Lighting Circuits: Summary

The most commonly thought of light circuit is the headlights. But there are many lighting systems in the vehicle. Different types of lamps are used to provide illumination for the systems. The lamp may be either a single-filament bulb that performs a single function, or a double-filament bulb that...

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Interior Lights

A rheostat controls the brightness of the instrument panel lights
Interior lighting includes courtesy lights, map lights, and instrument panel lights. Courtesy Lights FIGURE. Courtesy lights using ground side switches. Courtesy lights illuminate the vehicle's interior when the doors are open. Courtesy lights operate from the headlight and door switches and receive their power source directly from a fused battery connection. The switches...

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Exterior Lights

An example of a two-bulb taillight circuit
When the headlight switch is placed in the PARK or HEADLIGHT position, the front parking lights, taillights, side marker lights, and rear license plate light are all turned on. The front parking lights usually use dual-filament bulbs. The other filament is used for the turn signals and hazard lights. Most taillight...

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Flash to Pass

Flash-to-pass feature added to the headlight circuit
FIGURE. Flash-to-pass feature added to the headlight circuit. Many steering column-mounted dimmer switches have an additional feature called "flash to pass." This circuit illuminates the high-beam headlights even with the headlight switch in the OFF or PARK position. In this illustration, battery voltage is supplied to terminal B1 of the headlight...

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Concealed Headlights

Concealed headlights enhance the vehicle's styling and aerodynamics
FIGURE. Concealed headlights enhance the vehicle's styling and aerodynamics. A vehicle equipped with a concealed headlight system hides the lamps behind doors when the headlights are turned off. When the headlight switch is turned to the HEADLIGHT position, the headlight doors open. Early systems used vacuum-controlled doors. Today most systems use...

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Headlight Switches

(A) Instrument panel-mounted headlight switch. (B) Steering column-mounted headlight swith
The headlight switch may be located either on the dash by the instrument panel or on the steering column. It controls most of the vehicle's lighting systems. The most common style of headlight switch is the three-position type with OFF, PARK, and HEADLIGHT positions. The headlight switch will generally receive...

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Headlights

Sealed-beam headlight construction
There are four basic types of headlights used on automobiles today: standard sealed beam halogen sealed beam composite high-intensity discharge (HID) Sealed-Beam Headlights FIGURE. Sealed-beam headlight construction. From 1939 to about 1975, the headlights used on vehicles remained virtually unchanged. During this time, the headlight was a round lamp. The introduction of the...

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