1983 FIAT UNO wiring

REPAIRS & OVERHAUL
Engine and Associated Systems
Engine (also see Chapter 13)Page 1•1
Cooling and heating systems (also see Chapter 13)Page2•1
Fuel system (also see Chapter 13)Page 3•1
Ignition system (also see Chapter 13)Page4•1
Transmission
Clutch (also see Chapter 13)Page5•1
Transmission (also see Chapter 13)Page6•1
Driveshafts, hubs, roadwheels and tyres (also see Chapter 13)Page7•1
Brakes
Braking system(also see Chapter 13)Page 8•1
Electrical
Electrical system(also see Chapter 13)Page 9•1
Steering and suspension
SteeringPage 10•1
Suspension (also see Chapter 13)Page 11•1
Bodywork
Bodywork (also see Chapter 13)Page 12•1
Additional information
Supplement: Revisions and information on later models Page 13•1
Wiring DiagramsPage 14•1
REFERENCE
MOT Test Checks PageREF•1
Tools and Working Facilities Page REF•5
General Repair Procedures Page REF•8
Fault FindingPage REF•9
Buying Spare Parts & Vehicle Identification Numbers PageREF•12
Glossary of Technical Terms PageREF•13
IndexPage REF•17
Contents

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

Fig. 1.20 Flywheel housing cover plate
removed (Sec 13)
Fig. 1.19 Left-hand flexible
mounting (Sec 13)
10Disconnect the leads from the reversing
lamp switch.
11Disconnect the coolant hoses from the
cylinder head and coolant pump.
12Disconnect the fuel inlet hose from the
fuel pump. Plug the hose.
13Disconnect the throttle and choke
controls from the carburettor.
14Disconnect the heater hoses from the
engine.
15Disconnect the fuel return hose from the
carburettor.
16Disconnect the exhaust downpipe from
the manifold.
17Raise the front end of the car and support
it securely on axle stands. Remove the
roadwheels.
18Unscrew the driveshaft to hub nuts. These
are very tight and a long knuckle bar will be
required when unscrewing them. Have anassistant apply the brakes hard to prevent the
hub turning.
19Working under the car, remove the
protective shields and disconnect the exhaust
system mountings and withdraw it to the
rear.
20Disconnect the forward ends of the
gearchange rods by prising their sockets from
the ballstuds.
21Unscrew the nuts on the steering tie-rod
end balljoints and using a suitable “splitter”
tool separate the balljoints from the steering
arms. Unbolt the brake calipers and tie them
up out of the way.
22Unscrew and remove the bolts which
secure the hub carriers to the U-clamps at the
base of the suspension struts (photo).
23Pull the tops of the hub carriers from the
clamps and release the driveshafts from the
hub carriers.24Tie the driveshafts in a horizontal plane
with lengths of wire.
25Support the engine on a hoist or use a
trolley jack under the engine/transmission and
remove the bottom mounting and then the
upper left and right-hand ones (photo).
26Carefully lower the power unit to the floor
and withdraw it from under the car.
27External dirt and grease should now be
removed using paraffin and a stiff brush or a
water-soluble solvent.
28Unbolt and remove the engine mounting
brackets and the starter motor.
29Unbolt and remove the cover plate and
gearchange ball stud strut from the lower front
face of the flywheel housing.
30With the engine resting squarely on its
sump pan unscrew the flywheel housing
connecting bolts noting the location of any
lifting lugs and hose and wiring brackets.
1•14 903 cc engine
13.25 Right-hand engine mounting
Fig. 1.18 Hub carrier detached
from strut clamp (Sec 13)
13.22 Hub carrier strut clamp
Fig. 1.17 Tie-rod end balljoint
disconnected (Sec 13)Fig. 1.16 Gearchange rods
disconnected (Sec 13)
Fig. 1.15 Fuel return hose
disconnected from carburettor
(Sec 13)Fig. 1.14 Fuel inlet hose
disconnected from pump
(Sec 13)Fig. 1.13 Coolant hose at rear
of coolant pump (Sec 13)Fig. 1.12 Coolant hoses at
thermostat housing (Sec 13)

