Recommendations needed for 1995 Previa LE S/C All Trac front and rear fog lights

[Alaric Darconville]

My 1995 Previa LE with All Trac and factory supercharger has proved to be a very capable ice/snow vehicle, at least as compared to my 2001 Corolla LE. For this reason, it has become my heavy weather vehicle of choice, and I'd like to outfit it with fog lights and a single rear fog light, and need some assistance in picking the right set as well as rules guidelines for mounting them.

I do know that I'd prefer not to just order a set of factory headlights with the fog lights built in, unless it is documented that they actually work well (most factory foglights seem to be little more than $350 toys).

Also, concerning the wiring, I want all three fog lights to temporarily extinguish when I pull on the stalk to flash the high beams, and then reactivate when the stalk is returned, but to require a manual restart if I throw the high beam lever forward (the assumption is that I would use a temporary high beam flash to view high-mounted signage or just to test if the backscatter would be too much to stay on high beams, but if I throw the lever into the normal high beam position that means I've decided to keep them on for a while, ie conditions no longer warrant the use of fog lights).

I suppose the constraints of the original electrical system may not allow it to function exactly so; at the very least, then, I want to the fog lights to turn off and stay off when the high beams are activated-- self-reactivation is not the biggest deal to me (I recall a BMW commercial in which a BMW, driven in CLEAR WEATHER, has the fog lights on, and when the driver passes another vehicle he flashes the high beams. At the time, it really impressed me (I was 15) but now it's just a complication without real need, and I know the fog lights were on unnecessarily in the first place).

I also want them to require that the low beams be turned on before they can be activated; I hate seeing cars with their fogs and parking lights on in clear weather and don't want to be that 'jerk'. Besides, if the fog is THAT bad that they get that much backscatter from their low beams, they should probably not be driving. (These are the same jerks that use their fog lights 24/7 -- including in clear weather, which really irks me -- yet can't be troubled to make sure their license plate lights are working. They also zoom along well over the speed limit, as if fog lights exempt them from the Basic Speed Rule.)

I would assume that since the rear fog lamp is a conspicuity lamp, that a properly designed LED unit would be perfect for that. I did choose a single rear fog lamp because it would be less likely mistaken for a pair of brake lights, and that the "distance information" provided to other drivers by a pair of lights would not be enough of a benefit to justify it.

I plan on mounting the rear fog lamp on the bumper itself (fairly high on the bumper but not to interfere with the operation of the back hatch) and at least 5" away from the nearest illuminated edge of the factory taillights, and to the left of the vehicle centerline (probably in line with the driver's seat headrest, so it is clearly not confused with the CHMSL). The front fog lights will be mounted on the bumper, with the tops of the lenses below the top edge of the bumper. I plan on using selective yellow.

I also want to get better headlight bulbs while I'm at it. I assume that these are still the king of the road for H4 lamps: http://store.candlepower.com/90h4hbxtpo.html . I'm not sure if I'll also be able to afford to install relays for the headlights, but those and repolishing my headlamp lenses are also on my list (the repolishing part is cheap and easy, at least).

Any recommendations? Recommendations to get HID 'kits' or HID fog lights or anything sold by Lightforce will be summarily dismissed and potentially laughed at.

 

[Random Guy]

The Philips Xtreme Power H4 is the best and brightest standard wattage H4, but the 70/65W Osram +50 H4 is brighter. As far as the relays and heavy gauge wiring (at least 12 AWG, many cars have 18 or even 20 AWG wires for the headlamps) is a worthwhile upgrade, because output is exponential to the 3.5 power with voltage.

Regarding the wiring, if it were my vehicle, I would wire it so the fogs would work with either the parking lamps or the low beam headlights on. Switching to the high beams would cause the fog lamps to turn off. Switching back to the low beams would bring the fog lamps back on, unless you flipped the fog light switch back off, of course. It is easier to do it this way than the way you describe.

Don't worry about being one of those jerks who drives around with just their parking lights and fog lights on. That only makes you a jerk if you do it during clear weather. It is perfectly reasonable if the fog is thick as a brick.

On the subject of rear fog lights, I personally would go with 2. That is what my Volvo has, and as long as the nearest edge of the fogs is at least 10 cm away from the nearest edge of the brake lights (per ECE regulations), there should be no problems from someone not seeing your brake lights because your rear fogs are on.

BTW, it is my understanding that the rear fog lamps that went on European C5 Corvettes are fairly easy to integrate into the rear end of most vehicles.

Oh, and don't forget to send an email to Daniel Stern.

