Rear position lamps (tail lamps)
Night time vehicle conspicuity to the rear is provided by rear position lamps (also called taillamps or tail lamps, taillights or tail lights). These are required to produce only red light, and to be wired such that they are lit whenever the front position lamps are illuminated—including when the headlamps are on. Rear position lamps may be combined with the vehicle’s brake lamps, or separate from them. In combined-function installations, the lamps produce brighter red light for the brake lamp function, and dimmer red light for the rear position lamp function. The tail and brake light functions may be produced separately and/or by a dual-intensity lamp.
Regulations worldwide stipulate minimum intensity ratios between the bright (brake) and dim (tail) modes, so that a vehicle displaying rear position lamps will not be mistakenly interpreted as showing brake lamps, and vice versa.
Many modern designs use LED lighting sources beginning in 1999 with the Cadillac Deville.