1966 FIAT 500 horn connection

CHAPTER 11
THE ELECTRICAL EQUIPMENT
11:1 Description
11:2 Battery
11:3 The generator
11:4 The starter
11:5 The control box
1 1 : 6 Fuses
1 1 : 7 Flasher unit
11:1 Description
All models covered by this manual have 12 volts
electrical systems in which the negative battery terminal
is earthed. There are three units in the regulator box to
control the charging circuit; a cut-out, a current regulator
and a voltage regulator. These are adjustable but it must
be stressed that accurate moving coil meters are required
when checking or altering the settings. Cheap and
unreliable instruments will make accurate adjustments
impossible.
There are wiring diagrams in Technical Data at the end
of this manual to enable those with electrical experience
to trace and correct wiring faults.
For t h e U.K. Market the headlamps are of the double
filament dipping renewable bulb type with adjustments
for individual beam settings.
The battery is located in the front compartment
forward of the petrol tank and the fuses to the rear o f the
petrol tank.
Detailed instructions for servicing the electrical equip-
ment will be found in this chapter, but it must be pointed
out that it is not sensible to try to repair that which is
seriously defective, electrically or mechanically. Such
equipment should be replaced by new units which can
be obtained on an exchange basis.
F500111
11 :8 Windscreen wipers
1 1 : 9 The lighting system
11:10 Panel and warning lights
11:11 The horn
11:12 Lighting and flasher switch
1 1 : 1 3 Fault diagnosis
11.2 The battery
This of the 12-volt lead/acid type and has to meet
heavy demands for current particularly in the winter. To
maintain the performance of the battery at its maximum
it is essential to carry out the following operations.
Keep the top of the battery and surrounding parts dry
and clean, as dampness can cause leakage between the
securing clamps and the battery terminals. Clean off any
corrosion from the metal parts of the battery mounting
with diluted ammonia and paint them with an anti-
sulphuric paint. If the terminal posts are corroded,
remove the cables and clean w i t h diluted ammonia.
Smear the posts w i t h petroleum jelly before remaking the
connections and fit the terminals securely. High electrical
resistance due to corrosion at the terminal posts is often
responsible for lack of sufficient current to operate the
starter motor.
Ensure t h a t the filler plugs are in good condition and
show no signs of cracks. This may cause leakage of
electrolyte and consequent corrosion. Test the condition
of the cells after topping-up the electrolyte level with
distilled water to just above the tops of the separators as
shown in FIG 11 :2 . Never add neat acid. If it is
necessary to make a new electrolyte due to loss by
spillage add sulphuric acid to the
distilled water.
It is highly dangerous to add water to acid.

Lamp brilliance varies w i t h the speed of t h e car:
Check the condition of the battery. Examine the battery
connections. Make sure they are tight and renew faulty
cables.
11:10 Panel and warning lights:
All the gauges are clustered in a single instrument
mounted on the dashboard above the steering column.
Incorporated in this cluster is the parking light pilot light,
generator charge indicator, fuel reserve supply indicator,
low oil pressure indicator, and the speedometer w i t h
mileage recorder.
The parking lamp indicator glows green when the
ignition lock switch key is in either position 1 or 2 once
the toggle switch on the instrument panel has been
operated.
The generator charge indicator shows red only when
the ignition is turned on. It should be extinguished when
the generator output is sufficient for battery charge
(12.6 ± 0.2 volts) with the engine running at a speed
of 1100 rev/min and the headlights switched off.
The fuel reserve supply indicator shows red only when
the ignition is turned on and the amount of fuel in the
petrol tank has dropped to approximately .8 to 1.1
Imp. gallons.
The low oil pressure indicator shows red only when the
ignition is turned on and should be extinguished when
the oil pressure reaches 7.1 to 21.3 Ib/sq in, and opens
the sending unit contacts. Once the engine is at normal
operating temperature but at a speed below 1000 rev/
min the indicator might light up even the pressure is under
control and with normal operation.
All the bulbs fitted to the above described units are of
the tubular 2.5W type and to renew a bulb extract the
bulb holder from the rear of t h e instrument cluster and
release the bulb which is attached by a normal bayonet
coupling.
Fuel reserve supply indicator sender u n i t:
The fuel reserve supply indicator should be checked for
correct indication by allowing the fuel tank to empty and
then inserting .8 to 1.1 Imp. gallons at which stage the
light should extinguish. Any failure to do so should be
checked as follows:
1 Ensure that the indicator bulb operates correctly.
2 Check for complete circuit between the sender unit and
the indicator bulb.
3 If the sender unit float bracket is distorted the bulb
will
indicate a reserve supply of fuel greater or smaller than
specified. The bracket should be adjusted to give
correct indication of fuel level.
