A precision light source, such as a laser, controlled by the operation of a garage door opener to generate a light beam to provide a reference mark for guiding a user in parking a vehicle. One embodiment teaches powering the unit from the light activation circuitry of the garage door opener directly, or using a bulb connection base having an auxiliary light socket. Further improvements include the use of an aiming device providing dimensional adjustment of the light beam to move the distal reference point created when the light beam intersects the vehicle. A method for use of the apparatus is also taught.