Page 319 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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Electrical systems 301

7 and 8 on the R wire. The two fuses then supply left lights on an RB wire, and
right lights on an RO wire. The number plate lights are also supplied from here.
When the dip beam is selected, a supply is passed, on a U and UR wire, to the
dim dip unit, which is de-energized. This then allows a supply to fuses 10 and 11
on the OU wire. This supply is then passed to the left light on a UK wire and the
right light on a UB wire. Selecting main beam allows a supply on the UW wire to
the main/dip relay, thus energizing it. A supply is therefore placed on fuses 21
and 22 and hence to each of the headlight main beam bulbs.
When sidelights are on, there is a supply to the dim dip unit on the RB wire.
If the ignition supplies a second feed on the G wire from fuse 1, the unit will
allow a supply from fuse 5 to the dim dip resistor on the NS wire. This continues
on to the dim dip unit on an NG wire. The dim dip unit links this supply to
fuses 10 and 11. These are the dip beam fuses. The supply is therefore passed
to the left light on a UK wire and the right light on a UB wire. When the headlights
are switched on, a supply is made from the light switch to fuse 9 on a U wire.
From this fuse, a supply is sent to the fog light relay contacts on a U wire, and
the rear fog lamp switch on a UR wire. When the fog switch is operated, it sends
a supply on the RY wire to close the relay. The main supply is now fed from the
relay on a UY wire to both rear fog lamps.
Following a circuit diagram is easy after a bit of practice. Think of it as a railway
map that is used to get from A to B. Electricity will only complete the ‘journey’ if
the path is a circuit, i.e. it has a return ticket!

3.3.5 Indicators and hazard lights

Direction indicators (turn signals) have a number of statutory requirements. The
light produced must be amber (or red on the rear of some American cars), but
they may be grouped with other lamps. The fl ashing rate must be between one
and two per second with a relative ‘on’ time of between 30% and 57%. If a fault
develops this must be apparent to the driver by the operation of a warning light

on the dash. The fault can be indicated by a distinct change in frequency of
operation or by the warning light remaining on. If one of the main bulbs fails then
the remaining lights should continue to fl ash perceptibly.
Legislation exists as to the mounting position of the exterior lamps. The rear
indicator lights must be within a set distance of the rear lights and within a
set height. The wattage (power) of indicator bulbs is normally 21 W (Fig. 3.95).
These lights often come under the heading of auxiliaries or signalling. A circuit is

Figure 3.95 Indicator bulb