 

[Alaric Darconville]

The Philips Xtreme Power H4 is the best and brightest standard wattage H4, but the 70/65W Osram +50 H4 is brighter. As far as the relays and heavy gauge wiring (at least 12 AWG, many cars have 18 or even 20 AWG wires for the headlamps) is a worthwhile upgrade, because output is exponential to the 3.5 power with voltage.

I'd probably stick with stock wattages unless I do upgrade the wiring-- a higher wattage bulb may actually underperform compared to a stock wattage bulb if the voltage sags. There's also the risk of exceeding the factory wiring's capacity, especially considering the age of the vehicle and the potential for oxidation of junctions. Also, the higher wattage will just force my alternator (and ultimately, engine) to work that much harder.

Regarding the wiring, if it were my vehicle, I would wire it so the fogs would work with either the parking lamps or the low beam headlights on. Switching to the high beams would cause the fog lamps to turn off. Switching back to the low beams would bring the fog lamps back on, unless you flipped the fog light switch back off, of course. It is easier to do it this way than the way you describe.

That may be the easiest way-- I just have to be more conscientious to be sure I'm not the idiot in clear weather with fog lights on. The worst offenders seem to be drivers of 3/4 ton and larger trucks. It's bad enough that their headlights are mounted so high, but then they have fog lights mounted at seemingly the same height as normal car headlights adding to the glare. I guess they think all this extra light entitles them to blast past the drivers of smaller vehicles at about 15mph over the limit.

Don't worry about being one of those jerks who drives around with just their parking lights and fog lights on. That only makes you a jerk if you do it during clear weather. It is perfectly reasonable if the fog is thick as a brick.

I'm not sure if Oklahoma law permits only fog and parking lamps on-road, anyway. I'm not sure if the wise men who wrote the law know how it feels to be thick as a brick, but as I take my place in a wiser world of bigger motorcars, I wonder who to call on. (Had to respond to what appeared to be a Jethro Tull reference.)

On the subject of rear fog lights, I personally would go with 2. That is what my Volvo has, and as long as the nearest edge of the fogs is at least 10 cm away from the nearest edge of the brake lights (per ECE regulations), there should be no problems from someone not seeing your brake lights because your rear fogs are on.

BTW, it is my understanding that the rear fog lamps that went on European C5 Corvettes are fairly easy to integrate into the rear end of most vehicles.

The number of rear fog lights is somewhat of a matter of debate for me. While some would argue that one light makes it hard for drivers behind you to determine how quickly they are closing on you, it would seem that it would also be the case for motorcycles-- they get along with one taillight just fine. Not to say my mind is completely made up on this, though.

Oh, and don't forget to send an email to Daniel Stern.

I may just have to. For now, I guess I'm just getting ideas.

 

[Random Guy]

I definitely reccomend upgraded headlight wiring, as from what I have read, Toyota underspec's that. As far as the number of fog lights goes, I am also somewhat torn on the issue. Two fog lamps give following drivers distance information, as well as making you more noticable (twice as much light), and adds redundancy (two lamps instead of just one must fail in order to render you with no rear fog lights). On the other hand, two rear fogs do look just like two brake lights. It would also seem that if the weather is bad enough to where following drivers cannot see your rear parking lights, but they can see your rear fog lights, they not be going so fast that they need the distance information that two rear fogs give you. But, both the cars I have that have rear fog lights have two of them (A MB W123 300D, and a Volvo 940 wagon), so I am just going to stick with that.

 

[Alaric Darconville]

I definitely reccomend upgraded headlight wiring, as from what I have read, Toyota underspec's that.

Maybe that should be my first priority.

As far as the number of fog lights goes, I am also somewhat torn on the issue. Two fog lamps give following drivers distance information, as well as making you more noticable (twice as much light), and adds redundancy (two lamps instead of just one must fail in order to render you with no rear fog lights). On the other hand, two rear fogs do look just like two brake lights. It would also seem that if the weather is bad enough to where following drivers cannot see your rear parking lights, but they can see your rear fog lights, they not be going so fast that they need the distance information that two rear fogs give you.

The redundancy would be a good thing, but I was thinking the same thing about whether at those speeds or distances the distance information itself would be meaningful to the driver behind me. I guess I'm leaning towards one as it being less ambiguous.

One other thought is that having two rear fog lights ensures compliance and reduces confusion across jurisdictions where the handedness of traffic differs, such as a vehicle registered in the UK frequently being driven in France.

 

[tay]

Well, being that you are in the US, it would make sense IMO to go for two rear fog lights.

