Bad Rear Fog Lamp

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JimG

Member
Joined
Nov 24, 2019
Messages
5
My right rear fog lamp is out in my 2016 B250e, so I removed the lift-gate light module to find that is doesn't appear to come apart any further. does this whole module need to be replaced if any of the lights inside are bad?
 
JimG said:
My right rear fog lamp is out in my 2016 B250e, so I removed the lift-gate light module to find that is doesn't appear to come apart any further. does this whole module need to be replaced if any of the lights inside are bad?
JimG,

The USA spec B250e has the European single high-intensity rear fog lamp on the driver's side. Activated by the separate button adjacent to the light switch. No fog lamp on the passenger side. This is to warn the traffic behind while driving in thick fog (back home in the UK) I'm a little surprised the USA version has it.

I haven't dismantled the light cluster so I'm not sure if the LED bulbs are accessible.

Peter,
 
Thanks. That would make sense as to the lack of a light on the passenger side. When I had the module removed, it wouldn't come apart any further, that I could see. A single LED on only the drivers side seems like an odd feature, even for a European spec.
 
Jim G,

It seems odd that the fog light would only be on one side, not both, so I looked at my rear light assemblies. Both seemed to have three bulbs. Checking the schematic on the internet, it can house 3 bulbs and one of them is marked as a fog lamp. See the link https://www.oembenzparts.com/oem-pa...xJmw9MyZuPVJlY29tbWVuZGVkIFByb2R1Y3RzJms9MQ==.

So I am a little confused. Peter, can you shed further light on this?
 
JeffRay said:
So I am a little confused. Peter, can you shed further light on this?

Jim and Jeff, and all,

I'm certainly not an expert on region-specific rules, but this article will shed some light on the topic (pun intended...)

The high intensity fog lamps were introduced in the early 1980's to vehicles in the UK. These reduce the terrible multi-vehicle pile ups on motorways blanketed by fog. As an expedient on existing production vehicles one of the two white reversing lamps was changed to red, and operated by the driver when driving into a fog bank. The other white reversing lamp was retained and operated by selecting reverse gear.

According to United Nations (UN) Regulation 48, vehicles must be equipped with one or two bright red "rear fog lamps". On newer vehicles there may be one or two rear fog lamps. If only one is fitted for RHD vehicles (UK, Japan, Australia) this would be on the other side of the vehicle to most of CDN, EU, and USA, where LHD is the norm.

This type of fog lamp is not required in the USA, but is allowed on imported vehicles. That appears to include the B250e. I suspect that the rear lamp housings can accommodate lamps on either side, or indeed both. In the USA B250e I don't know if both are fitted, but would not be surprised if only one is active.

For further study about vehicle lighting head over here on Wikipedia.

Peter,
 
JimG,

In looking at the schematic, one can just replace the bulbs vs. having to replace the entire thing. This is consistent with my experience with MB light fixtures as I recently had my mechanic replace the main bulb on the 2006 MB wagon and I had a similar concern. Just a bulb replacement that cost me $40, mostly labor as it was bloody difficult to get to it in the engine compartment.

The rear hatch on our B250s is easier to get to. Figuring out how to remove the back of the entire thing is the tricky part. If you have a problem doing so, let me know and I will ask my mechanic. I need to drop my B250e off this winter so he can replace the front end damaged when someone backed into it when it was parked on the street. BTW, the insurance check was for over $5K to cover a new front bumper, left quarter panel, new left front bulb and of course labor. I can ask him to show me then.

Good luck.
 
JeffRay said:
I looked at my rear light assemblies. Both seemed to have three bulbs. Checking the schematic on the internet, it can house 3 bulbs and one of them is marked as a fog lamp. See the link https://www.oembenzparts.com/oem-pa...xJmw9MyZuPVJlY29tbWVuZGVkIFByb2R1Y3RzJms9MQ==.
Jeff,

Thanks for researching the B250e Lamps. I'm skeptical as my B250e has all LED lamps at the rear. LED lamps are very reliable, and consume less power than "Edison" hot filament lamps, and will one day replace them (Edison has a good run...!)

I looked at my B250e. The button next to the light switch turns on an amber indicator in the RH gauge, and a bright red LED cluster only on the driver's side rear.



To Be Continued (This Forum only allows two PIX attachments)

Peter,
 
Part Two

Here's the Rear Fog Lamp LEDs. Driver's side only, the Passenger side never lights up.


Continuing my investigation I noticed the Rear Fog Lamp is turned off when the vehicle is turned OFF, as expected.
There are other positions on the Light Switch, including two parking lamp settings for either Driver or Passenger side.
These activate the white "Eyebrows" at the front, and do not require the vehicle to be turned ON. Interestingly they do not have any rear lights.


If the Light Switch is in either Marker or Headlight positions there is a warning message when the vehicle is turned OFF.
I leave it on the AUTO position, because Citizens here in California are not allowed to think for themselves...!

