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► Incandescent lamps consist of one or more filaments, which heat up until they glow.
► Halogen lamps have a much longer life and are generally brighter and produce more light per unit of power consumed, but they become very hot during use.
► High-intensity discharge (HID) headlamps produce light with an electric arc rather than a glowing filament.
► Light-emitting diodes (LEDs) have been used for some time in various automotive applications, such as warning indicators and alphanumeric displays.
► One of the advantages of LEDs is that they turn on instantly.
► All lamps or light bulbs have letters and numbers stamped on them that indicate the power consumed by bulb operation at the nominal operating voltage.
► Lighting regulations should always be consulted before modifying or adding to any of the vehicle lighting systems.
► Park, tail, and marker lamps are all low-intensity or low-wattage lamps used to mark the outline or width of the vehicle.
► Brake lights, which may also be called stop lights, are red lights mounted to the rear of the vehicle.
► Reverse lights, also called back-up lights, are the bright white lights on the back of the vehicle that allow the operator to see behind the vehicle when backing up.
► Hazard lights can warn other road users that a hazardous condition exists or that the vehicle is standing or parked in a dangerous position on the side of the road; they normally use the same bulbs as the turn signal indicators.
► The dim or low beam is usually set to the outside of the front, and the high beams are closer to the front center of the vehicle.
► The driving lights are installed on the front of the vehicle and provide higher intensity illumination over longer distances than standard headlight systems.
► Different lighting technologies can be mounted individually, or together, to form comprehensive adaptive lighting systems, otherwise known as smart lighting.
► Auto-leveling headlights use a sensor to monitor the angle of the vehicle to the road.
► In some vehicles, an ambient light sensor determines when light levels are low; this then allows the body control computer to turn the exterior lights on.
► Networking, CAN-bus, or multiplexing light systems eliminate the amount of wire required for the lighting system and are controlled through a main computer.
► Warning lamps provide the vehicle operator with information regarding the operation of the main vehicle systems, such as the vehicle battery charge, oil pressure level, and airbag system status.
► A typical lighting circuit is made up of the battery, fuses or circuit breakers, switches, lamps, and wiring to connect the electrical circuit.
► For motor vehicles and trailers, two red tail lamps operate when the headlight switch is in the park position and the headlight position.
► Daytime running lights (DRLs) automatically operate when the vehicle is running and turn off when the engine stops.
► The layouts of electrical circuits and their components are shown as diagrams made up of symbols and connecting lines.
► Being able to read and interpret electrical circuit layouts can cut a technician’s troubleshooting time in half; this is a skill all technicians need to learn.
► When checking lighting and peripheral systems, be sure to work in a systematic manner or you could miss a faulty bulb or other component.
► If all of the bulbs on one fuse do not work, check the fuse.
► When replacing a bulb, always ensure there is no corrosion in the bulb socket, as this will shorten the life of the new bulb and add resistance in the circuit.
► Always make sure you replace a bulb with one of exactly the same type.
► It is critical that headlights be aimed correctly so as not to impair an oncoming vehicle and to allow correct visibility for the driver.