Most drivers here aren't used to seeing rear foglights, so having one light being brighter then the rest makes it appear like the CHMSL is on or that there are several bulbs burnt out on the rear of the vehicle.

With two rear foglights, drivers who don't know what they are will just think they're bright taillights, and not be as confused as they would if there was a single very bright red light on the back.

IMO, also, I'd consider getting a LED CHMSL from Daniel Stern or another reputable source. The instantaneous on/off is supposed to make it more conspicuous, and you want to make sure it is bright enough to be visible.

As for forward lighting, upgraded wiring harness is a must. They're relatively simple to make, and the difference is significant. Why use good quality bulbs if you're not giving them enough juice?

Stay far away from OEM foglights, they're just decorative. AFAIK, though, the proper protocol for the use of foglights is that they should be used in substitution to the lowbeams, not in conjunction with the low-beams. The reason being that they should only be used when the backscatter from the lowbeams becomes an issue, and while travelling at low speeds in thick fog. Not at normal speeds in addition to lowbeams in mild fog/rain/snow.

Just some food for thought... I'm not much of an expert, just thought you might want to consider these points or look into them a bit more.

 

[Alaric Darconville]

Well, being that you are in the US, it would make sense IMO to go for two rear fog lights.

Most drivers here aren't used to seeing rear foglights, so having one light being brighter then the rest makes it appear like the CHMSL is on or that there are several bulbs burnt out on the rear of the vehicle.

With two rear foglights, drivers who don't know what they are will just think they're bright taillights, and not be as confused as they would if there was a single very bright red light on the back.

The single rear fog lamp will be mounted low on the vehicle, and far to the left of center, so it shouldn't look like a CHMSL. And if it does, at least it was SEEN by the other driver.

IMO, also, I'd consider getting a LED CHMSL from Daniel Stern or another reputable source. The instantaneous on/off is supposed to make it more conspicuous, and you want to make sure it is bright enough to be visible.

That is another upgrade I've considered.

As for forward lighting, upgraded wiring harness is a must. They're relatively simple to make, and the difference is significant. Why use good quality bulbs if you're not giving them enough juice?

Agreed.

AFAIK, though, the proper protocol for the use of foglights is that they should be used in substitution to the lowbeams, not in conjunction with the low-beams. The reason being that they should only be used when the backscatter from the lowbeams becomes an issue, and while travelling at low speeds in thick fog. Not at normal speeds in addition to lowbeams in mild fog/rain/snow.

While I'm not licensed to practice law in the State of Oklahoma, Oklahoma State Statute Title 47, Chapter 12, Article 2, Section 12-17 states:

D. 1. A motor vehicle may be equipped with not to exceed two front fog lamps or two rear fog lamps which shall only be used when visibility, as described in paragraphs 3 and 4 of subsection A of this section, is limited to one-half (1/2) mile or less.

2. Front fog lamps shall be mounted on the same level on opposite sides of the front of the vehicle at or below the level of the headlamps. Front fog lamps may be used with lower beam headlamps or switch controlled in conjunction with the headlamps and may be used, at the discretion of the driver, with either low or high beam headlamps. Front fog lamps shall not be used in substitution of headlamps, when headlamps are required.

I believe some time ago, an exemption was given to using fog lamps without headlamps when conditions warranted it, but that is not stated in the current law.

 

[-Virgil-]

I do know that I'd prefer not to just order a set of factory headlights with the fog lights built in, unless it is documented that they actually work well (most factory foglights seem to be little more than $350 toys).

Well...what are you hoping to accomplish with front fog lamps? Most people grossly overestimate the utility of fog lamps. They can help you see the edges of the road close to the car so you can safely grope your way home through bad weather at very low speeds. That's all they can do. What kind of condition are your headlamps in? If they're less than perfect, you may want to replace them with new ones, in which case it would be worth your while to get the European-spec items instead of another set of the American-spec ones. You'd get glass lenses instead of plastic, a wider beam, and a sharper cutoff with less upward flare light, so particularly if you upgrade the headlight wiring and run the Osram 70/65w bulb, you'd likely not need front fog lights. A good source for worldwide-spec Toyota parts is http://cheaptoyotaparts.co.uk/ , write in and ask them for pricing on a set of RH-traffic (LHD) European '95 Previa headlamps without headlight levelling. That would be money much more effectively spent than on a pair of front fog lamps (any front fog lamps). I think I'd probably specify the European headlights without fog lamp, because they contain a larger (=better) headlight reflector than the ones with fog lamp.

