What is this empty taillamp compartment?

I've been thinking of adding a rear fog lamp but before I fork $400 over to the local installer to cut open my trunk lid and transplant a Peterson 850F, I thought of looking at the factory taillamps to see if fog lamps can be more easily retrofitted.

I found this empty compartment on my taillamps. From the outside, it appears that there's no bulb or LED inside the compartment. From the inside, there's an arrow and a raised plastic circle, which indicates to me that this compartment accepts a bulb. The only bulb I can think of it accepting is a fog lamp bulb. However, this compartment is pretty much right up against the brake lamps. It's definitely not 4" away from the edges of the brake lights, which makes me question whether it's for a fog lamp bulb. It's pretty much adjacent with the brake lamps.

What is it exactly?

Car is an IS350c.

Album:

https://imgur.com/a/w7wYLOl

My guess that is for the rear fog lamp, but not for UNECE type-approved lamps. I'm unsure of the requirements in Japan for a rear fog lamp, but that compartment is way too close to the closest lit edge of the stop lamps to disambiguate the signal, tending to confuse other drivers as to when the driver is braking.

Japan uses UN ("UNECE", "ECE") lighting standards. Before that started being the case around 2007, there was no requirement for a rear fog lamp in Japan.

I can't tell what angle we're looking at in those photos of the lamp; which way is towards the rear of the car? I also can't tell (because it wasn't stated) what year IS350c it is. This time I went on a Google image hunt until I matched it up -- next time please provide more complete info with the question so others won't have to do homework to answer it, will you please?

The compartment you found is indeed used for the rear fog lamp in markets where it's required (that is, countries that apply UN Regulation 48), as on the Australian model shown in this picture, which zooms nice and large. The mystery of proximity to the brake light is easily solved now that we know this is the trunk lid light you're showing us, not the main light mounted in a fixed position on the car body. The brake light function from the trunk lid light is auxiliary/supplemental; the main brake light comes from the fixed lamp. US regs require that the brake light function be fully compliant as produced by the fixed-mount lamp. UN regs are more complicated on that front; they have what they call the "D lamps" and "Y lamps" which are two different ways of spreading a function across two or more separate lamp housings. The auxiliary/supplemental brake light function either isn't present on the UN-spec cars, or it's inactive when the rear fog is active.

So your waypath to installing rear fog lights is pretty simple, but won't be cheap unless you can find used parts: get the UN-spec inner rear lamp units which have the holes and cam-locks for the rear fog bulbs and sockets, and two of the socket/cable assemblies, and assemble the switching and wiring setup appropriately. If you want to be doctrinaire about it, put in a cutout relay so the supplemental/auxiliary brake light function on the trunk lid is disabled when the rear fog lamps are lit.

Hacking holes in the US-spec lamps and trying to kluge up the sockets will end in a river of tears and/or nothing resembling an actual rear fog light function. Either use the correct factory parts or forget it and put an 850F or two of these (for example...Perei, Hella, and Luxvision make a good variety of sizes and configurations) in the rear bumper fascia.

Oh, so it was the trunk lid lamp. The nature of that picture made it hard to tell what I was looking at.

Is it necessary to do it in pairs? Can't he save a little money by only getting the left side UN-spec inner rear lamp? Or is this a case where a pair of lamps is better than a single one in this instance?

Yes, one is better than none, but I think two would be better. I used to be something of a hardnose (or hard "other parts further south", LOL) in terms of preferring a single rear fog lamp, but there's a benefit to a 2-lamp system: other drivers can get a sense of how far they are from your car easier with two than with one. As long as they're not masking the brake light function there's no conflict -- and the ECE requirement for 4" separation is only one way to avoid masking, it's not the only way. I wouldn't worry about the rear fogs masking the brake light function in this case, even if the aux/supplemental brake light is left functional, the area lit up in bright red is going to grow quite a bit larger when you step on the brakes, with substantial brake light area well separated from the fog lights.

-Virgil- said:

other drivers can get a sense of how far they are from your car easier with two than with one.

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It would help them determine how rapidly they are closing in on you, but also the appearance of the other taillamps as they approach ("it was a single bright light but now I see it and the other tail lights") can give similar cues.

I don't suppose we really have any *data* on which method is better, so the debate does hinge on things like "not masking stop lamp function" and whether it helps determine distance and things like that.

One could upgrade the rear lamps one side at a time

-Virgil- said:

I can't tell what angle we're looking at in those photos of the lamp; which way is towards the rear of the car? I also can't tell (because it wasn't stated) what year IS350c it is. This time I went on a Google image hunt until I matched it up -- next time please provide more complete info with the question so others won't have to do homework to answer it, will you please?

