Page 316 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

3
Electrical systems 299

+ +

+

Figure 3.92 Switch positioned in the door pillar
K

3.3.3 Interior lighting
Figure 3.93 Circuit for interior lights
Interior lighting consists of several systems, the main ones being courtesy lights,
map lights and panel illumination lights. Features such as delay and fade-out
are now common. This requires some electronic control. Map lights are an extra
feature to assist with reading a map in the dark. Many types are available: some
are small spotlights, which form part of the interior light assembly, while others
are positioned on the centre console of the vehicle.
Lights are designed to illuminate the vehicle interior when the doors are opened.
Most cars have one central interior light above the rear-view mirror, or two lights,
on the sides above the driver’s and passenger’s shoulders. Door switches are
simple spring-loaded contacts that are made as the door opens ( Fig. 3.92 ). The
contacts are broken again as the door closes. Rubber seals are sometimes used
to keep water out. The same switches may also be used for the alarm system.

The circuit shown in Fig. 3.93 is typical of many in common use. The sliding
switches have three positions: ‘off’, ‘on’ and ‘door operated’. The control module
is to allow delay operation. In this case, it is also used for the central locking
system.
Panel and instrument lights are illuminated when the vehicle sidelights are
switched on. Most cars also incorporate a dimmer switch so the level of
illumination can be set.
Interior lights are important for passenger comfort. Most now operate via some
type of electronic control. One enhancement is a switching-off delay, after the
doors are closed. Some manufacturers are linking functions such as interior
lights with other systems, by a central control module.

3.3.4 Lighting circuits

Lighting circuits can appear complex at fi rst view. However, if you concentrate
Key fact
on just one part of the circuit at a time you will fi nd it easier to understand.
Relays are often used because they take load off the control switches. They are Relays take the load off control
still simple switches, so don’t panic! Take your time and you will fi nd electrical switches.
circuits an interesting challenge.
The diagram shown in Fig. 3.94 is the complete lighting circuit of a vehicle.
Operation of the switch allows the supply on the N or N/S wire to pass to fuses