4 The sender unit could have been inadvertantly
damaged in which case the unit must be renewed.
11 :11 The horn
The horn circuit comprises the horn, push button at the
centre of the steering wheel and normal earth return
electrical circuit through the car body. One terminal is
connected to the battery whilst the other to the push
button on the steering wheel which when the button is
depressed the circuit will be closed so causing the horn
to operate.
F500
FIG 11 : 21 Number plate lamp
Key to Fig 11 : 21 A Lens and light cap mounting screws
B Lens
FIG 11 : 22 Horn (opened)
Key to Fig 11:22 1 Body 2 Diaphragm 3 Armature
4,5,6 Core 7 Cable: terminal-condenser-stationary contact
8 Cable: terminal-magnetizing coil end 9 Magnetizing coil
FIG 11 :23 Horn sound adjustment. Obtained by adjust-
ing the armature air gap
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Before removing an apparently faulty horn check the
wiring and connections. Check that the mounting bolts
are tight and that the horn does not foul any adjacent part.
Removal and installation:
This is a straightforward operation and the only
precaution to be taken is to ensure that the rubber gasket
bonded to the horn body does not become detached. If
the horn is renewed, before installing the new horn bond
the rubber gasket to the new unit with adhesive in
the same position as was on the original horn unit fitted.
Should the horn fail to operate the following points
should be noted.
1 Damaged horn.
2 Broken connection between battery and horn.
3 Broken connection between horn and push button on
steering wheel
4 Damaged push button mechanism.
5 Directional signal and outer lighting changeover
switch blade contact failing to make contact with the
steering wheel hub ring contact.
6 Current lead displaced from the horn blade contact on
the directional signal and outer lighting switch.
7 Distorted or broken diaphragm in horn.
8 Connections or inner windings
broken or burnt.
9 Electro-magnet contact points dirty or excessively
worn.The contacts may be adjusted by the adjusting screw
after the points have been cleaned and refaced.
To adjust the tone of the horn use a ring spanner and
screwdriver as shown in FIG 11 :23.
It is recommended that if the horn unit operation is
unreliable a new unit should be fitted rather than the
original one repaired.
11:12 Lighting and flasher switch
Description:
The two switches provide a directional signal switch
which automatically returns to the rest position once a
turn has been negotiated and the steering wheel is
brought back to the straight-ahead position. The change
over switch controls the outer lights and the headlights
flasher. The complete unit is located under the steering
wheel on the steering column.
Switch unit removal:
1 Carefully pry off the horn push button at the steering
wheel centre using a fine blade screwdriver.
2 Disconnect the positive terminal of the battery.
3 Disconnect the plug in contact in the steering wheel
hub.
4 Unscrew the steering wheel retaining nut from the
inner column and remove the steering wheel from the
shaft.
5 Slacken the bolts securing the steering column support
to the body
6 Remove the plug in contacts from the switch unit
ensuring that their correct location is noted for re-
assembly.7 Remove the switch unit from the steering column.
124
Switch unit installation:
This is the reverse procedure to dismantling. It is
advisable after installation to check that the steering
wheel when in the straight-ahead position and the
directional signal switch lever in neutral, the reference
index on the outer face of the directional signal switch
drum is in line with the index on the steering wheel hub.
This will ensure correct sequence of operation.
11:13 Fault diagnosis
(a) Battery discharged
1 Lighting circuit shorted
2 Terminals loose or dirty
3 Generator not charging
4 Regulator or cut-out units not working properly
5 Battery internally defective
(b) Insufficient charging current
1 Loose or corroded battery terminals
2 Generator driving belt slipping
(c) Battery will not hold a charge
1 Low electrolyte level
2 Battery plates sulphated
3 Electrolyte leakage from cracked casing or top sealing
compound
4 Plate separators ineffective
(d) Battery overcharged
1 Voltage regulator needs adjusting
(e) Generator output low or nil
1 Belt broken or slipping
2 Regulator unit out of adjustment
3 Worn bearings, loose pole pieces
4 Commutator worn, burned or shorted
5 Armature shaft bent or worn
6 Insulation proud between commutator segments
7 Brushes sticking, springs weak or broken
8 Field coil wires shorted, broken or burned
( f ) Starter motor lacks power or will not operate
1 Battery discharged, loose cable connections
2 Starter pinion jammed in mesh with flywheel gear
3 Starter switch faulty
4 Brushes worn or sticking, heads detached or shorting
5 Commutator dirty or worn
6 Starter shaft bent
7 Engine abnormally stiff
(g) Starter motor inoperative
1 Check 1 in (f)
2 Armature or field coils faulty