Here's a general procedure, but always consult your owner's manual for the precise instructions and diagrams specific to your 1979 Cadillac Seville:
1. Park on a level surface: Ensure the car is parked on a flat, level surface at least 25 feet away from a wall or screen. This is crucial for accurate adjustment.
2. Turn on the headlights: Turn on your headlights (low beams) so you can see the beam pattern.
3. Locate the adjustment screws: The adjustment screws are usually located behind the headlight assembly. You might need to:
* Remove the grill: This is likely necessary to reach the screws. Carefully remove the grille (check a repair manual for the specific steps).
* Access from behind the headlight assembly: Some access may be possible from the back of the headlight assembly once the grille is removed. Look for two screws per headlight; one adjusts the vertical aim (up and down), and the other adjusts the horizontal aim (left and right).
4. Identify the adjustment screws: There will be two adjustment screws for each headlight:
* Vertical Adjustment: This screw controls the up-and-down aim of the headlight beam.
* Horizontal Adjustment: This screw controls the left-and-right aim of the headlight beam.
5. Adjust the headlights: Use a small screwdriver (likely Phillips or flathead, depending on your car) to carefully turn the adjustment screws.
* Turning the vertical adjustment screw clockwise will raise the beam, and counterclockwise will lower it.
* Turning the horizontal adjustment screw clockwise will move the beam to the right, and counterclockwise will move it to the left.
6. Check the beam pattern: After each adjustment, turn off and then back on the headlights to check the beam pattern on the wall. The ideal beam pattern should be slightly below horizontal at the point where the headlights meet the wall, and should follow a fairly consistent line from center to edge. The owner's manual should give a detailed diagram.
7. Repeat as needed: Continue adjusting until the beam pattern is correct for both headlights. Make small adjustments, check, and then readjust.
8. Reassemble: Carefully put everything back together, including the grill.
Important Considerations:
* Owner's Manual: The most important resource is your 1979 Cadillac Seville owner's manual. It will have the specific instructions and diagrams for your vehicle.
* Repair Manual: A repair manual (like a Haynes or Chilton manual) can be very helpful for detailed instructions on removing the grill and accessing the headlight adjustment screws.
* Professional Help: If you're unsure about any part of this process, it's best to take your car to a qualified mechanic. Incorrect headlight adjustment can be dangerous.
Remember to be patient and make small adjustments at a time to achieve the correct beam pattern. Safety is paramount; correctly aimed headlights are essential for safe driving at night.
