How to prepare your car for headlight adjustment and the basic steps for adjustment
Photo: Shutterstock

All headlights, regardless of technology, require adjustment. There are many reasons for this: natural wear, frequent driving over bumps, vibrations and impacts with the curb when parking… You can adjust the headlights yourself

How to prepare your car for headlight adjustment and the basic steps for adjustment – in the instructions with expert advice.

What is headlight adjustment?

Headlight adjustment is a procedure for adjusting the angle and direction of the light flow of the car’s headlights. It is performed both with the help of special equipment at a service station and independently through simple manipulations. The main indicator taken into account during adjustment is the angle of incidence of the light beam.

Each brand and model has its own and depends on the clearance, type, shape and location of the headlights. As a rule, it is from 1 to 1.3%. The exact information is usually indicated in the car’s operating manual, directly on the plastic headlight or on a sticker under the hood.

Manual adjustment should not be confused with the operation of the corrector, which is located in the car’s interior, usually to the left of the steering rack. In shape, it is a wheel or a switch with a scale. Correctors can be electric or hydraulic. They are used by selecting one of the values, depending on the load of the car (when passengers are sitting in the back and the trunk is loaded).

This can be done directly while driving. Headlight adjustment allows you to correct its geometry, which is disturbed for many reasons: with age, from frequent driving on potholes and bumps, with mechanical damage, for example, in an accident or impacts when parking on a curb.

If your headlights are out of adjustment, it’s easy to tell. Common symptoms include poor roadside illumination, constant honking and flashing of high beams by oncoming cars, and a feeling that your headlights are shining into the sky. When any of these things happen regularly, it’s almost certainly time to adjust your headlights.

When headlight adjustment is needed

The frequency of checking and adjusting headlights directly depends on natural wear. “The older the car, the more it is susceptible to adjustment loss – body vibration, lamp replacement, etc.

As a rule, checking and necessary adjustments are carried out as part of maintenance, but there are a number of cases when unscheduled adjustment is required:

After an accident . After completing the repair, you need to adjust the light, since it is impossible to completely restore the position of the headlights – every millimeter of displacement of the headlight along the axis leads to a serious change in the light output of the car.

After changing tires or wheels . Firstly, summer and winter tires have different pressure, which means the height of the headlights relative to the ground will change. The same applies to changing wheels to a larger or smaller radius.

After replacing the headlight unit . Each headlight, whether new or used, is adjusted to a specific car.

When loading a car . This applies to the situation when heavy objects are transported in a car, filling the interior and trunk to the brim. If the car is not equipped with an “automatic corrector”, you need to adjust the headlights using the “corrector” which has a gradation from “0” to “3”, where “0” means the car is not loaded, and “3” means it is fully loaded.

When replacing lamps . Such a simple action as replacing lamps may lead to the need for adjustment. This is especially true when an analogue is installed instead of the original part, the expert explains.

How to adjust headlights yourself
 (Photo: Shutterstock)

How to adjust headlights yourself

Checking your headlight settings is not difficult, but it does take time and some special tools:

  • Phillips screwdriver;
  • Masking tape, electrical tape or dark marker;
  • Carpenter’s level;
  • Roulette;
  • A horizontal platform on which a car can be parked;
  • Dark wall (garage door);
  • At least 10 m of free space.

The adjustment process consists of two main stages – vehicle preparation and adjustment. Work is carried out at night, in dry weather, without fog, rain and high humidity.

Preparing the car for headlight adjustment

  • Park your car on a level surface against a dark wall or garage door. Make sure the car is level.
  • Check the tire pressure . It should correspond to the manufacturer’s recommended level, remove excess weight from the passenger compartment and luggage compartment, fill the tank at least halfway. For accuracy of measurements, you can call an assistant who will sit behind the wheel, thereby simulating the daily load.
  • Pre-wash and wipe dry the headlights; there should be no dirt or dust on them.
  • Find out in advance where the headlight adjustment screws are located. Depending on the make and model of the car, their location will vary, but, as a rule, they are easy to get to. Some can be turned manually, others only with a screwdriver or Allen key.

Low beam adjustment

Most often, headlights are adjusted on low beam. This applies to the so-called combined lamps, in which the high beam adjustment occurs automatically after the low beam adjustment, the expert explains. Less often, the work is carried out separately, and in some cases, it may be necessary to adjust the fog lights. Step by step, the process looks like this:

  • Park your car on a level area opposite a dark wall or gate. The distance from the wall to the bumper should be at least 5 m, in some cases up to 10 m.
  • Turn on the low beam. Two characteristic “check marks” will appear on the wall opposite each headlight. These are the so-called refraction angles.
  • Take measurements. First, determine the center of the headlight, namely the bulb or lens, by measuring the height to it from the ground with a tape measure. Then determine the distance between the centers of the two bulbs. Write down both values, as they will be needed for marking.
  • Make markings. Draw a horizontal line on the wall or garage door at a height that corresponds to the distance to the center of the headlight. Mark the center point of one of the headlights with a vertical line. From there, measure the distance to the second center. The result will be a horizontal line with two crosses on the sides.
  • Perform calculations using the value of the angle of incidence of the beam. If it is, say, 1.3%, this means that for every meter the light falls downwards by this amount. In centimeters, this is 1.3 cm per meter or 13 mm. For a distance of 5 m, the calculations look like this: 5 x 1.3 = 6.5 cm. This is how many centimeters you need to lower another horizontal line, and make a finishing mark at the centers of the headlights.
  • Find the adjusting bolts. This may require removing the headlight trim or opening the hood, depending on the vehicle. The bolts can be cleaned and treated with WD-40 beforehand.
  • Adjust the headlights. Turn the horizontal and vertical adjustment screws alternately to shift the refraction angles (the lower points of the check marks) so that they coincide with the points marked in step five.
adjust headlights at service stations
To adjust headlights at service stations, they use special optical-mechanical equipment – ​​a regloscope (Photo: Shutterstock)

Adjusting high beam and fog lights

The adjustment of the high beam (if necessary) and fog lights is similar to the adjustment of the headlights. It is also necessary to take measurements, transfer the centers to the wall or garage door, calculate the control marks and direct the light spots to the marked centers using screws.

When adjusting the fog lights, it is worth remembering that they are below the level of the headlights and the light beams should go strictly parallel to the road – not up or to the side. Unlike others, such lights usually have only one adjustment – up/down.

What if adjusting the headlights didn’t help?
If after adjustment it still seems that the headlights are dim and still do not shine well, then the problem is not in the settings. In this case, you should make sure of the following:

  • The headlight bulb is working properly;
  • The battery or generator provides the correct level of power;
  • The headlight plastic has not turned yellow or cloudy, the inside of the housing is clean.

If the problem is not obvious, it is better to contact professionals. Additionally, it may be necessary to check the “TV” (the frame on which the radiator and headlights are attached) or you will have to put washers under the headlight mount to restore its geometry.

Adjusting headlights with a device

To adjust headlights at service stations, they use special optical-mechanical equipment – a regloskop. The requirements for its operation and, accordingly, for adjusting the lighting devices are specified in GOST .

Adjusting headlights with a device
Photo: Autonews

A professional stand usually consists of:

  • From a support platform on rollers and a vertical stand;
  • Optical camera with lux meter;
  • Display on which the measurement results are displayed.

The process of measuring with such a device looks like this step by step:

  • The car is parked on a level area opposite the screen;
  • The optical chamber is positioned so that the optical axis is on the same axis as the car headlight;
  • To adjust the headlights, the mechanic uses the readings shown on the display.

This adjustment is more precise. The procedure itself does not take much time and costs an average $40 to $50.

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