from the suspension struts and then remove
the bolts which secure the hub carriers to the
U-clamps at the base of the suspension
struts.
23Pull the tops of the hub carriers down and
then outwards and push the driveshafts from
them.
24Unbolt the driveshaft inboard boot
retainers and then remove the driveshafts
from the transmission.
25Support the engine on a hoist or use a
trolley jack under the engine/transmission.
Remove the bottom mounting and then the
upper left and right-hand ones.
26Lower the power unit to the floor by
pushing it to the left-hand side to clear the
right-hand mounting bracket and then swivel
the gearbox towards the rear of the car.
Withdraw the engine/transmission from under
the car.
27External dirt and grease should now be
removed using paraffin and a stiff brush or a
water-soluble solvent.
28Unbolt and remove the engine mounting
brackets and the starter motor.
29Unbolt and remove the cover plate with
the gearchange ball stud strut from the lower
front face of the flywheel housing.
30With the engine resting squarely on its
sump pan, unscrew the flywheel housing
connecting bolts, noting the location of any
lifting lugs and hose and wiring clips.
31Support the weight of the transmission
and withdraw it in a straight line from the
engine.
36 Engine- dismantling (general)
Refer to Section 14, Part 2.
37 Engine ancillary components
- removal
Refer to Section 15, Part 2 and also remove
the intake manifold.
38 Engine-
complete dismantling
3
1Have the engine resting squarely and
supported securely on the work surface.
2Unbolt and remove the timing belt cover.
3Grip the now exposed timing belt with the
hands and loosen the camshaft sprocket.
4Release the timing belt tensioner pulley
centre bolt, then slip the belt from the pulley
and sprockets to remove it. Note which way
round the belt is fitted, usually so that the
lettering on the belt can be read from the
crankshaft pulley end of the engine.
5Remove the camshaft sprocket.6Unbolt and remove the camshaft timing belt
cover backing plate.
7Unbolt and remove the camshaft carrier
cover.
8Unbolt the camshaft carrier and lift it off
very slowly, at the same time pushing the cam
followers and their shims down with the
fingers securely onto their respective valve
springs. It is easy to remove the camshaft
carrier too quickly with some of the cam
followers stuck in it and as the carrier is lifted
away, the cam followers will fall out. If this
happens, the valve clearances will be upset as
the cam followers and shims cannot be
returned, with any certainty, to their original
positions. Keep the cam followers and shims
in their originally fitted order.
9Unscrew and remove the cylinder head
bolts and nuts, grip the manifold, rock the
head and remove the complete cylinder
head/manifold/carburettor assembly. Remove
and discard the cylinder head gasket.
10Unbolt the coolant pump from the side of
the cylinder block and remove it complete
with coolant distribution pipe. Remove the
crankcase breather.
11Remove the distributor/oil pump
driveshaft. This is simply carried out by
inserting a finger into the hole vacated by the
distributor and wedging it in the hole in the
end of the driveshaft. Lift the shaft out of
mesh with the auxiliary shaft. Where the
distributor is driven by the camshaft, a cover
plate retains the oil pump driveshaft in
position.
12Unbolt and remove the sprocket from the
end of the auxiliary shaft. The sprocket is held
to the shaft with a Woodruff key.
13Unbolt the auxiliary shaft retainer and
withdraw the shaft from the crankcase.
14Unscrew and remove the crankshaft
pulley nut. This is very tight and the flywheel
starter ring gear will have to be jammed with a
cold chisel or a suitably bent piece of steel to
prevent the crankshaft rotating.
15Withdraw the crankshaft sprocket, which
is located by the Woodruff key.
16Unbolt the front engine mounting bracket
from the cylinder block, together with the
timing belt cover screw anchor bush. Unbolt
and remove the timing belt tensioner pulley.
17Unscrew the flywheel securing bolts. Thestarter ring gear will again have to be jammed
to prevent the crankshaft rotating as the bolts
are unscrewed. Mark the flywheel position in
relation to the crankshaft mounting flange,
then remove it.
18Unbolt the front and rear crankshaft oil
seal retainer bolts from the crankcase and the
sump. Remove the oil seal retainers.
19Turn the engine on its side, extract the
remaining sump bolts and remove the sump.
If it is stuck, try tapping it gently with a
soft-faced hammer. If this fails, cut all round
the sump-to-gasket flange with a sharp knife.
Do not try prising with a large screwdriver; this
will only distort the sump mating flange.
20With the sump removed, unbolt and
remove the oil pump.
21Grip the oil pick-up pipe and twist or rock
it from its hole in the crankcase. It is an
interference fit in the hole.
22Remove the piston/connecting rods as
described in Section 32.
23Before unbolting the main bearing caps,
note that they are marked with one, two, three
or four notches. No. 5 main bearing cap is
unmarked. Note that the notches are nearer
the auxiliary shaft side.
24Unbolt and remove the main bearing
caps. If the bearing shells are to be used
again, tape them to their respective caps. The
bearing shell at the centre position is plain,
the others have a lubricating groove.
25Carefully, lift the crankshaft from the
crankcase, noting the thrust washers at No. 5
main bearing. These control the crankshaft
endfloat.
39 Cylinder head- dismantling
and decarbonising
4
1The operations are similar to those
described for the ohv engine in Section 17 in
respect of decarbonising and valve grinding.
2To remove a valve, use a valve spring
compressor to compress the first valve and
then extract the split collets (photo).
3Release the valve spring compressor.
4Withdraw the valve spring cap and the
double valve springs (photos).
5Remove the valve (photo).
1•28 1116 cc and 1301 cc engine
39.4A Valve spring cap39.2 Valve spring compressor and split
collets

