Rear fog lights

Discussion in 'Electronics' started by Marku, Jun 20, 2017.

  1. Marku

    Marku Active Member

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    Is it the same on all Mercedes? Our Viano only illuminates the driver's side rear fog light. The bulb is in place on the left but doesn't light up. The bulb is OK so is it standard for only the offside to light up and can you select the near side if wanted, for example driving in France or even better can you have both together, or do you have to have it done by MB dealer? The nearside has never worked and there has never been any error message which I think there would be if there was a fault.
     
  2. renault12ts

    renault12ts MB Club Veteran

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    It's the same on nearly all brands of car.
     
  3. KillerHERTZ

    KillerHERTZ Administrator Staff Member

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    It's to stop it looking like you are braking.
     
  4. GP801

    GP801 MB Enthusiast

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    Most markets only have the offside however I noticed in France that most cars have 2 rear fog lights illuminated. The bulb holders tend to be the same but the loom only has the connections according to local custom. For the 124 I rigged up a feed from one side to the other so that I can just swap the bulb over when on the continent. I suspect on more modern cars this would upset the system and fail miserably.
     
  5. Dec

    Dec MB Enthusiast

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    Some have two as in attachment below.

    Dec

    [​IMG]
     
  6. whitenemesis

    whitenemesis MB Club Veteran

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    On more modern MBs wouldn't they substitute a failed brake lamp with the fog lamp?
     
  7. Chrishazle

    Chrishazle MB Enthusiast

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    I have a flea in the back of my memory that at some time in the not too distant past, probably an EU ruling, twin rear foglights like on my 968 were outlawed and only the offside (for the country the car was made for) was allowed.
     
  8. Ted

    Ted MB Enthusiast

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    I thought the same, but a recent trip up the M40 in heavy fog saw quite a few recent reg cars with two rear foglights.
    The very small high brightness ones á la golf/passat were excellent and didn't mask the brake lights.
     
  9. OP
    OP
    Marku

    Marku Active Member

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    All the vehicles we have had previously had two and on the Viano the fog lights are separated vertically from the brake and tail lights by about 600mm. Any way if it is to denote the driver's side its obvious that you would not be able to take the vehicle to any other country in Europe. The manual says nothing about being able to select the other side just referring to the "driver's side". In poor visibilty I would think defining the width of a vehicle was a necessity.
     
  10. BTB 500

    BTB 500 MB Club Veteran

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    AFAIK in the UK it's still legal to have one (on the offside) or two.
     
  11. BTB 500

    BTB 500 MB Club Veteran

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    There's a legal minimum distance required between brake and fog lights. Also a maximum height above the road, IIRC.
     
  12. whitenemesis

    whitenemesis MB Club Veteran

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  13. triple h

    triple h Active Member

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    Attached Files:

  14. whitenemesis

    whitenemesis MB Club Veteran

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    No lamp monitoring on your '99 BMW?
     
  15. Codger49

    Codger49 MB Enthusiast

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    This dual rear fog lamps mod has been described a few times in e46 forums.

    I believe that reversing light bulbs are not monitored on a E46, so maybe the rear fogs which are in the same boot lid mounted unit aren't either. Certainly pre-facelift E46s have lamp monitoring for those lamps in the body mounted light unit.
     
  16. triple h

    triple h Active Member

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    there's a car symbol on the speedo that tells me if a door is open or a bulb has blown like in this pic
     

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  17. triple h

    triple h Active Member

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    i had changed one of the reverse light bulbs for one that had an alarm/buzzer, a bulb warning appeared on the car symbol but went out when i put the original bulb back in again
     
  18. Codger49

    Codger49 MB Enthusiast

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    Found a training document for E46 Driver Information:

    Lamp monitoring on the E46 is a function of the LSZ control module. The following lamps are monitored in both the hot and cold states:
    • High/low beams
    • Brake lights - left/right
    • Turn signal lights
    • Tail lights
    • Parking lights
    • Side marker lights
    • License plate lights

    Hot monitoring takes place when the lights are switched by monitoring the current flow through the lamp filaments.

    Cold monitoring takes place by the LSZ when the lights are switched off. The LSZ will briefly activate the lighting circuits and check for current flow through the lamps. The lights are not switched on long enough to illuminate the bulbs.

    (Table of Contents E46 DRIVER INFORMATION - bmw)
     
    2 people like this.
  19. OP
    OP
    Marku

    Marku Active Member

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    But none of this tells me why I can't have both rear fog lights. Both units are the same and the wiring. LHD vehicles must have the left rear fog light illuminated so there must be a way to switch between them. I can't think that the vehicle has to go in to the dealer for this. The manual makes no mention.
     
  20. Dec

    Dec MB Enthusiast

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    Is the non working left hand side bulb exactly the same as the right side working bulb?
    If the right side fog bulb were to be removed, could that cause the left side bulb to work?

    Dec
     
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