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My apologies. I assumed that everyone would know that every IS250c/350c shared the same taillamps in every year of their production. That's probably not common knowledge...

Hacking holes in the US-spec lamps and trying to kluge up the sockets will end in a river of tears and/or nothing resembling an actual rear fog light function. Either use the correct factory parts or forget it and put an 850F or two of these (for example...Perei, Hella, and Luxvision make a good variety of sizes and configurations) in the rear bumper fascia.

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Thanks, didn't know that there were bumper mounted options. What about below-bumper mounted options? Is that a wise position? I read about one guy who always buys an E-code rear fog lamp from eBay.de and mounts it on the driver's side below the bumper. Too low to be helpful?

Too low means compromised line-of-sight and quick/easy accumulation of mud and slush.

I think I'm ready to tackle this project by myself instead of shelling over a few hundred of dollars to a shop that may or may not do a good job. They didn't even know what a rear fog was. I was thinking of wiring two of the Peterson 850F's to the interior trunk light, which is useless for me. The trunk light takes a festoon-type bulb, but I can't get it out the housing to figure out which type of bulb it is. From what I read online, interior festoon bulbs draw maybe 3 to 10 watts depending on the bulb.

I tried to find more information about the 850F but all the Peterson site tells me is that it works well from 9 to 24 volts. How many amps does it draw? I want to figure that out so I can figure out whether I can realistically wire two of the Peterson 850F's to the trunk light harness.

Ls400 said:

I tried to find more information about the 850F but all the Peterson site tells me is that it works well from 9 to 24 volts. How many amps does it draw?

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300mA at 13.8VDC, so a pair of them is still about 2/3rds of an amp.

You should pull a separate wire from the switch instead of trying to do something weird with the trunk light wiring.

Ls400 said:

I think I'm ready to tackle this project by myself instead of shelling over a few hundred of dollars to a shop that may or may not do a good job.

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So far so good...

I was thinking of wiring two of the Peterson 850F's to the interior trunk light

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What? No. You just got done saying you want the job done correctly. Leave the trunk like out of this -- it has nothing to do with the rear fogs, nor should it. Do the job correctly or don't do the job.

Yeah good idea, I left the trunk lamp alone. Instead of hard wiring, I decided to use a remote controlled relay. I have the relay attached to a small, lawn-mower type AGM battery in the trunk. The Peterson lights are attached to a sheet of metal from Home Depot with 3M double-sided tape. I just have to remember to charge the AGM battery every now and then.

Any pics of the finished install? The battery sounds like an unnecessary extra maintenance task,curious why you did not choose to just run a wire from fusebox to the trunk?

I couldn't find the channel to go from the fusebox to the trunk.

Finished install video:

https://imgur.com/a/k3PiEYf

It seems that those lamps are angled inward a few degrees. If you can't lay a level across both lamp faces without gaps at either of the vertical edges, they're not facing straight back. Also, they should be plumb from top to bottom (not aimed upward or downward).

It's easy to run a wire from the dashboard fusebox area to the trunk, by running it on the left side under the plastic trim under the doors. It's pretty easy to hide it that way. Much more reliable hardwired than using a separate battery in the trunk.

Also, it looks like you're able to activate them without any interlock, so you could accidentally activate them and not realize it, creating glare for others and inviting unwanted trips to the side of the road at the behest of the local constabulary.

Yeah, I have to go and drill a hole in the trunk lid and run the wire through that hole. Right now, the very thick wiring on the 850F's is forcing the lamps to be angled very slightly upward. I tried to bend the bracket on which they are mounted to form a shallow parabola to not smoosh the wiring on the back of the 850F's against the trunk lid. Once I find the cojones to drill two holes in my trunk lid I'll have everything aligned correctly.

I mounted an auxiliary reversing lamp and rear fog lamp under the bumper of an RX300 with some Grote brackets (compatible with the Peterson lamps/grommets):

Picture shows the tail, reversing (including auxiliary reversing lamp on the right side), and rear fog lamp (on the left side) all lit.

Blurry pic, eventually I'll have a thread up about the complete lighting job. The additional rear lamps aren't as far to their respective side of the vehicle as I'd wanted but the tailpipe and the trailer hitch interfered.

I'm thinking about putting this surface-mount Hella unit on my daughter-in-law's Altima. Don't ask me why they scrubbed the dimensions from the line drawings...maybe that information is on a "need to know" basis? Well, I need to know! This page has a much higher price, but it also has the dimensions in millimeters. Converts out to 11.19" wide, 1" tall, 0.43" thick (a little less than 7/16"), and 10.43" center-to-center screw holes.