2Draw the engine and transmission together
by screwing in the connecting bolts.
Refit lifting lugs and hose and wiring clips
(photo).
3Bolt the lower cover plate to the face of the
flywheel housing.
4Bolt the starter motor into position.
5Bolt the mounting brackets into place.
6Place the engine/transmission on the floor
ready for raising by hoist or jack into the
engine compartment.
7Raise the car and position it over the
engine/transmission.
8Hoist or jack the power unit upwards until
the left and right-hand mountings can be
connected (photos).9Remove the lifting mechanism and connect
the bottom mounting (photos).
10Connect the inboard ends of the
driveshafts with the transmission and the
outboard ends with the hub carriers.
11Reconnect the hub carriers with the
clamps at the base of the suspension struts.
Tighten the fixing bolts to the specified torque.
12Bolt the brake flexible hose support clips
to the suspension struts.
13Reconnect the tie-rod end balljoints
tightening the nuts to the specified torque.
14Reconnect the gearchange rods. The
easiest way to do this is to force the sockets
onto the ball studs using a pair of self-locking
grips (photo).15Refit the exhaust system and
reconnect the downpipe to the manifold
(photo).
16Screw on the driveshaft nuts and tighten
them to the specified torque. Have an
assistant apply the brake pedal hard to
prevent the driveshaft from turning.
17Refit the front roadwheels and lower the
car to the floor.
18Reconnect the carburettor fuel and
coolant hoses.
19Unplug the fuel hose and connect it to the
pump.
20Reconnect the choke and throttle controls
to the carburettor.
21Reconnect the coolant and heater hoses
1116 cc and 1301 cc engine 1•33
44.8B Left-hand engine mounting44.8A Raising engine/transmission into
engine compartment44.2 Lifting lug at bellhousing bolt
44.15 Exhaust downpipe flange nuts44.14 Connecting a gearchange rod ball
cup44.9B Lower mounting attachment bolts
44.9A Engine/transmission lower mounting44.8D Right-hand mounting bolted up44.8C Right-hand engine mounting
brackets
1

fluid. They are “sealed”. Liquid will get in, but
a thorough clean will be impracticable, and it
will be impossible to get new grease in.
17Check all the parts, get a new gland, two
new grommets, (1116 cc and 1301 cc) and a
new gasket. Scrape all deposits out of the
housing and off the impeller.
18To reassemble, start by inserting the new
grommets (1116 cc and 1301 cc) in the
grooves by each bearing. Fit the circlip to the
shaft, then the shouldered ring, bearings and
spacer. Fit the shaft and bearing assembly
into the cover. Fit the stop screw. Press on
the pulley.
19Fit the new gland (seal), seating it in its
location in the cover. Press the impeller onto
the shaft. The impeller must be put on part
way, and then the housing held in place to see
how far the impeller must go down the shaft
to give the correct clearance, which is 0.8 to
1.3 mm (0.03 to 0.05 in) as shown in Figs. 2.4
and 2.5.
20The impeller clearance can be checked
through the coolant passage in the side of the
pump.
21Refitting is a reversal of the removal
process, but use a new flange gasket and
tension the drivebelt as described in Section 8
(photo).
22Refill the cooling system.
10 Cooling system sensors
1A coolant temperature sender switch is
located in the cylinder head (above No. 1
spark plug) on 903 cc engines and adjacent to
No. 2 spark plug on 1116 cc and 1301 cc
engines.
2The switch operates the coolant
temperature gauge and an excessive
temperature warning lamp.
3On some models, a level sensor is screwed
into the side of the expansion tank. This
sensor consists of a pair of reed switches
within a capsule which are kept closed by the
strong magnetic flux generated by the
hydrostatic force inspired by the action of the
coolant against the float.
4If the coolant level drops then the magneticflux is weakened and the switches open.
5In the event of a fault developing, before
assuming that the cause is the sensor, check
all connecting wiring.
11 Heating and ventilation
system- description
1The heater is centrally mounted under the
facia and is of fresh air type.2Air is drawn in through the grille at the base
of the windscreen. It then passes through the
coolant heated matrix when it can then be
distributed through selective outlets
according to the setting of the control levers.
3A booster fan is provided for use when the
car is stationary or is travelling too slowly to
provide sufficient air ram effect.
4Fresh air outlets are provided at each end
and centrally on the facia panel.
12 Heater unit-
removal and refitting
1
1Drain the cooling system.
2Disconnect the heater hoses at the engine
compartment rear bulkhead.
3Working within the car under the facia
panel, disconnect the leads from the
heater blower by pulling the connecting plug
apart.
4If a radio is fitted, disconnect the
aerial, earth, speaker and power leads from
it.
Cooling and heating systems 2•5
Fig. 2.6 Checking impeller clearance
(Sec 9)9.21 Fitting coolant pump (1116 cc engine)
Fig. 2.7 Heater and ventilation system (Sec 11)
A Fresh air inlet flap
B Air distribution flap
C Coolant valveD Blower
E MatrixF Control levers
G Footwell air duct
2

