 4
piston is on its firing stroke. This will be
indicated when the contact end of the rotorarm is aligned with the mark on the distributor
body rim, and the lug on the crankshaft pulley
is aligned with the timing pointer on the
engine. The right-hand underwing shield will
have to be removed in order to see the marks
(photo).
40Unscrew the distributor fixing nuts and
withdraw the distributor.
41When fitting the distributor, the offset
drive dog will automatically locate the
distributor rotor in its correct position, but the
distributor body may require rotating in order
to align the rim mark with the rotor. The
elongated slots for the fixing studs are to
permit initial alignment, not for subsequent
adjustment, as advance angle alterations are
carried out automatically by the system ECU
(photos).
42Tighten the nuts and refit the cap with
leads.
43Unless a stroboscope and a vacuum
pressure gauge are available, it will not be
possible to check the advance values with the
engine running. Where these instruments are
available, connect the vacuum gauge to the
inlet manifold, and the stroboscope in
accordance with the equipment manufac-
turer’s instructions. Refer to Fig. 13.79
according to the inlet manifold vacuum
pressure indicated.
Microplex ignition system
components - testing ª
44An ohmmeter and a voltmeter will be
required for these tests.
45Remove the multipin plug from the ECU.
Engine speed sensor
46Insert the probes of an ohmmeter
between terminals 3 and 16 of the multipin
connector; 618 to 748 ohms (1301 cc) or
578 to 782 ohms (1372 cc) should be
indicated.
47If necessary, carry out a check of the gap
between the sensor and flywheel teeth as
described in Chapter 4, Section 10.
Supplement: Revisions and information on later models 13•89
10.39 Crankshaft pulley timing marks
(arrowed)10.38 Removing the distributor cap10.36 Ignition coil (1) and power module (2)
on 1301 cc Turbo ie engine
Fig. 13.78 Rotor aligned with distributor
body rim mark - Microplex ignition system
(Sec 10)
10.41A Distributor body showing elongated
slots in the mounting lugs
Fig. 13.77 Crankshaft pulley timing mark
aligned with timing pointer - Microplex
ignition system (Sec 10)
1 TDC sensor10.41B Distributor drive dog
13

Glossary of Technical TermsREF•15
REF
GGapThe distance the spark must travel in
jumping from the centre electrode to the side
electrode 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.
JJump startStarting the engine of a vehicle
with a discharged or weak battery by
attaching jump leads from the weak battery to
a charged or helper battery.
LLoad Sensing Proportioning Valve (LSPV)A
brake hydraulic system control valve that
works like a proportioning valve, but also
takes into consideration the amount of weight
carried by the rear axle.
LocknutA nut used to lock an adjustment
nut, or other threaded component, in place.
For example, a locknut is employed to keep
the adjusting nut on the rocker arm in
position.
LockwasherA form of washer designed to
prevent an attaching nut from working loose.
MMacPherson strutA type of front
suspension system devised by Earle
MacPherson at Ford of England. In its original
form, a simple lateral link with the anti-roll bar
creates the lower control arm. A long strut - an
integral coil spring and shock absorber - is
mounted between the body and the steering
knuckle. Many modern so-called MacPherson
strut systems use a conventional lower A-arm
and don’t rely on the anti-roll bar for location.
MultimeterAn electrical test instrument with
the capability to measure voltage, current and
resistance.
NNOxOxides of Nitrogen. A common toxic
pollutant emitted by petrol and diesel engines
at higher temperatures.
OOhmThe unit of electrical resistance. One
volt applied to a resistance of one ohm will
produce a current of one amp.
OhmmeterAn instrument for measuring
electrical resistance.
O-ringA type of sealing ring made of a
special rubber-like material; in use, the O-ring
is compressed into a groove to provide the
sealing action.
Overhead cam (ohc) engineAn engine with
the camshaft(s) located on top of the cylinder
head(s).Overhead valve (ohv) engineAn engine with
the valves located in the cylinder head, but
with the camshaft located in the engine block.
Oxygen sensorA device installed in the
engine exhaust manifold, which senses the
oxygen content in the exhaust and converts
this information into an electric current. Also
called a Lambda sensor.
PPhillips screwA type of screw head having a
cross instead of a slot for a corresponding
type of screwdriver.
PlastigageA thin strip of plastic thread,
available in different sizes, used for measuring
clearances. For example, a strip of Plastigage
is laid across a bearing journal. The parts are
assembled and dismantled; the width of the
crushed strip indicates the clearance between
journal and bearing.
Propeller shaftThe long hollow tube with
universal joints at both ends that carries
power from the transmission to the differential
on front-engined rear wheel drive vehicles.
Proportioning valveA hydraulic control
valve which limits the amount of pressure to
the rear brakes during panic stops to prevent
wheel lock-up.
RRack-and-pinion steeringA steering system
with a pinion gear on the end of the steering
shaft that mates with a rack (think of a geared
wheel opened up and laid flat). When the
steering wheel is turned, the pinion turns,
moving the rack to the left or right. This
movement is transmitted through the track
rods to the steering arms at the wheels.
RadiatorA liquid-to-air heat transfer device
designed to reduce the temperature of the
coolant in an internal combustion engine
cooling system.
