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Thread: Rear fog lights.

  1. #1

    Default Rear fog lights.

    In reading a thread or two here in the automotive lighting section, I keep seeing reference to rear fog lights. I am intrigued with the idea. So as I understand it, in Europe, they are required or at least much much more popular than here in the US. I already mentioned in anther thread I have become a fan of DRL's, and now a rear facing "safety" light makes just as much sense. I have picked up bits of info, such as if you run one it needs to be on the driver's side, they cannot be closer than 4" to the regular tail/brake lights, and it must be a switched light.
    So, where I live we have inversions (fog for up to a couple of weeks!) not to mention plain ol' fashioned fog by itself. Being a retired deputy, I would have to search Idaho code pretty close, but at this point, I THINK they are legal. I will have to further that inquiry.
    If they are deemed legal, what would be my options? Are they supposed to be as bright as a brake light? Could a guy simply wire in a aftermarket "brake light" such as what is sold at local auto parts store?
    Or, am I wasting efforts here?

  2. #2
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    Default Re: Rear fog lights.

    Required in Europe. Light output similar to a brake light, but somewhat different photometric requirements. Heck, once upon a time, Cibie made a series 45 red rear fog that used a 55w H2 bulb. In my recent thread on Wiring Rear Fog Lights, Virgil gave good advice on how to hook them up. Separate switch and a good indicator light. You do not want to leave them on when they are not needed.

    There's debate over having one vs a pair. Newer cars tend to integrate them into tail light pods and install pairs. I also understand that some cars have used the equivalent position on the driver's side for the rear fog and the right side for a backup if in Europe, but sold the car in America with two backup lights.


    I kind of like the old fashioned way, tail lights above the rear bumper but a rear fog hanging below the bumper in a position between the center and the driver's side. It not only looks "odd" and gets attention, but I think the lower mounting may sometimes help it shine beneath the fog. But others will say a pair gives a better idea of distance and closing speed. There's no doubt the rear fog is visible farther away than ordinary tail lights. We really should use them (properly!) here.
    There are two kinds of light - the glow that illumines, and the glare that obscures. ~James Thurber

  3. #3

    Default Re: Rear fog lights.

    Quote Originally Posted by Bill, Idaho View Post
    In reading a thread or two here in the automotive lighting section, I keep seeing reference to rear fog lights. I am intrigued with the idea.
    More detailed info on rear fog lamps can be read here, and you will want to take a look at this thread (the whole thread, both pages) for answers to which/what/how types of questions. No, you cannot just slap a brake light or other light that happens to be red on and call it a rear fog lamp! You need an actual rear fog lamp. They are not the same as brake lights or any other kind of lamp, and (like all car lights) they have their own technical standards to meet.

    So as I understand it, in Europe, they are required
    Yes, they are, on all vehicles since about 1979.

    I have picked up bits of info, such as if you run one it needs to be on the driver's side
    Actually, if you run one it needs to be somewhere between the vehicle's longitudinal centerline and the driver-side extent of the rear of the vehicle.

    they cannot be closer than 4" to the regular tail/brake lights
    There is no requirement for rear fog lamp spacing to the tail light. The European/international regulation specifies no less than 4" distance between closest lit edges of the rear fog and the brake light. This rule doesn't apply in North America (where the international regs aren't recognized) but still very smart to follow it, and apply it with regard to the turn signal, too.

    and it must be a switched light
    And there must be a telltale (indicator) clearly visible to the driver in the normal driving position. Again, the international rule states that the rear fog(s) can be activated only if the headlamps and/or front fog lamps are lit, and has to be switchable (can turn it off) independently of any other lamp. The latest version of the rule further specifies that once switched on, the rear fog(s) may remain on until the vehicle's parking/tail lamps are switched off (practically, this means the headlamp switch is turned all the way off), and then the rear fog(s) must remain off until deliberately switched on again or, as an alternative to that, an audible warning (like a buzzer, beeper, chime, etc) must sound if the ignition is switched off or the ignition key is removed and the driver's door is opened while the rear fog switch is on the "on" position. These last two provisions are intended to safeguard against misuse of rear fog lamps -- they are glaring and distracting if they're misused by being switched on when they shouldn't be.

