Automotive Would this make a good rear fog light?

-Virgil-

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No, that would not make an OK, acceptable, legal or safe rear fog lamp. The mounting is convenient, but given the allowable range of license plate angles it's almost totally random where this light would be directed. Remember, just because it's red and faces the rear, doesn't make it a rear fog lamp (or a brake lamp, etc). Just because it's white doesn't make it a reversing lamp if we put it on the back of the car or a daytime running light on the front. Just because it's amber doesn't make it a turn signal if we put it on one side of the front or rear of the car and blink it on and off. There are detailed requirements (not guidelines/suggestions) for each and every category of lighting device/function for roadgoing vehicles, way more detailed than just "red and faces rear and puts out 143 cd somewhere in the beam".

Sorry...!
 

toledoUPSguy

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no apology needed, thank you for the reply. I have been studying this subject but darn computer completely crashed and I've lost all the stuff I saved. I know you are familiar with the specs, is there really much difference between a rear brake light and rear fog? Also doesn't the SAE spec say it should say F2 on the lens, pretty sure there isn't one of those anywhere. Please don't misunderstand what I'm asking here as I'm not trying to be a cheapskate. I have no problem spending money on quality products, have almost a grand in 2 sets of Diode Dynamics SS3 pods, SAE max fog in selective yellow and Max driving. Also big dollars in OWL weapon lights, But if we look at this from Hella that doesn't even seem available here in the states....
https://catalog.hella.com/catalog/product/view/id/109417/s/2NE 980 889-501/

or this from Peterson...
https://petersonlightsandharnesses.com/product/led-back-up-lamp-assembly-47/

what is the real difference between these and the very similar looking "junk" sold on ebay or amazon as "fog" lights?
 
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-Virgil-

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is there really much difference between a rear brake light and rear fog?
Yes. The minimum axial intensity (at a single test point straight out from the stop ("brake") lamp is 80 candela per SAE J586. The minimum intensity for a rear fog lamp, per SAE J1319, is 125 candela along the horizontal line from 10 degrees Left to 10 degrees Right, and along the vertical line from 5 degrees Up to 5 degrees Down (these lines cross at the axial point mentioned above). The intensity must not be less than 62.5 candela everywhere in the region ("zone") defined by the diamond shape formed by the endpoints of these lines. That's the upper diagram in this attached picture. The lower diagram is the stop light specification, and as you can see it's a lot more complex. The circled numbers are the minimum candela values at specific test points, and the pink shaded zones have their own requirements, too -- it's not enough to just meet the test points; the zones also have to be fulfilled. For both the rear fog lamp and the stop lamp, the maximum intensity everywhere in the light distribution is 300 candela. Note that these two specifications are not mutually exclusive/incompatible; it is possible to make a single lamp that meets both the stop and rear fog functions. But meeting one of the specs doesn't guarantee meeting the other one.
FogTail Versus Stop.jpg
Also doesn't the SAE spec say it should say F2 on the lens
Function markings like "F2" for a rear fog lamp or "S" for a stop lamp are not legally required, and they actually aren't even required by the SAE standards themselves. J586, for example, says stop lamps "may" be identified by the code 'S'.
But if we look at this from Hella that doesn't even seem available here in the states
That's a fine one. Everything from Hella is available here, you just need to know where to look! You can either go it alone (put the Hella part number in a search on Google, Amazon, or Ebay), or check with Daniel Stern or another reputable vendor.
or this from Peterson
That's another good choice, and probably faster/easier to buy here. There are numerous brackets available to mount these lamps, such as these, these and these. There are round versions of these lamps/brackets, too.

If you go to install a rear fog lamp, or a pair of them, keep in mind the hookup and switching arrangements need to be appropriate, not just a simple on-off switch. Rear fog lamps can cause serious glare and other safety problems (stop lamp masking) if they're indiscriminately used or forgotten and left on. Factory installations have to be set up so the rear fogs can be switched on only if the front fogs or headlamps are on, and if the headlamps/front fogs and/or the ignition is switched off, the rear fogs also have to go off and stay off until manually activated by the driver. There's a nice little kit available to make it easy.

what is the real difference between these and the very similar looking "junk" sold on ebay or amazon as "fog" lights?

The reputable-brand items are engineered, designed, manufactured, tested, and certified (and/or approved) as legitimate safety devices. Off-brand (or no-brand) items...aren't. Again, it's not just a red light, there's much more to it than that.
 