RefrigerantAny substance used as a heat
transfer agent in an air-conditioning system.
R-12 has been the principle refrigerant for
many years; recently, however, manufacturers
have begun using R-134a, a non-CFC
substance that is considered less harmful to
the ozone in the upper atmosphere.
Rocker armA lever arm that rocks on a shaft
or pivots on a stud. In an overhead valve
engine, the rocker arm converts the upward
movement of the pushrod into a downward
movement to open a valve.
Adjusting spark plug gap
Plastigage
Gasket

REF•16Glossary of Technical Terms
RotorIn a distributor, the rotating device
inside the cap that connects the centre
electrode and the outer terminals as it turns,
distributing the high voltage from the coil
secondary winding to the proper spark plug.
Also, that part of an alternator which rotates
inside the stator. Also, the rotating assembly
of a turbocharger, including the compressor
wheel, shaft and turbine wheel.
RunoutThe amount of wobble (in-and-out
movement) of a gear or wheel as it’s rotated.
The amount a shaft rotates “out-of-true.” The
out-of-round condition of a rotating part.
SSealantA liquid or paste used to prevent
leakage at a joint. Sometimes used in
conjunction with a gasket.
Sealed beam lampAn older headlight design
which integrates the reflector, lens and
filaments into a hermetically-sealed one-piece
unit. When a filament burns out or the lens
cracks, the entire unit is simply replaced.
Serpentine drivebeltA single, long, wide
accessory drivebelt that’s used on some
newer vehicles to drive all the accessories,
instead of a series of smaller, shorter belts.
Serpentine drivebelts are usually tensioned by
an automatic tensioner.
ShimThin spacer, commonly used to adjust
the clearance or relative positions between
two parts. For example, shims inserted into or
under bucket tappets control valve
clearances. Clearance is adjusted by
changing the thickness of the shim.
Slide hammerA special puller that screws
into or hooks onto a component such as a
shaft or bearing; a heavy sliding handle on the
shaft bottoms against the end of the shaft to
knock the component free.SprocketA tooth or projection on the
periphery of a wheel, shaped to engage with a
chain or drivebelt. Commonly used to refer to
the sprocket wheel itself.
Starter inhibitor switchOn vehicles with an
automatic transmission, a switch that
prevents starting if the vehicle is not in Neutral
or Park.
StrutSee MacPherson strut.
TTappetA cylindrical component which
transmits motion from the cam to the valve
stem, either directly or via a pushrod and
rocker arm. Also called a cam follower.
ThermostatA heat-controlled valve that
regulates the flow of coolant between the
cylinder block and the radiator, so maintaining
optimum engine operating temperature. A
thermostat is also used in some air cleaners in
which the temperature is regulated.
Thrust bearingThe bearing in the clutch
assembly that is moved in to the release
levers by clutch pedal action to disengage the
clutch. Also referred to as a release bearing.
Timing beltA toothed belt which drives the
camshaft. Serious engine damage may result
if it breaks in service.
Timing chainA chain which drives the
camshaft.
Toe-inThe amount the front wheels are
closer together at the front than at the rear. On
rear wheel drive vehicles, a slight amount of
toe-in is usually specified to keep the front
wheels running parallel on the road by
offsetting other forces that tend to spread the
wheels apart.
Toe-outThe amount the front wheels are
closer together at the rear than at the front. On
front wheel drive vehicles, a slight amount of
toe-out is usually specified.
ToolsFor full information on choosing and
using tools, refer to the Haynes Automotive
Tools Manual.
TracerA stripe of a second colour applied to
a wire insulator to distinguish that wire from
another one with the same colour insulator.
Tune-upA process of accurate and careful
adjustments and parts replacement to obtain
the best possible engine performance.TurbochargerA centrifugal device, driven by
exhaust gases, that pressurises the intake air.
Normally used to increase the power output
from a given engine displacement, but can
also be used primarily to reduce exhaust
emissions (as on VW’s “Umwelt” Diesel
engine).
UUniversal joint or U-jointA double-pivoted
connection for transmitting power from a
driving to a driven shaft through an angle. A
U-joint consists of two Y-shaped yokes and a
cross-shaped member called the spider.
VValveA device through which the flow of
liquid, gas, vacuum, or loose material in bulk
may be started, stopped, or regulated by a
movable part that opens, shuts, or partially
obstructs one or more ports or passageways.
A valve is also the movable part of such a
device.
Valve clearanceThe clearance between the
valve tip (the end of the valve stem) and the
rocker arm or tappet. The valve clearance is
measured when the valve is closed.
Vernier caliperA precision measuring
instrument that measures inside and outside
dimensions. Not quite as accurate as a
micrometer, but more convenient.
ViscosityThe thickness of a liquid or its
resistance to flow.
VoltA unit for expressing electrical
“pressure” in a circuit. One volt that will
produce a current of one ampere through a
resistance of one ohm.
WWeldingVarious processes used to join metal
items by heating the areas to be joined to a
molten state and fusing them together. For
more information refer to the Haynes
Automotive Welding Manual.
Wiring diagramA drawing portraying the
components and wires in a vehicle’s electrical
system, using standardised symbols. For
more information refer to the Haynes
Automotive Electrical and Electronic Systems
Manual.
Serpentine drivebelt