    Other requirements include mounting height (at least 10" and no more than 39" above the road surface) and unobstructed visibility (5° upward to 5° downward, 25° to the right and 25° to the left of the lamp's axis, and the lamp's axis has to be pointing straight to the rear).

    Rear fog lamps are not specifically, directly, or indirectly prohibited or regulated in Idaho; if you follow these mounting and hookup rules, you will have an optimally safe setup. It is a little complex but not impossible to put together a switching circuit that meets the anti-misuse provisions -- a good idea because even the most careful of us forget to turn off a switch from time to time (and Idaho does require that vehicle signal lights not be glaring).
    Last edited by -Virgil-; 02-09-2017 at 11:05 PM.

  4. #4

    Default Re: Rear fog lights.

    Interesting requirements. Our '92 190E has it on driver side only. Activating it by pulling out the headlight knob two notches makes an indicator in the center glow. It only allows pulling when turned to parking lights, or headlights mode. Pulling one notch activates the front fog lights, so they have to be on as well. As far as I know the smart fortwo 451 model does not come with one for the rear here in the US, but it does in other countries. Strange thing is that the switch in the center console for this is not lit/no indicator, unless I am mistaken....

  5. #5

    Default Re: Rear fog lights.

    The indicator is on the dashboard.

  6. #6
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    Default Re: Rear fog lights.

    Quote Originally Posted by -Virgil- View Post
    ...
    Yes, they are, on all vehicles since about 1979.
    ....
    Hi,

    Do you have an official reference for that please ?

    Cheers.
    Last edited by coffeecup66; 02-13-2017 at 11:25 AM.

  7. #7

    Default Re: Rear fog lights.

    Quote Originally Posted by -Virgil- View Post
    The indicator is on the dashboard.
    It's obvious I haven't successfully retrofitted mine yet huh? 😂

  8. #8
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    Default Re: Rear fog lights.

    Quote Originally Posted by jzchen View Post
    It's obvious I haven't successfully retrofitted mine yet huh? 
    Nice pics here:
    http://www.fq101.co.uk/how-to-guides...55-speedo-leds

  9. #9

    Default Re: Rear fog lights.

    Quote Originally Posted by coffeecup66 View Post
    Thanks for the fq101.co.uk link. I think that is for modifying the instrument cluster LEDs. I have sent a request for where to find the proper wiring diagrams for the lights. (I'm afraid smarttekinfo.com has limited wiring diagrams for non-USA designs.)

  10. #10
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    Default Re: Rear fog lights.

    Quote Originally Posted by jzchen View Post
    Thanks for the fq101.co.uk link. I think that is for modifying the instrument cluster LEDs. I have sent a request for where to find the proper wiring diagrams for the lights. (I'm afraid smarttekinfo.com has limited wiring diagrams for non-USA designs.)
    How'bout zz'is here:
    - http://www.evilution.co.uk/123

    (coming from http://www.smartcarofamerica.com/for...-switch-49312/)

  11. #11

    Default Re: Rear fog lights.

    Quote Originally Posted by coffeecup66 View Post
    ...
    Yes, they are, on all vehicles since about 1979
    Do you have an official reference for that please ?
    What counts as "official" for your purposes...and what are your purposes? I got it out of this book.

  12. #12
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    Default Re: Rear fog lights.

    Quote Originally Posted by -Virgil- View Post
    What counts as "official" for your purposes...and what are your purposes? I got it out of this book.

    Hi,

    What are my purposes ? Simply, accurate correct and reliable information (as opposed to opinion or hearsay), for good knowledge.
    Curious question... Suggests you could have a problem sharing your sources of information.


    Official ? You are talking about a legislation that requires all european vehicles to be equipped with rear fog lights. Only european directives or a regulations can do that. Do you have a link to one of those please ?

    This is an example of an official source :
    - https://www.senat.fr/questions/base/...941209180.html


    Btw, your link to the Hella book seems "half-dead". I'm talking about that link, not your source.


    Cheers.

  13. #13

    Default Re: Rear fog lights.