pump jet and give ten full strokes of the
throttle lever, pausing between each stroke to
allow fuel to finish dripping.
8The total volume of fuel collected should be
between 2.5 and 4.5 cc. Adjust the nut on the
pump control and if necessary to increase or
decrease the volume of fuel ejected.
Fast idle adjustment
9With the choke valve plate fully closed, the
throttle valve plate should be open to give a
dimension (X) (Fig. 3.18) of between 0.90 and
1.0 mm (0.035 to 0.039 in). Use a twist drill of
suitable diameter to measure the gap. If
necessary, adjust by means of the screw and
locknut.
Anti-flooding device
10Close the choke valve plate by means of
the control lever. At the same time, push the
lean out valve rod towards the valve.
11There should be a gap (X) (Fig. 3.19)
between the edge of the choke valve plateand the carburettor throat of between 4.75
and 5.25 mm (0.187 to 0.207 in). Adjust if
necessary by means of the screw and locknut
on the lean out valve.
11 Carburettors (Weber 32 ICEE/
250 and Solex C32 DISA 14)-
description and adjustment
4
1One of these carburettors is used on
903 cc ES engines. They are very similar to
the Weber 32 ICEV 50/250 and Solex
C32 DISA 11 already described in this
Chapter except that a fuel cut-out solenoid
valve is fitted in association with the Digiplex
ignition system (see Chapters 4 and 9).
2The solenoid valve cuts off the supply of
fuel to the carburettor whenever the
accelerator pedal is released during overrun
conditions.
3A fuel cut-out device control unit receives
information regarding engine speed from the
static ignition control unit.
4A throttle butterfly switch relays informationthat the accelerator pedal is in the released
state.
5At certain minimum idle speeds during
deceleration, the fuel cut-out solenoid valve is
re-energised so that engine idling is
maintained without the tendency to cut out.
6The Solex type control unit varies the fuel
cut-out point according to the deceleration
value.Fault testing
7Should a fault develop, connect a test lamp
between the fuel cut-out solenoid switch and
a good earth.
8Connect a reliable tachometer to the engine
in accordance with the maker’s instructions.
9Start the engine and raise its speed to
between 3000 and 4000 rev/min, then fully
release the accelerator pedal.
10The test lamp should only go out during
the period when the accelerator pedal is
released. Should the test lamp remain on all
the time, or never come on, check the throttle
switch earth and the solenoid switch
connections.
11Disconnect the multi-plug from the control
unit. Switch on the ignition and check that a
test lamp connected between contact 7 of the
multi-plug and earth will illuminate. If it does
not, there is an open circuit from connection
15/54 of the fuel cut-off switch.
12Switch off the ignition and check for
continuity between contact 3 of the multiplug
and earth. An ohmmeter will be required for
this test.
13If there is no continuity (ohmmeter shows
infinity), check all the system earth
connections. Also check that the wiring plug
under the control unit is properly connected.
14Finally, check the engine speed signal. To
do this, a tachometer must be connected to
the single socket under the control unit within
the engine compartment.
15If the tachometer registers correctly then
this confirms that the electronic ignition
Fuel system 3•9
Fig. 3.18 Fast idle adjustment diagram (Solex C32 DISA 11)
(Sec 10)
X = 0.90 to 1.0 mm (0.035 to 0.039 in)Fig. 3.19 Anti-flooding device adjustment diagram
(Solex C32 DISA 11) (Sec 10)
X = 4.75 to 5.25 mm (0.187 to 0.207 in)
Fig. 3.21 Sectional view of fuel cut-off
switch (Solex C32 DISA 14) (Sec 11)
Fig. 3.20 Moving lean out valve rod
(Solex C32 DISA 11) (Sec 10)
X = 4.75 to 5.25 mm (0.187 to 0.207 in)
3