K6JRF at the mic K6JRF's Page
formerly W6FZC

My Mercedes Benz
S500 Coupe

K6JRF's MB S500 Cpe
(Update: Nov 19, 2007)

Analyze and Troubleshoot "Check Engine" MIL and Electronic Control Units (ECU)!

Coupe Headlights
Last week I thought that I'd check the headlight lamps since they have never been checked since I bought the car. What I found is why this topic is posted. You may want to do some of the things that I did to your coupe's headlights.

Halogen Lamps
When I opened the back side of the main assembly, I removed a 80/100 halogen lamp with a dark blue coating. While it may be 'pretty', this coating serves as a filter allowing the lamp to produce only bluish-white light. Needless to say, it's very inefficient since most of the lamp's output is filtered but what light is produced appears more bluish-white than from a conventional halogen lamp. This doesn't make it better, in fact, the filter causes it to produce LESS light.

Sylvania SilverStar Brightness But this is just the tip of the iceberg. Suffice to say, I did some 'homework' so I could catchup on what's new in halogen lighting for my Mercedes coupe. There's a lot of argument but after looking over the field, I chose the Sylvania 'SilverStar' (SS) lamps, 9003ST. They operate at a very high temperature, around 4000K, which makes the light appear very 'white' and very bright, brighter than PIAA bulbs. Also they are LEGAL (use nominally 55/65 watts) for use in the USA and Canada unlike the ones I removed. There are a lot of lamps that MAY be better but this lamp is available almost everywhere and the cost is reasonable, about $29 for two. Light output for the 9003ST is 910/1500 lumens with maximum wattage 65/72 watts. The bad part is that the lamp's life is relatively short when compared to a conventional lamp.

Sylvania says: "SilverStar halogen products are the newest products in the Sylvania High Performance Line. They are both the whitest and the brightest lights available. SilverStar is whiter light, closer to the color of daylight. Whiter light helps you see better at night and if your night vision is better, night driving is safer".

New Halogen Lamps: Silverstar Ultra
Sylvania SilverStar Ultra Lamp Recently Sylvania has released on new version of their "Silverstar" lamp solution for safer night time driving, called the SilverStar® ULTRA. These provide up to 25% increase in down road visibility, increased side road visibility and up to a 20% brighter light, compared to standard halogen headlights. They also last up to 30 percent longer than regular SilverStar headlights.

The pure, white light emitted by the SilverStar ULTRA is closer to the color of daylight which helps drivers see better at night. A study by the Rensselaer Polytechnic Institute (RPI) found halogen headlights that produce a whiter light can help improve a driver’s reaction time and ability to see roadside objects at night. Price is $49 for a pair with a special rebate of $20 until mid November. For my car, the Sylvania PN is "9003SU".

While doing this, I found that Sylvania also makes a SS version for the coupe's FOG lights, H3ST. So I replaced my 'stock' existing lamps with the new Sylvania H3ST. Same 4000K color temperature and very bright, white light output. Price is $12 - $15 for a pair. Light output for the H3ST is 1315 lumens with maximum wattage of 65 watts."

Replacing Bulb
When replacing the bulb make sure that you do NOT touch the glass envelope with your hands. Since it's in a metal housing, there is no need to contact it albeit by accident. To remove/replace the lamp, remove the cover above the head lamp and move the metal retaining clamp to the top. Then remove the back cover. Next pull of the electrical connector off from the lamp. Then release the two (2) clamping rings that hold the bulb into the headlight assembly. Replace the old lamp with a new bulb and repeat the above steps in reverse.

One point here: It certainly appears that the car's wiring can take the additional current from the 80/100 watts lamps without any difficulty. There was no evidence of burning or excessive heat due to the extra current draw from these hotter burning lamps.

Manual Aiming
Now that I have all kinds of light, I noticed that the low beam from the driver's side headlight is pointed down and angled toward the center. You say what's wrong with that?? It's supposed to be that way but mine was so extreme that the beam hit the ground about 20 ft in front of the car! And it almost intersected the beam from the passenger side. Not very good! If you think about it, the 'mis-aiming' was done intentionally because of the brightness of the previous lamps.

