Regarding Edward Lapham's July 5 column, "Warning! I brake for dim bulbs": Some technical information might help him better understand the taillight situation on Chevrolet TrailBlazers and GMC Envoys.
The implication in his column is that the light bulb has burned out. In fact, those vehicles use a light-emitting diode array as opposed to the usual light bulb, and LED arrays simply do not burn out.
An LED array is driven by a small circuit board, and apparently, that circuit board is prone to premature failure and is being replaced by General Motors under warranty.
The visible light frequency spectrum of the red LEDs used in those taillights includes the same frequency used in laser-based speed detectors, so following a TrailBlazer or Envoy will set off your laser detector every time the brake is applied.