Also, concerning the wiring, I want all three fog lights to temporarily extinguish when I pull on the stalk to flash the high beams, and then reactivate when the stalk is returned

Why would you want the rear fog to temporarily extinguish...? I can't think of a reason. Front fogs no problem, it would be easiest to have them extinguish when the high beams are used even intermittently as a flash (that is, it would be harder to have them remain lit through the duration of the high beam flash).

but to require a manual restart if I throw the high beam lever forward (the assumption is that I would use a temporary high beam flash to view high-mounted signage or just to test if the backscatter would be too much to stay on high beams, but if I throw the lever into the normal high beam position that means I've decided to keep them on for a while, ie conditions no longer warrant the use of fog lights).

Sounds like you're wanting the fog lamps to turn off if you go to high beam, and you don't want them to turn back on by themselves when you go back to low beam. That's a little more difficult than the standard installation, but not too much so; you'd need a "latching" relay and a momentary-contact switch for the fog lamps.

I would assume that since the rear fog lamp is a conspicuity lamp, that a properly designed LED unit would be perfect for that.

You can get an LED rear fog lamp if you want one. Truck-Lite makes several of them. There's the 45041R 3" x 5" oblong unit, or the 44120R 4" round unit. All kinds of mounting options for these, since they're designed to standard dimensions. You can mount them in the supplied rubber grommets in the bumper fascia or on a flange plate, etc. But it would be cleaner either to get the back light panel that includes rear fog lights from the European version of the Previa (see here). For that matter, I don't recall offhand, but doesn't the U.S. Previa also include a pair of extra brake lights in that full-width red plastic panel? If so, there's your solution without adding any new lamps -- U.S. brake light photometrics are identical to US/ECE rear fog lamp photometrics. There's a function splitter module you can get that lets you turn a brake lamp into a good working combination brake/rear fog lamp; Stern's got it (I got one from him a couple months ago) though he doesn't list it on his website), and there are probably brighter-than-stock bulbs you can use in there. Or another clean option would be to put in a rear fog lamp from an export-version C5 Corvette; see it
here and here. GM part number is 12533323 (left) and 12533324 (right). A reasonably competent GM dealer parts department should be able to supply it for you despite its "export" status.

I did choose a single rear fog lamp because it would be less likely mistaken for a pair of brake lights

Wise choice, IMO.

I plan on mounting the rear fog lamp on the bumper itself (fairly high on the bumper but not to interfere with the operation of the back hatch) and at least 5" away from the nearest illuminated edge of the factory taillights, and to the left of the vehicle centerline

Also a wise set of choices, IMO.

I'm not sure if I'll also be able to afford to install relays for the headlights

You should definitely do this before you spend money on front fog lights! Much better cost/benefit, even if you stay with the U.S. headlights. Relays will make a big difference even with standard-power (60/55w) bulbs, and a much larger improvement with 70/65w Osram bulbs.

repolishing my headlamp lenses are also on my list (the repolishing part is cheap and easy, at least).

Yeah...make sure you use a kit that also includes new durable hardcoat for the lenses, otherwise you're just scrubbing off the hardcoat and the polycarbonate lenses themselves will quickly degrade. I use this kit.

Any recommendations?

If you are bound and determined to have fog lamps, first figure out your maximum acceptable dimensions and how exactly you plan on mounting them rigidly (maybe on a LightWing?), then that'll determine what your choices are. I think in your position I would probably get a pair of PAR46 housings such as these (they also come in silver or black finish). There are scads of different lens-reflectors you can put in them. You can put fog beams (Bosch and Cibie have at various times made good fogs that fit these housings, don't know if they still do), you can put auxiliary low beams, you can put pencil spot beams, etc. A few years ago Stern had some interesting Hella H1 multi-focus European-code selective-yellow aux low beams with sharp cutoff. I didn't end up buying them (sold the truck I was going to put them on) but I probably would have, instead of fog beams, had I kept it. No idea if he still supplies them.

Recommendations to get HID 'kits' or HID fog lights or anything sold by Lightforce will be summarily dismissed and potentially laughed at.

YA DOOD U GOTS 2 GET 100000000K HID KIT'S THEY R SICK LOL

 

[Alaric Darconville]

Well...what are you hoping to accomplish with front fog lamps? Most people grossly overestimate the utility of fog lamps. They can help you see the edges of the road close to the car so you can safely grope your way home through bad weather at very low speeds.

That's pretty much my purpose. I'm not the guy speeding along in hellish weather conditions in my compensation truck, I'm the guy going "what an IDIOT!" when he goes by.

What kind of condition are your headlamps in? If they're less than perfect, you may want to replace them with new ones, in which case it would be worth your while to get the European-spec items instead of another set of the American-spec ones. You'd get glass lenses instead of plastic, a wider beam, and a sharper cutoff with less upward flare light, so particularly if you upgrade the headlight wiring and run the Osram 70/65w bulb, you'd likely not need front fog lights. A good source for worldwide-spec Toyota parts is cheaptoyotaparts.co.uk, write in and ask them for pricing on a set of RH-traffic (LHD) European '95 Previa headlamps without headlight levelling. That would be money much more effectively spent than on a pair of front fog lamps (any front fog lamps). I think I'd probably specify the European headlights without fog lamp, because they contain a larger (=better) headlight reflector than the ones with fog lamp.

That is an excellent idea. My lights are a bit hazy, and I think it's deep into the plastic or at least also on the surface of the side I can't reach and polish very well. Regarding getting them without fog lamps; I agree that most factory fog lights are toys, and I'd rather the fog lamps be below the headlight level instead of at them as they are in the Previa's design. Glass lenses certainly do appeal to me.

Why would you want the rear fog to temporarily extinguish...? I can't think of a reason. Front fogs no problem, it would be easiest to have them extinguish when the high beams are used even intermittently as a flash (that is, it would be harder to have them remain lit through the duration of the high beam flash).

Sounds like you're wanting the fog lamps to turn off if you go to high beam, and you don't want them to turn back on by themselves when you go back to low beam. That's a little more difficult than the standard installation, but not too much so; you'd need a "latching" relay and a momentary-contact switch for the fog lamps.

I was thinking of basing the reactivation of the fog lights based on which method I used to activate high beams. On the Previa (and most Toyotas in general), pulling back on the headlight stalk is the "flash" (which returns to the normal position by itself), and pushing it forward locks the high beams on.

The 'pseudo' "wig-wag" type of signal from a high beam flash (with the fogs coming back on automatically) could be a real attention-getter, I suppose, but then again, in weather where I'd truly need foglights I wouldn't be flashing my high beams at people for the most part.

But it would be cleaner either to get the back light panel that includes rear fog lights from the European version of the Previa. For that matter, I don't recall offhand, but doesn't the U.S. Previa also include a pair of extra brake lights in that full-width red plastic panel? If so, there's your solution without adding any new lamps -- U.S. brake light photometrics are identical to US/ECE rear fog lamp photometrics. There's a function splitter module you can get that lets you turn a brake lamp into a good working combination brake/rear fog lamp; Stern's got it (I got one from him a couple months ago) though he doesn't list it on his website , and there are probably brighter-than-stock bulbs you can use in there. Or another clean option would be to put in a rear fog lamp from an export-version C5 Corvette. GM part number is 12533323 (left) and 12533324 (right). A reasonably competent GM dealer parts department should be able to supply it for you despite its "export" status.

I'll have to check my own Previa for such a set of extra stop lights. It may be tempting, though, to actually use them as stop lights if they are not currently functional (but not actually as marker lights), although the CHMSL should already be good enough additional warning. Again, though, I may yet just use the one on the left side to help reduce ambiguity with the brake lights.

I'll have to investigate the splitter idea-- it seems like it might add some kind of ambiguity in and of itself, but I may have a misapprehension of how it works. There's a writeup on http://www.honda-tech.com/showthread.php?t=2481875 that I may be able to work from to fabricate such a solution myself. However, I will definitely work to avoid creating ambiguity at all costs-- the pictured Honda in that thread seems to just have one stop light stuck on.

Regarding choice of a single rear fog lamp and its placement
Wise choice, IMO.

Also a wise set of choices, IMO.

Thanks! I scoured forums and racked my brain trying to justify the number/placement, and recalled seeing a few cars in my time with single fog lights placed similarly.

On installing relays:
You should definitely do this before you spend money on front fog lights! Much better cost/benefit, even if you stay with the U.S. headlights. Relays will make a big difference even with standard-power (60/55w) bulbs, and a much larger improvement with 70/65w Osram bulbs.

Sold. Maybe not right away, but that's up on my list. The '01 Corolla LE could probably use it, too. I suppose that using relays would help increase the glare of my not-so-clear headlight lenses, though. I should probably install them at the same time I replace the lamps on the Previa, since I'm going to be poking around under the hood anyway.

Yeah...make sure you use a kit that also includes new durable hardcoat for the lenses, otherwise you're just scrubbing off the hardcoat and the polycarbonate lenses themselves will quickly degrade. I use doublehornproducts.com's kit.

I've been using Plast-X on the Corolla, and have to do it more frequently, it seems, as the remaining hardcoat (if any, I may be down to the lens itself) is weathering faster. I may order that kit for the Corolla before it's too late-- once the 'crazing' begins, it's all over. With the Previa, the above-mentioned glass replacement headlights would be a better bet than trying to polish and recoat them..

If you are bound and determined to have fog lamps, first figure out your maximum acceptable dimensions and how exactly you plan on mounting them rigidly. A few years ago Stern had some interesting Hella H1 multi-focus European-code selective-yellow aux low beams with sharp cutoff. I didn't end up buying them (sold the truck I was going to put them on) but I probably would have, instead of fog beams, had I kept it. No idea if he still supplies them.

So many options! I guess I have to weigh all of this against the age and mileage (156Kmi) of the Previa, too. The fog lamps do seem to be the least cost-effective at this point.

YA DOOD U GOTS 2 GET 100000000K HID KIT'S THEY R SICK LOL

Sadly, I see that sort of thing all too often. You hit it spot on with the apostrophe in the plural; it really captured the flavor of scionlife.com!

Thanks for your suggestions and your confirmation of some of my thoughts and hunches (and your contributions in general to the Automotive forum).

 

[tay]

The relays might be easier than you think. I guess you could replace the stock wiring, but it's cheap and easy to just augment it.

What you can do is just use a pair of relays (high beams and low beams), and wire their trigger coils to a single male socket which you can attach to the stock headlight female socket. Then just get a new pair of female sockets, and have the switch within the relay connect them to the battery positive and negative, through a fuse of course.

This is completely reversible. One afternoon is plenty of time to solder it all together, and it's something that can be installed/uninstalled in about 10 minutes. On my car, there are a pair of ring clamps for the battery post terminals, secured with a 1" long bolt. My harness has two ring terminals, so I just slip them over the ends of the bolt, attach a hex nut to keep them on, plug one male socket into my driver's side headlight connector (and pull the fuse for the passenger side), and then connect the female sockets to my headlight bulbs.

So, obviously, I'm a bit confused when you're speaking about being able to afford it. IIRC, my harness cost about $25 to make. Two ring terminals, about 10 feet of 12awg automotive wire, two 15A fuses, two standard automotive relays with sockets, and a few bulb connectors. It's far simpler than to upgrade the existing headlight wiring, although it does add a bit of clutter to the engine bay. If you were planning on rewiring your old stuff, this would be a much less complicated solution.

 

[Alaric Darconville]

The relays might be easier than you think. I guess you could replace the stock wiring, but it's cheap and easy to just augment it.

What you can do is just use a pair of relays (high beams and low beams), and wire their trigger coils to a single male socket which you can attach to the stock headlight female socket. Then just get a new pair of female sockets, and have the switch within the relay connect them to the battery positive and negative, through a fuse of course.

So, obviously, I'm a bit confused when you're speaking about being able to afford it. IIRC, my harness cost about $25 to make. Two ring terminals, about 10 feet of 12awg automotive wire, two 15A fuses, two standard automotive relays with sockets, and a few bulb connectors. It's far simpler than to upgrade the existing headlight wiring, although it does add a bit of clutter to the engine bay. If you were planning on rewiring your old stuff, this would be a much less complicated solution.

I recall seeing something about Toyota using a "ground-switched" system, so it may be a little more complicated. There's an article on danielsternlighting.com about the whole thing, I think. I'll probably go with 10 or even 8ga wire instead of 12 "just to be sure".

Monetarily, it may not seem like much, but there's also the time investment and being sure my soldering skills are up to the task. I suppose I could just spend a little extra and get a kit from Daniel Stern.

 

[-Virgil-]

Toyota uses much more than just a ground-switched system. It's a funky setup that must've been some Japanese engineer's fever dream. Getting headlamp relays to work right on a Toyota requires a mix of NO and NC relays -- I note Stern lists "Toyota" relay kits with a separate P/N than regular kits. But Tay's right -- you don't replace the stock wiring, you leave it in place to trip the relays.

Your linked Honda mod thread isn't as braindead as I feared it would be, but whoever wrote it is misusing the letter "D". Look at 'im throwing around terms like "EDM", "USDM", "UKDM", etc. D is for domestic, as in a Japanese car in the Japanese domestic (home!) market. A Civic in Europe is a European-market Civic, not an "EDM" Civic. Likewise with a US (not D) market Civic, a UK (not D) market Civic, etc. Minor nit to pick, I guess, but like the misplaced apostrophe, it telegraphs "I'm ignorant but I like to sound authoritative by using terms that sound all cool and jargon-y". As for his actual result, it's probably better than nothing, but it also probably does not meet rear fog photometry.