Understanding what is required for manual aiming of headlights will serve as a primer when you aim your Mercedes headlights. This is probably one of the overlooked details after a lamp is replaced. Note that YOU DO NOT HAVE TO AIM the headlight if it was ok prior to replacing the lamp. But if it's NEVER been checked or it looks like mine, then you need to aim both headlights.

How to aim your headlights The manual process involves taking measurements and aiming the light against a wall or screen. During this process, park the car on a level floor facing a wall or screen 25 ft away. To guarantee that you can see your headlight's pattern means that you should do this at night! First, measure the vertical distance to the geometric center of the headlights. This is the hard part -- what is the geometric center? On some lights, there is a little molded mark to indicate this center. On others, it will be necessary to look into the lens and judge where the center of the bulb is. Transfer this measurement to the wall. Measure the distance between the lights. Transfer this and the center line of the vehicle to the wall. Now mark a line 2.1 inches below the horizontal you marked on the wall.

Turn on the lights and aim the low beams to intersect the lower line and the vertical lines where the angle in the beam starts to slope upward as shown in the picture. The obvious problem with this system is all the time it takes. Not to mention the difficulty of accurately making all of those measurements. Also, with some lights, the pattern of light on the wall is hard to judge precisely.

Adjusting S-Class Coupe Headlights
Closeup showing driver's side headlamp Compared to the above procedure, aiming the lights on your coupe is a breeze. But you need to know what to look for, that's why the previous section. You now know that the low beam should fall off 2.1 inches to the top of the beam at a distance of 25 ft from the headlights.

To adjust your Mercedes headlights, do the following (Need to do the same setup as in Manual Aiming section);

Remove the cover above the headlight so you can see the 'bubble' level mounted just below the lamp.

Turn the Vertical Adjustment Screw (VAS) [1] until the bubble in the level [6] is in the CENTER of the heavy middle line (shown in BLUE) and centered between the two outside lines (shown in RED). As you do this the pin indicator [8] next to the screw will move in or out depending on which way you need to turn the screw.

Closeup showing HAS and VAS with 'pin' lengths When the bubble is 'level', then turn the Horizontal Adjustment Screw (HAS) [2] until the 'pin' [7] in the sight glass shows the same length as the other 'pin' [8]. If you are doing this at night (highly recommended), you will see how the light moves up and down with the VAS [1] and left to right with the HAS [2].

The horizontal headlight aim normally never needs to be changed unless there has been a repair to the body or if the headlight assembly has been replaced. If BOTH 'pins' show the same length AND the bubble level is 'plum', then do not make any adjustments.

Adjusting S-Class Coupe Foglights
The unique foglights in the S-Class coupe do not usually need adjustment b/c of the method by which they are mounted. However, if you find that they are misaligned, there is an adjustment 'screw' behind the grill facade as shown in the picture.

Closeup of driver's side foglight adjustment The foglight for the coupe is set to beam so that it fills-in the lower portion of the normal headlight pattern. It's a very wide pattern going from about 120degs off the front beam making it brightly illuminate the side portion of the road. The foglight pattern is also very "narrow" in height as it should be. A properly set foglamp pattern is to be aimed low since that gives the best illumination in dense fog. If the pattern is beamed "UP", then you will be literally blinded in dense fog.

The height of the foglight assy to the center of the internal lamp is about 13" from the ground. To set it properly, make sure that it is no higher than 11" - 12" on the wall 10' away. Adjustment to the beam height is made by turning the screw shown in the picture using a small Phillip's screwdriver. You will find that the adjustment range is very small but enough to ensure that the fog-beam is no higher than the starting dimension to the ground. With the headlights on low-beam, the foglight pattern should pick up where the lower portion of the low-beam pattern fades.

The head- and fog-light adjustment procedure should take you about 10 minutes for each if you have done some 'homework'. The adjustments are very easy to perform and will give you more light where it's supposed to be!
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