Qship1996

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I can highly recommend the Peterson 850 fog lamp as a durable, well made product as it is almost exactly 6 years ago I started this thread and had one installed on my Highlander and as of today remains operating and looking like new, and that is on a vehicle that is parked on the oceanfront subject to salt mist year round and nasty brine juice sprayed on the roads in winter when the officials "feel" there may be ice/snow conditions, which thankfully usually eludes us here at the Delaware beaches.
 

toledoUPSguy

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Virgil, the 2 diagrams you posted, is there a measurement distance associated with cd requirements or is it right at the light? Thank you again for posting that.

Wow, that is a pricey relay kit there.
 
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LEDphile

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Virgil, the 2 diagrams you posted, is there a measurement distance associated with cd requirements or is it right at the light?
Candela is a measure of luminous intensity, and does not vary with distance in the far field. Not to be confused with the measure of illuminance (lux) that varies with distance due to the inverse-square law. I would assume that the measurements for the standard are taken in the far field, as the transition from the near field (where the source cannot be accurately approximated as a point source) to the far field (where the source can be approximated as a point source) is going to be on the order of a few feet for most automotive lamp assemblies (10x the maximum source dimension is a typical approximation for the near to far field transition).
 

toledoUPSguy

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Candela is a measure of luminous intensity, and does not vary with distance in the far field. Not to be confused with the measure of illuminance (lux) that varies with distance due to the inverse-square law. I would assume that the measurements for the standard are taken in the far field, as the transition from the near field (where the source cannot be accurately approximated as a point source) to the far field (where the source can be approximated as a point source) is going to be on the order of a few feet for most automotive lamp assemblies (10x the maximum source dimension is a typical approximation for the near to far field transition).
I'm going to say thank you for taking the time to respond but I'm going to have to read that a few times to try figuring out what you are saying.
 

-Virgil-

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Virgil, the 2 diagrams you posted, is there a measurement distance associated with cd requirements

Intensity specifications (in candela) are not distance-dependent; you're thinking of illuminance (in lux).

Wow, that is a pricey relay kit there.

$66 and change, plus postage...but you get all the correct components including a switch with the correct symbol that lights up as a telltale, for a "looks factory" type of install. Seems worth it to me.
 

toledoUPSguy

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$66 and change, plus postage...but you get all the correct components including a switch with the correct symbol that lights up as a telltale, for a "looks factory" type of install. Seems worth it to me.

I must have run the calculator wrong since I came up with $166
 

toledoUPSguy

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Decided to quit trying to make something work and will try ordering a real hella rear fog. Is there a thread here somewhere about wiring it up so it has to be reset each time the headlights are off.

Just ordered the hella for $57 on amazon.de, now to figure out how to buy virgil's linked harness for less than the $166 I'm coming up with shipped.
 
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toledoUPSguy

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toledoUPSguy

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Here is my game plan for this, feel free to jump in if something looks wrong. The Hella rear fog is on the way, the cartown.se kit that Virgil linked is here already.

1641587120157.png


I thought this set up hooked up to the battery and then had a trigger or activation that was tied to a light. It doesn't, so what I'm planning on doing is using a Y adapter from Starkey Products that will give me an extra output from my OEM front fog that will be the 12v +and - for the relay and the switch.]
1641591869273.png


a couple of these will make for nice weather proof connections for the harness
1641591990437.png

1641592010029.png



Now the hardest part is going to be figuring out where in the world I can put the switch on the very crowded f150 dash.
 

toledoUPSguy

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By hooking it up this way I "think" unless the front fogs are on there will be no power available to the switch for the rear fog. Also if ignition, front fogs or parking lights go off it will shut the rear fog light off too.
 

toledoUPSguy

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Hella finally showed up today, stinking amazon.de put it in a cardboard envelope for packaging. Twisted and torn. Guess the $45 cartown charged for shipping wasn't bad considering it got here from Sweden in 4 days bubble wrapped in a nice strong box. $11 shipping from Amazon took 17 days and no protection. Going to wait till it gets warmer to start installing this.
 

toledoUPSguy

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This is a lousy picture because it is stinking cold outside. No, it's not mounted there, will go under the bumper. In bright sunlight the tail lights are barely visible but the Hella fog light is shining brightly.
 

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John_Galt

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Any chance you might run it for 20 minutes or so and get a lens temp reading, compared to ambient?
 
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