    Quote Originally Posted by coffeecup66 View Post
    What are my purposes ? Simply, accurate correct and reliable information (as opposed to opinion or hearsay), for good knowledge. Curious question... Suggests you could have a problem sharing your sources of information.
    No, I was trying to figure out whether you needed a government-sourced document, for example because you're having problems getting a vehicle registered or imported due to a dispute about required equipment, or had some other kind of need. You can maybe take a look at my posting history and see for yourself how much of a (nonexistent) "problem sharing my sources of information" I have.

    Only european directives or a regulations can do that. Do you have a link to one of those please ?
    Not hard to find on this board. Those are linked here. They contain information on what is required, not information on when the requirement was introduced, so they will not answer your question.

    This is an example of an official source: https://www.senat.fr/questions/base/...941209180.html
    This source says European regulations (that would be ECE Regulation 48) require rear fog lamps as from October 1, 1990. That's possible; there was a strong push for pan-European uniformity in the 1989-1994 period -- it's when France's requirement for selective yellow headlamps, the UK requirement for dim-dip lights, the Swedish requirement for headlamp wipers, and other national oddities were supplanted or overruled by treatment of those subjects in the European regulations.

    The German-to-English translation in the book I linked is somewhat crude in places; the original German text may have meant that some countries started requiring rear fog lamps in 1979. I note that this official source says that rear fog lamps are required in the UK on vehicles first used on or after April 1, 1980, and this paper (by noted vehicle lighting researchers at the renowned University of Michigan Transportation Research Institute) states the applicable ECE Regulation (R38) came in 1978.

    Btw, your link to the Hella book seems "half-dead".
    It's 100% live when I click it. Anyone else want to try clicking it and report what happens?
    Last edited by -Virgil-; 02-13-2017 at 04:45 PM.

  14. #14
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    Default Re: Rear fog lights.

    Quote Originally Posted by -Virgil- View Post

    It's 100% live when I click it. Anyone else want to try clicking it and report what happens?
    Works fine for me.
    My Lights: SureFIre 6px Pro, SureFire Maximus Headlamp
    2007 Dodge Power Wagon
    : JW Speaker TS4000 Driving Lights, Grote 30" OffRoad LightBar
    - Bosch Compact 100 Fog-lights, Grote BriteZone LED Work Lights

  15. #15

    Default Re: Rear fog lights.

    GTG for me, too.

  16. #16
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    Default Re: Rear fog lights.

    "100 Years of Hella: From a Lamp Workshop to Global Supplier to the Automobile Industry, 1899-1999 Hardcover – 1999"
    It's life, Jim, exactly as we know it.

  17. #17
    Moderator Alaric Darconville's Avatar
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    Default Re: Rear fog lights.

    Quote Originally Posted by -Virgil- View Post
    I note that this official source says that rear fog lamps are required in the UK on vehicles first used on or after April 1, 1980, and this paper (by noted vehicle lighting researchers at the renowned University of Michigan Transportation Research Institute) states the applicable ECE Regulation (R38) came in 1978.
    That 1978 date for the filing of ECE R38 is also found in here (scroll down to page 174). (Did Minitrue ALSO edit THAT source?)

  18. #18

    Default Re: Rear fog lights.

    That's a good find, Alaric. It helps resolve these late '70s/early '90s date questions; the answer is "both": "The national German law required the installation of rear fog lamps for new motor vehicles since January 1st 1991. Much earlier (1976), the relevant legislation of the European Community required rear fog lamps on passenger cars. But until 1997 (for new vehicle types) the vehicle manufacturer had the free choice to have the vehicle homologated according to the individual national specifications (multiplied by the number of EU-Member states) or once acc. to the common directive - as far as the installation of lighting equipment is concerned. Since 1998 the new vehicle certification is restricted only to the EU-Directive WTA (Whole Vehicle Type Approval, i.e. 70/156). The respective ECE-Regulation with the technical specification for the lamp was filed in 1978 as Reg. No. 38."

  19. #19
    Moderator Alaric Darconville's Avatar
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    Default Re: Rear fog lights.

    Quote Originally Posted by Bill, Idaho View Post
    So, where I live we have inversions (fog for up to a couple of weeks!) not to mention plain ol' fashioned fog by itself.
    Quote Originally Posted by -Virgil- View Post
    Rear fog lamps are not specifically, directly, or indirectly prohibited or regulated in Idaho; if you follow these mounting and hookup rules, you will have an optimally safe setup.
    It definitely sounds like you have a need for a rear fog lamp, and since there is no real legal obstacle to installing and using one (or them, if you choose to run a pair), rather it's just finding the time and materials and making the effort, you should go for it. Think of it as a Heathkit project, except you'll be crawling around your car and running wires and... It'll be fun!

    Quote Originally Posted by -Virgil- View Post
    That's a good find, Alaric.
    I'm working to become a 5th Duan Wei in Google Foo (I've been at the 4th rank for far too long).

  20. #20

    Default Rear fog lights.

    I do not know when rear fog lamps were first used but I do know that the first Mercedes model I saw that had them integrated into the factory installed rear light units was the Mercedes R107 (2 seat SL) that was introduced in early 1971. I was in Germany in 1971 taking part in war games during my brief Army stint and saw vehicles using rear fog lights during foggy mornings. Both the 1973 450SEL and 1979 240D I bought in the 1970's had spaces for rear fog lamps in the rear lamp units but sockets for them were not provided in U.S. specification cars even though the dashboard light switches supported rear fog lamps. I considered installing sockets for rear fog lamps in the 450SEL but I abandoned the idea due to the light socket panel having printed circuits instead of wires and there was no printed circuit on the socket panel for rear fog lamps. The 1979 240D had traditional wires leading to the rear lamp sockets so it was relatively easy for me to install the missing sockets and to run wires from it to the existing lamp switch on the dashboard.

    I've installed a rear fog lamp (never more than one) on the rear of other vehicles over the years. Maybe my "favorite" was the 21W Hella rear fog lamp that I installed on a 1985 Honda CRX Si that I used mainly to drive from Kansas City to Colorado ski slopes in Winter. IIRC, the CRX Si was the first fuel injected Honda car sold in the U.S. and I had one of the first - it drove like a rally car and was wonderful on snow. But it was tiny and I felt very vulnerable - particularly since my Winter ski trips sometimes involved driving in full blown blizzards with near zero visibility ... such as the time I was stuck in Western Kansas for several days when the snow drifts were all the way up to the overpasses on I-70.

    I'm getting old and reminiscing.
    Last edited by -Virgil-; 02-17-2017 at 07:49 PM. Reason: Remove off-topic material

  21. #21
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    Default Re: Rear fog lights.

    Bill, Idaho

    Shouldn’t fog lights be very visible? I mean, if fog lights are at least not as bright as an ordinary rear bumper lights, will it still be safe? someone mentioned about having a red fog light instead. I think, in my opinion, red light would be a better choice. It is not blinding as the white one, and it means stop once the car from behind sees it. Anyway, its just a thought.

    Thanks,
    Pryarch

  22. #22

    Default Re: Rear fog lights.

    They *are* typically red and about the same brightness as a brake light. The photometric requirements are slightly different however. It is apparently possible to make a light that fulfills the requirements of both, however; off the top of my head, the E92 BMW 3-series uses the red segments in the trunk as auxiliary brake lights (light up only under heavy braking) as well as rear fogs. Also the 2nd series Scirocco moved light positions around between ROW and USA although off the top of my head I don't remember exactly which segment did what, sadly that car left over a decade ago and the specifics escape me. I do remember feeling cool whenever I'd spot another Scirocco with the lights arranged in the Euro/ROW pattern
    Last edited by -Virgil-; 02-19-2017 at 01:27 PM.

  23. #23

    Default Re: Rear fog lights.

    Pryarch, welcome to the board.

    The lamps we're talking about in this thread are rear fog lamps. They're always and only ever red, they're much brighter than taillights, and they're completely different from front fog lamps. Please click the links (underlined text) in post #3 of this thread to learn more about them. Also, while some car lights are mounted in the bumper, there is no such function as "bumper light".
    Last edited by -Virgil-; 02-19-2017 at 01:28 PM.

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