Home‎ > ‎

Headlight Upgrade II

Due to flight cancellations from Superstorm Sandy I found myself driving a rented RAV-4 from Pittsburgh PA to Harrisburg PA in height of the storm.  After dropping off the rental at the airport and picking up the Benz, I realized just how bad the lighting in my car was during the drive home.

After doing a -LOT- of reading on various forums a two part upgrade (described below) seemed to be the best solution
By New Years Day all the parts had arrived and it was time to spend a day in the garage and perform the upgradeIt was dark until everything was installed, adjusted and time for a test drive.

During the 20 minute test drive on back roads (no street lights) and highway not one car flashed their lights.  The visibility with these lights is fantastic and well worth the money and time

Part one: Switching to E-Code headlight housings.  The lights for US cars are DOT approved and produce a different light pattern than the ones used in Europe where E-Code (or ECC) regulations apply.  Particularly for this car the DOT lights are very ineffective and produce a poor light pattern.  No one can ever claim they blind oncoming drivers (even with
high wattage bulbs on high).

The E-Codes use a 6 pin connector vs the 4 pin for DOT lights.  A trip to the u-pull-it yard resulted in some 6 pin connectors from a few 124 taillights.  The E-Codes come with city lights, the DOT's don't.  Running a wire from headlight connector to the side marker connector fixed this.  Now when the running (parking) lights are on, so are the city lights
(fitted with LED bulbs).  Details on the 4 pin to 6 pin connector were obtained from here and here.  The DOT lights used a yellow filter over the fog light bulbs.  To keep that yellow light Hella Yellow Star Halogen H3 Bulb's designed for all weather were installed
in the fogs.

The side lights (turn & running) were also changed from North American yellow to European clear (w/yellow bulbs).

Before (DOT Lights):

After (E-Code Lights):

Part two: Install of the H4 HID kit instead of standard H4 Halogen Bulb's.  Many articles have been written about the pros and cons of HID upgrade kits, the requirement for special lenses, are they DOT approved, street legal, etc, etc...  My decision to install HID's was based on the success of several MB forum members who I thank for blazing this trail.

There are almost as many vendors for HID kits as there are people who like French Coffee.  The kit I used was a 35 watt HID Kit from name removed (
I no longer recommend this vendor - details below).  On the advice of their tech support I ordered the optional Error Eliminator Kit to stop the Bulb Out Warning (BOW) light in the dash from coming on.  Sadly this kit did NOT eliminate the BOW,
this is because Error Code Eliminator kits are designed to be plugged between the stock wiring harness and the HID ballast.  Because the W124 uses an H4 bulb connector vs the 9006 on the error code eliminator it can't be connected inline with the stock wiring harness and therefore doesn't work with a W124.  To their credit the vendor issued an RMA and full credit waving the 20% restocking fee

Removing the bulb from the instrument cluster, covering it with tape, or ignoring it were not an acceptable fixes so the search for a solution began.  
After several ideas and some testing I determined that installing a load (resistance) on each circuit (ie: left & right) would make the BOW go out.  My design consists a 12" long cable with a 6-pin male connector on one end and a 6-pin female on the other.  Wired between the low beam pin and ground is a 50-W 6-Ohm Load Resistor.

These load resistors are sold to fool BOW in cars where LED Bulbs have been installed. Because I only installed one resistor on the low beam circuit the BOW does come on with the high beams (I don't use high beams often or for long).  The 6-pin connectors (male & female) came from the local you-pull-it yard and the load resistors from eBay. Total cost for this fix, less than $10 including the solder and heat shrink tubing.  Be aware that these resistors get very hot - so be equally careful where you place these things. 

Update (Dec 2013): 12 months after the upgrade I started having problems with the HID lights.  Initially the left lamp would occasionally not power up.  Then the problem moved to the right and within 1 week the right lamp would not power on at all.
Not having hours to wait on hold I opened a support ticket on the DDM website that resulted in pure frustration.  They offered no tech support to help and diagnose the problem and simply suggested I return the parts and they would test everything for a fee.  Sure and in the meantime what do I use for lights?  I refused and they closed my ticket.  Each time I opened a ticket to continue / expedite the issue more useless advice was given and each ticket closed.  Through part swapping I was able to determine that the right ballast was bad.  Returned it to DDM via 2 day shipping for exchange under their lifetime warranty.  A week after receipt I received an email and acknowledgement the ballast was defective and a new one was being shipped.  My note indicating that I wanted to buy a spare ballast was ignored!  Silly me I expected the replacement part to be shipped from the vendors US address - same as the original kit.  That was a mistake, it was shipped via China Post on that famous "slow ship".  Eventually the part did arrive and I have 2 working lights again.  However the customer experience was something that belongs in a Dilbert cartoon.  For this reason I can no longer recommend DDM Tuning or their HID kits.

Update II (Oct 2014): The BOW came on recently when turning on the headlights.  That's very odd because the resistors have been successfully fooling the BOW module since Jan 2013.  Turns out that one of the resistors had given up the ghost.  Although the resistors worked, they get very hot and were always a concern for me.  Based on this post from Scott McPhee along with the ULN2455a product spec Scott posted I was inspired to reverse engineer my N7 module.  In the end removing 4 diodes (2 for the lows and 2 for the highs) stopped the BOW indicator from coming on while using the headlights.  The other plus to this fix is that those big 'hot' resistors are gone!  If you want details on this mod read my post here.

Update III (Oct 2014): For several months the left headlight (original ballast) would on occasion not activate.  When it did power on it seemed to be dimmer than the left headlight.  Checking the wiring harness revealed that 12 volts was being feed to the ballast indicating a issue with the unit.  Flipping the lights on and off several times would sometimes cause the ballast to fire up.  Due to this uncertainty I ordered and installed a replacement ballast (not from the original vendor!).  I'm happy to report my problems have been solved and I have a (somewhat suspect) spare ballast in the boot with my other 'emergency parts'.

Time for the finished product photos and a video!

City Lights & Daytime Running Lights

Low Beams & Daytime Running Lights

Low Beams, Fog Lights & Daytime Running Lights

Fog Lights & Daytime Running Lights

City Lights & Daytime Running Lights

video shows the completed install: city lights, fogs, low and high beams.  The bulbs are not as blue as they appear in the video, the color was due to where the camera was sitting and the fact that I used a Flip camera.

Love that diesel sound

Alignment: The camera was sitting above the left headlight for the following photos.  The right fog light was off during the following photo.  The headlights (car) were 20 feet from the door, the red dot was projected with an LED level and indicates the center of the car about 4 inches above the bulb height.  Each photo is liked to the full size original.

Low Beam:

High Beam:

Fog Light: