Q: How to adjust the Headlight on Mercury Mariner?
A: The headlights must be aimed correctly. If adjusted incorrectly they could blind the driver of an oncoming vehicle and cause a serious accident or seriously reduce your ability to see the road. The headlights should be checked for proper aim every 12 months and any time a new headlight is installed or front end body work is performed. It should be emphasized that the following procedure is only an interim step that will provide temporary adjustment until the headlights can be adjusted by a properly equipped shop. The vertical adjustment screws are located behind each headlight. There are no horizontal adjustment screws. There are several methods for adjusting the headlights. The simplest method requires masking tape, a blank wall and a level floor. Position masking tape vertically on the wall in reference to the vehicle centerline and the centerlines of both headlights. Position horizontal tapeline in reference to the centerline of all the headlights. It may be easier to position the tape on the wall with the vehicle parked only a few inches away. Adjustment should be made with the vehicle parked 25 feet from the wall, sitting level, the gas tank half-full and no heavy loading the vehicle. Starting with the low beam adjustment, position the high intensity zone so it is two inches below the horizontal line. Adjustment is made by turning the adjusting screw clockwise to raise the beam and counter-clockwise to lower the beam. With the high beams on, the high intensity zone should be vertically centered with the exact center just below the horizontal line. It may not be possible to position the headlight aim exactly for both high and low beams. If a compromise must be made, keep in mind that the low beams are the most used and have the greatest effect on safety. Have the headlights adjusted by a dealer service department or service station at the earliest opportunity.