Headlight Aiming HOWTO

unitacx

Veteran Member
Joined
Apr 7, 2006
Location
Alexandria, VA
TDI
2002 golf
HOWTO aim headlights
Background:
There are a number of different lighting standards used:
ECE (E-code)
SAE mechanically aligned (nipple type)- HLB, HOH, and HHB
SAE VOR
SAE VOL
SAE VO or ECE high beam (main beam)

There are differences for each type, but the idea is that the dipped beam should not project up along the center or left (RHR countries). The aim should also accomodate shifts in weight.

OEM AND AFTERMARKET

ECE lights (dipped beam) have a flat top, with the beam cutting upward at an angle on the curb side.
High beam (high beam, ECE, DOT and DOT VO) headlights have a generally oval pattern for both
ECE and DOT. DOT apparently has some restrictions on either direct transmission from the bulb or maximum output, but is otherwise similar to ECE.

The US DOT (SAE) standard for headlights is FMVSS 108. The current standard (2006) specifies the above SAE types.
Essentially the types are:

old mechanical - These have a pattern that resembles a cross between a foglight pattern and a high beam pattern. These had historically been aimed so that the curb side light is aimed forward and down, and the road side light is aimed straight and to the curb.

DOT VOL lights have a more flat pattern, with a raised right (curb side) beam area. The raised beam area has a horizontal top, but is often more diffuse than ECE.

DOT VOR lights have a flat top, with the beam cutting upward at an angle on the curb side.
So essentially the difference between ECE/VOL and VOR is which cut-off line is used for aiming.

A 2004 study by the Certified Automotive Parts Association (US) found that 100% of the aftermarket lights tested failed to meet DOT FMVSS 108 standards. It found that only 10% of OEM lights failed to meet DOT FMVSS 108 standards. Lights tested included TYC and DEPO.

It's difficult to determine whether lights which indicate an "E" standard, or whether the ones marked "SAE" are really E-Code lights. The photos in the 2004 didn't look like E-Code, however.

I have seen some reports of lights that meet both ECE and SAE standards; however at least in reflective optics, expect that SAE lights do not meet ECE standards and vice-versa. In the case of the reflective optics dual lights used on '99-04 Golf, Hella produces an SAE VOL light which has a distinctly US pattern.
Theoretically, it should be possible to construct an ECE standards light which meets SAE standards for VOL lights. This may be the case with projector optics lights. There is a specification difference between twin filament H4 and 9003 reflector optics lights, but this difference is insufficent to change the basic lighting pattern between ECE and DOT. i.e., an H4 bulb doesn't convert your SAE/DOT VOL lights to ECE (E-Code). Hella sells some "harmonized" projector lights but these are not truely DOT/ECE, but rather are a variation of SAE VOL.

Taking a statistical sample of 2 (Golf A4 and Jetta A4), Hella uses SAE/DOT VOL lights. The Hella VOL lights are different from their ECE (E-Code) lights. The Jetta, which uses either a 9003 (or perhaps an H4 or H4/9003) dual filament bulb in the US has DOT markings and no ECE markings on their US market lights. US market Golf A4 lights use H7, H7, whereas ECE lights use H1 in the high beam. The DOT lights are different.

D-I-Y

The "do it yourself" approach is a simple "line up with marks on a wall" procedure but it helps to read at least one set of instructions first.

Basically, the main part of the low beam and the entire fog beam should not rise. Most procedures call for the top of the light to fall over distance. The exception is a peak part (SAE/DOT) or the side angled part (ECE/E-code).

First review a detailed set of instructions for lighting, such as those of your car manual (e.g., Bentley) or Daniel Stern's webpage.
http://www.danielsternlighting.com/tech/aim/aim.html

If you want to try to follow the US DOT procedures, here's how:
http://www.tfhrc.gov/safety/hsis/pubs/04148/appendixa.htm
with further information provided at
http://www.tfhrc.gov/safety/hsis/pubs/04148/index.htm
This is obviously presented for amusement, since it's doubtful anyone could really follow these instructions. (Apparently DOT presumes any body shop or garage with a state inspection certificate can implement their instructions.)
These documents are now Unclassified (not Secret) (See the documentation page, items 19 and 20, of
http://www.tfhrc.gov/safety/hsis/pubs/04148/04148.pdf )

What is not explained by DOT (at least in the Unclassified version) is the meaning of SAE VOL and VOR.
VOL = "visual alignment left". The left, or lower part of the pattern is used for vertical alignment. This is the same as E-code alignment, but the lighting pattern for SAE/DOT lights is different.
VOR = "visual alignment right". The right or upper part of the pattern is used for vertical alignment. This technique of course doesn't work for ECE lights because ECE lights use an angled right portion of the pattern.
VO = center alignment, used for separately aimed high beams.
This applies to ECE (E-code) lights, but can be used with SAE (US DOT) headlights.
Some of these procedures are obviously a lot more complicated and in the case of some lights (e.g., HLB, HOH, and HHB) require elaborate or non-existent equipment. The "D-I-Y" procedures would therefore be preliminary to "proper" adjustment, even though the "proper" adjust is impractical (or impossible) to perform.

The "D-I-Y" Procedure:

1. Determine the appropriate tool. A 6 allen is typical. Do this before you find a wall, since most walls don't supply adjustment tools.

2. Find a level area, where you can face a wall. Ideally you should have a full tank, so that the car is in an aft CG configuration.

3. Measure the height of the center of the light. This can be done by moving the car close to the wall, with a measuring stick, or by identifying a spot on your body (leg). Then mark the wall accordingly (if necessary). Masking tape is good for this. (You may wish to leave the masking tape behind with calibration marks as a form of grafitti.)

4. Back the car away from the wall.

5. Adjust the height of the low beam so that the top of the flat part is slightly below the height of the mark. Use a towel or other obstruction to block the opposite light.

6. With ECE (E-code) lights, you should see a double pattern of two angled upward extensions of the illumination. The apex of the angle should align with the position of the lights. That's the horizontal adjustment. This should also appear on the newer SAE/DOT (VOL and VOR) lights, although less distinctly.

7. If you have a separate foglight adjustment, have the foglight slightly below its origin for below-bumper lights or notably below its origin for grill height fogs.

That's it.

... er, not really.​

8. Leave that 6 mm Allen wrench in the car until you take your first long trip at night. The height will probably be wrong. Fortunately the correction will be obvious.

THREE OTHER INSTRUCTION LINKS:

http://forums.tdiclub.com/showthread.php?t=73710&highlight=headlights+aiming

http://danielsternlighting.com/tech/aim/aim.html - Daniel Stern's instructions (formerly at Richard Sexton's mbz.org which is why there are several broken links to him)

http://faqlight.carpassion.info/hl-aiming.htm (from
http://faqlight.carpassion.info/)

- stan
'00 Golf (Rocketchip II, 520, TT 17 wheels, Valeo ECE lights)
 
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