The low and high beam headlights are switched on by the left lever of the steering column switch 9 (figure 122), if the switch button 8 of the external lighting is fully pressed. The headlights are not switched on directly from the switch, but through auxiliary relays 3 and 4 installed in the mounting block 2. This is done in order to reduce the current flowing through the switch contacts.
Figure 122. Headlight and fog light connection diagram:
1 - headlight unit: 2 - mounting block; 3 - high beam headlight relay; 4 - low beam headlight relay; 5 - instrument cluster with high beam indicator lamps (left) and fog light (right): 6 - fog light switch in rear lights; 7 - ignition switch; 8 - outdoor lighting switch; 9 - headlight switch; 10 - fog lamps in the rear lights.
Regardless of the position of switch key 8, the high beam headlights can be switched on briefly (i.e. to signal with high beam headlights), pulling the steering column switch lever towards you. This is ensured by the fact that voltage to contact "30" of the light signaling switch 9 is supplied directly from the ignition switch 7, bypassing the switch 8.
The high beam in the headlights is controlled by a lamp installed in the instrument cluster 5 (left on the diagram).
The headlight reflector together with the diffuser form an optical element. The inner surface of the diffuser is made in the form of a complex system of prisms that scatter light in the horizontal direction. From the back side, a lamp of the AKG 12-60+55 type is inserted into the optical element. The lamp is halogen, i.e. its bulb is filled with iodine vapor and inert gas. The light output and durability of such a lamp are almost twice as high as conventional ones.
The lamp has two tungsten filaments: one (55 W) for low beam and the other (60 W) for high beam. The high beam filament is in the focus of the reflector, so the high beam rays are concentrated into a narrow beam directed almost parallel to the road and illuminating it well at the maximum distance from the car. The low beam filament is brought forward from the focus of the reflector and partially covered from below by a special metal screen. This is done to limit the spread of light upward.
If you direct the low beam beam at a wall, the light spot will have the shape of an ellipse with the upper half cut off. The upper boundary of the illuminated area in the left part of the spot will pass exactly along the horizontal axis of the ellipse, and in the right part - along the line emanating upward from the center of the ellipse at an angle of 15° to its horizontal axis. This shape of the light beam provides good illumination of the road in front of the car (especially its right side and the shoulder) and reduces the possibility of blinding oncoming drivers.
Some vehicles may be equipped with headlight hydraulic correctors. They are used to adjust the headlight angle from the driver's seat depending on the vehicle load. The hydraulic corrector consists of a master cylinder mounted on the instrument panel, actuator cylinders on the headlights, and connecting tubes. The cylinders and tubes are filled with a special liquid that does not freeze at low temperatures.
The hydraulic corrector handle, located on the instrument panel, changes the fluid pressure in the hydraulic corrector system. Under the action of this pressure, the pistons of the actuator cylinders move and turn the optical elements of the headlights to the required position.
If the vehicle does not have a hydraulic corrector, then plugs are installed on the headlights instead of the actuator cylinders.