To Be Continued (This Forum only allows two PIX attachments)

Peter,
 
Part Three

The B250e's Parking Lamps brought back a happy childhood memory. When I was very young my Grandparents would visit in their new 1963 Ford Anglia, my parents didn't drive as was typical of post-WWII Londoners. I had limited access to motor cars.

My Grandfather would attach a portable Parking Lamp when he parked overnight on our residential street. This fit outside n the driver's side window, and connected directly to the car battery with a cable and clips. He always worried that it would deplete the battery over night, it never did, but he turned it off at day break. There was a relatively small bulb with a Red and a White window facing front and back. If he parked on the opposite side of the street the Parking Lamp went on the passenger window. He got a driving license in the early 1930's.

Google found a PIX of a similar type used in the UK.


My B250e Rear Fog Lamp (couldn't fit this PIX in to Part One above)


Peter,
 
Ah, the mystery of your web named revealed. Great story.

You know, I have had a B250e since 2014 and never took the time to figure out the light positions other than Auto and On. Good thing someone is paying attention.
 
JeffRay said:
Ah, the mystery of your web named revealed. Great story.
Jeff,

We all have childhood memories, hopefully fun and nice to revisit a half century later. I forgot to explain that the Parking Lamp was a lawful requirement. Your friendly foot patrol Copper would have a word or two if you forgot to put it up each night.



Ford of England had several Ford Anglia versions over the years, this is what I recall my Grandparents owning. BTW, there's a nicely restored RHD Ford Anglia 105E trundling around Palo Alto, California. It's the Deluxe model. Seems very quaint and tiny to me as an adult.

JeffRay said:
You know, I have had a B250e since 2014 and never took the time to figure out the light positions other than Auto and On. Good thing someone is paying attention.
Not to worry, I'll do the investigating. From what I read in the official Owner's Manual for the B250e the authors may never have seen or driven the vehicle. There's some vague hand-waving on details we discuss in depth here.

Back to the rear lights. I wonder if the 2014 vehicle still had "Edison" style bulbs? The switch to LEDs may have come later. the Owner's Manual has remarks about LED and Bi-Xenon (headlamps) which may have been an option. I think I may have one or two non-LED types (license plate, door open markers) on the MY 2017.

Peter,
 
Small correction to my earlier comment about European-style parking lights. I tested my B250e after dark last night, and there's a parking lamp front and rear. The Light Switch let's you choice the driver or the passenger side. At night these are surprisingly bright! I wonder if I use the parking lights locally I will get reminders from neighbors that I accidentally left my lights on?





Peter,
 
Peter,

Thanks for your very thorough confirmation. My setup is exactly like yours. When I had pulled the light module to check it out initially, I could see that the lights were led's, but there was no way to get inside the module. I just find it odd that a safety feature would only be on one side, especially for the US market.

JimG
 
JimG said:
I just find it odd that a safety feature would only be on one side, especially for the US market.
JimG,

The Rear Fog Light is not a USA requirement, but it is in EU. The USA does not ban import vehicles, such as the B250e, from having this feature.
Historically there were terrible motorway pile ups in the UK due to low lying fog banks. It was determined that a high intensity rear light helps traffic avoid rear-end collisions.

It is only on the driver's side to help guide following traffic to avoid overtaking on the wrong side of practically invisible slow traffic. If the traffic pulls off the road or stops on the shoulder it's important that following traffic doesn't try to pass on the passenger side, which is technically illegal in the UK, and accidentally drive into a ditch or barrier. For export models the light fitting has to be available on both sides of the vehicle, but only active on the driver's side.

I remember well the London Fog (and not the American raincoat brand) You could not see your own hand in front of your face. Walking to high school often required following the road curb.

There's vehicle localization that doesn't apply across the board. EU has some country-specific rules. I was pulled over by the Carabinieri in Rome for using the Italian-specific DRL (Daytime Running Lights) headlight on the wrong class of roadway. Luckily, just a finger-wagging... Suddenly I had forgotten any Italian language, not that I'm very proficient! Molte bene!

Peter,
 
Peter,

Even though I live in NYC, I can tell you that at least once a year, someone alerts me that I have left my parking lights on in one of my cars. It has been our doorman, the garage guys across the street, my neighbor and the local pub bartender. Someone clearly has an observed defect. Sigh. Never drained the battery, thank goodness.
 
JimG,

Looking at the parts schematics and seeing how my mechanic replaced the front turn signal bulb on my admittedly older 2006 E500W, all the bulbs seem to screw out from the back of the housings. I am planning on taking my B250e in later this month to replace the front bumper, left lamp and left front quarterpanel that was damaged by another car overnight while I was parked on the street. Can ask him to show me the rear fog lamp assembly then.
 
I actually took my E350 (my first Benz) into the dealer for this. The service tech kindly informed me that it is for fog, and only on one side as to not to confuse it with a stuck brake light on situation.
 
So I had some extra time plus it had stopped raining so I found the fog lamp switch and pressed it (first time in 5 years, not a lot of fog here). Went around the back and indeed, only the left side bulb was lit and on the right side, no bulb. Did not have time to look at housing but it appeared from the outside as another rear install bulb. Oh yes, mine is a 2017.
 
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