It is possible to set up the module previously mentioned in a manner so as to have the left and right rear aux lamps operate as brake lamps when the rear fog switch is "off", but have the left rear aux lamp burn steadily and the right rear aux lamp dark when the rear fog switch is "on".

 

[Alaric Darconville]

Toyota uses much more than just a ground-switched system. It's a funky setup that must've been some Japanese engineer's fever dream. Getting headlamp relays to work right on a Toyota requires a mix of NO and NC relays -- I note Stern lists "Toyota" relay kits with a separate P/N than regular kits. But Tay's right -- you don't replace the stock wiring, you leave it in place to trip the relays.

I figured as much about the relay situation-- it's not a whole rewire, it's just chaining them, as it were. Still, it'll take some doing to make sure that my own shoddy soldering won't negate the intended effect.

Your linked Honda mod thread isn't as braindead as I feared it would be, but whoever wrote it is misusing the letter "D". Look at 'im throwing around terms like "EDM", "USDM", "UKDM", etc... but like the misplaced apostrophe, it telegraphs "I'm ignorant but I like to sound authoritative by using terms that sound all cool and jargon-y". As for his actual result, it's probably better than nothing, but it also probably does not meet rear fog photometry.

I noticed that! I guess he thinks he's mad tite, yo. Also, the end result was actually pretty lame, at least on that vehicle. It just looked like one brake light was stuck 'on', since that particular assembly only had one stop/tail bulb in a single well.

I checked on my own Previa, technically the fog light would be within 10cm of the nearest lit edge of the brake lamp if I installed it within that (what appears to be) unused well in the whole light assembly. I'll have to investigate that when it's warmer. At least I was able to verify that both my license plate lamps are working. Burned out license plate lamps are a huge pet peeve of mine.

Q) How can you tell an approaching vehicle's license plate lamps are burned out?
A) It's a Civic with a 10,000K HID kit.

 

[tay]

Toyota uses much more than just a ground-switched system. It's a funky setup that must've been some Japanese engineer's fever dream. Getting headlamp relays to work right on a Toyota requires a mix of NO and NC relays -- I note Stern lists "Toyota" relay kits with a separate P/N than regular kits. But Tay's right -- you don't replace the stock wiring, you leave it in place to trip the relays.

Ground switched, positive switched, or some odd combination shouldn't matter, right? A bulb is a resistive coil of wire. A relay is also a resistive coil of wire, albeit a more resistive one.

I'm thinking in terms of an engineering "black box" - no matter how complicated the car's electrical system is, the output of the system is that one pin on the headlight socket is at an electrical potential 12-15v lower than the other pin in the headlight socket. How it gets that way should be irrelevant. The blackbox doesn't know whether that output is going to a bulb filament or a relay coil, so it should not matter at all. As long, of course, as the relay triger coil is electrically isolated from the rest of the system (which is the whole purpose of the relay in the first place) so that there aren't ground loops or anything goofy going on.

Of course, I may be wrong, but I don't see how two different "black box" electrical systems that both apply a voltage across a halogen bulb's filament could act differently if the filament is replaced with a relay's coil. The only difference between a coiled tungsten filament and a copper relay coil is the quantitative value of their resistance and inductance, not a fundamental difference that would allow a system that adequately powers one to be unable to adequately power the other.

 

[-Virgil-]

Ground switched, positive switched, or some odd combination shouldn't matter, right?

Wrong. The Toyota circuit has all kinds of tie-ins such that if you just put relays across the low beam + and - and the high beam + and -, stuff won't work right. You can get the lows remaining lit in high beam mode and/or the highs remaining lit when you switch back to low beam, you can get a nonfunctional dashboard high beam indicator, etc.

I appreciate your "black box" thinking, and it's correct in the case of many headlamp circuits...but not those in Toyota-made vehicles. Also not in those increasingly-common circuits that run the headlamps with PWM. Also not in those increasingly-common circuits that will not send power to a leg of the circuit on which filament resistance is not detected. In each of these cases, modifications have to be made to the simple "put relays across the + and - wires" idea. None of them are particularly difficult or complex, but without them, things won't work right.

Oh, and Alaric - who said anything about soldering?

 

[Alaric Darconville]

to Tay
Wrong. The Toyota circuit has all kinds of tie-ins such that if you just put relays across the low beam + and - and the high beam + and -, stuff won't work right. You can get the lows remaining lit in high beam mode and/or the highs remaining lit when you switch back to low beam, you can get a nonfunctional dashboard high beam indicator, etc.

