WHILE BACKING OUT OF A PRIVATE DRIVEWAY ONTO A PUBLIC STREET AND NEARING THE END OF MY REVERSING I HIT THE BRAKES AND USING THE ROTARY GEAR SELECTOR SELECTED "D" FOR DRIVE, THE "D" ILLUMINATED AND BEGAN BLINKING THINKING THE VEHICLE WAS IN DRIVE I LOOKED AHEAD OF ME TO PROCEED FORWARD BUT THE TRUCK CONTINUED TO ROLL BACKWARDS AND STRUCK A PARKED CAR. I HAVE SINCE NOTICED THAT THE GEAR SELECTOR UNDER CERTAIN CONDITIONS WILL SHOW IT IS IN "D" "R" OR "P" WHEN IN FACT IT BLINKS AND THAT GEAR IS NOT SELECTED.