I appreciate your "black box" thinking, and it's correct in the case of many headlamp circuits...but not those in Toyota-made vehicles. Also not in those increasingly-common circuits that run the headlamps with PWM. Also not in those increasingly-common circuits that will not send power to a leg of the circuit on which filament resistance is not detected. In each of these cases, modifications have to be made to the simple "put relays across the + and - wires" idea. None of them are particularly difficult or complex, but without them, things won't work right.

I knew I wasn't completely high! Tay's natural assumption would seem to be right, but having seen what Daniel Stern posted I knew I couldn't be too far off base.

Oh, and Alaric - who said anything about soldering?

Tay did:

One afternoon is plenty of time to solder it all together, and it's something that can be installed/uninstalled in about 10 minutes.

I suppose there are some very fine solder-free connectors and terminators available that would obviate the need to solder. There was a thread on here a while back (I think it was here) that described some interesting reusable connectors. I'll have to search for it, though. I recall that they were somewhat expensive but were also supposed to guarantee a much better connection than the typical crimp connectors one would find at Walmart.

 

[-Virgil-]

I don't use solder when I put together headlamp (or other automotive) harnesses. People argue back and forth over the relative merits and drawbacks of solder vs. crimp, but the clearly visible fact is that both methods work well if they're done properly with appropriate tools, components, and supplies. My reason for not soldering has nothing to do with any of that, it's because I can only make two things with a solder gun: burns, and a mess! One of these days/years I ought to sit down and practice until I can solder, but in the meantime, my crimped projects give good performance and durability.

I think the better connectors you have in mind are these ones.

 

[Alaric Darconville]

I don't use solder when I put together headlamp (or other automotive) harnesses. People argue back and forth over the relative merits and drawbacks of solder vs. crimp, but the clearly visible fact is that both methods work well if they're done properly with appropriate tools, components, and supplies. My reason for not soldering has nothing to do with any of that, it's because I can only make two things with a solder gun: burns, and a mess! One of these days/years I ought to sit down and practice until I can solder, but in the meantime, my crimped projects give good performance and durability.

I think the better connectors you have in mind are these ones.

I'm about the same way with a soldering gun or iron. My solder joints are definitely not the prettiest and sometimes turn out to be cold, which is a real pain.

The Posi-Tap ones are it! I'm a fan of allpar.com, and may be there that I first saw those connectors. I've also used the type of tap as seen on their review of an LED CHMSL (pictured at http://www.allpar.com/reviews/photos/third-brake-light/wiretap.jpg), and those are a bit weak to say the least. (Those are the ones available at Wal-Mart that I'd prefer not to use for something as high-current and 'mission-critical' as a headlight circuit.)

I'm definitely tabling the fog lights idea for now.

 

[tay]

The harness I'm using now is a mixture of crimps, spade terminals, and solder joints. It's a bit of a mish-mash thing. My connectors and relay sockets all came with a 6" or so pigtail that I just soldered. My ring terminals are crimped, though.

The important thing is keeping it waterproof. I used a tube of silicone to seal up the relay sockets, and to seal up the back of my 9004 connector (cheapo one that came with my "Spring" aftermarket headlights), while my H9 connectors have rubber boots included (purchased from ebay), and my H1 connectors also have rubber boots over spade terminals (cut out of a set of ZKW foglights). Solder joints are wrapped carefully with electrical tape. Important that it's waterproof. It's a bit of a mish-mash, but I have plenty of soldering experience, so it was no problem for me to just solder it. Crimps work just as well.

Yeah, I guess the bulb out warning indicators and DRLs and all that fancy stuff could cause problems. If you need an idiot light on your dashboard to know whether or not your headlights are functioning, you probably need to get your eyes checked.

 

[Random Guy]

Yeah, I guess the bulb out warning indicators and DRLs and all that fancy stuff could cause problems. If you need an idiot light on your dashboard to know whether or not your headlights are functioning, you probably need to get your eyes checked.

I don't know about other cars, but in 200, 700, and 900 series Volvos, the Bulb Failure Relay supervises the low beam headlamps, the rear parking lamps, and the brake lamps. It does this by comparing the current drawn by the left and right lamps. If it differs, the bulb failure light on the dash lights up. I believe the CHMSL is compared to dummy load. Therefore, if you pull the light for the bulb failure light from the instrument cluster, you lose the (very valuable) indication of a brake light being out.