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Discussion Starter #1
Hello everyone! I have spent a few hours on separate occasions searching for answers on different forums and trying to find solutions, but to no avail. I can find bits and pieces of what I need to know, but nothing exact.

I was riding in my buddy's Porsche 911 Turbo a few months ago and was impressed with his illuminated door sills. So I got to thinking.......I can do that on my OBXT! I have all the materials purchased, and won't have a problem making the door sills. The only problem I have is the electrical part. I can solder, but I have no clue what to solder the lights to. I've got the puddle lights on my doors and may just tap into that source. But I've been reading other closely related threads about doing LED strips on the footwells, and some have come to the conclusion that tapping into the BIU would be the best source.

So here's my question: Does anyone have experience tapping into the BIU? I'm reluctant to just start screwing with it before I ask someone, because the part to replace it is quite pricey. If not, has anyone tapped into the puddle lights on the door? If so, do any of you have diagrams or have you seen threads with good directions on how to accomplish this? Any help/insight is greatly appreciated! Thanks!
 

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Cool idea, but wouldn't you have to re-program the BIU/computer to tell it to light up the door sills when the doors are open? That sounds so complicated. Tapping into the puddle light wiring seems much, much easier.
 

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Discussion Starter #3
That's the part I'm completely confused about. Sounds like a great idea, but the logistics of it aren't straightforward. I'm guessing what people have done is tap into a feed wire/line to the BIU the same way you would with the puddle light wires. Nonetheless, I'm still open to ideas. I simply want the lights to come on when I open the door.

I could also tap into the dome light, but that seems like a heck of a lot more work than I need to do to accomplish my goal...
 

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Discussion Starter #4
Bump 'n Grind....

Any insight anyone? Dig deep people!!! Maybe I can broaden the questions: "How can I make the lights on my project turn on when I open the door? Would you tap into the BIU or into the puddle lights on the door?"

Let me sweeten the pot: I'll buy you a six pack. (If you come to MT.)
 

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I don't get it, why don't you want to tap into the door puddle lights? Are you afraid that opening the door will be complicated? I can tell you that it is not difficult at all. It is quite easy, in fact.

Also, you may not even have to open the door. Just use a continuity meter to touch one probe to the bulb socket and then you can poke around with the other probe to see which wire corresponds to it under the dash right before the harness enters the door.

Then, you can tap the wire straight from under the dash, under the carpet, and to your door sill. What's the big deal? :confused:
 

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Not sure what you mean by "tapping into the BIU". I raise this because the door step light (puddle light) and the cabin interior dome light are controlled differently. This is apparent from the fact that, for example, when the door is opened, both come on, but when the door is closed, the step lamp goes out immediately, whereas the dome light fades out slowly. (Similarly, if a door is left open, the step light will remain on indefinitely, possibly running down the battery, whereas the dome light will eventually be turned off by the BIU, helping to prevent battery drain.)

The difference is that the dome light (along with others) is controlled by the BIU, whereas the step light is switched on and off solely by the door switch.

Both the step light and the dome light are connected to an always-on 12 V source. The low side of the step light goes to the door switch, which, when the door is opened, connects the low side to ground, closing the light's circuit and turning on the bulb. The low side of the dome light (when switched for "door" operation) goes to the BIU. The BIU provides the ground path to turn the light on and controls the current through it to slowly dim the light when the door is closed. The BIU is also connected to the door switch so that it "knows" when the door is opened and then closed based on whether the door switch is open (door closed) or closed (door open).

To get an added light to work, you would have to provide it with always-on 12 V power, and connect the other side to either the door switch line or to the BIU line that grounds the dome light, depending on how you want the added light to work.
 

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power from any of dozens of power sources under the dash or straight from the battery.

run the power through a relay to the lights you want to power.

then have the door switch signal trip the relay.
 

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Discussion Starter #8
Haha, I'm quickly finding out that I am deficient in my knowledge of electrical systems in vehicles (to put it nicely.) As I said before I can pretty much do anything else, but this electrical jargon is baffling. All I ask is to be patient.

And thank you all for taking time out of your day to help with my inexperience. :)

mike552, since I want the lights to only come on when the door is open, I my knee-jerk reaction was to assume that I should just tap into the existing light doors. I only brought up the BIU because I had seen it utilized in other threads. I have no doubt that it can be used (maybe by someone that has a tad bit more experience), but I am coming to the conclusion that might not be the best way to go. Even though I've never had the door panels off on this Subie, Ive had them off in all of my other cars, so I have no aversion to taking the doors off. But I like your straightforward idea of testing to see which wire is the door light and tapping in to that source under the dash. "The big deal" is the fact that I've just neveer done this stuff before, haha. Seriously, I'm a noob when it comes to electrical. Mechanical work I'm ok with. Electrical and body, get me a doctor, haha. Thanks for your reply.

plain OM, So what I'm hearing is that I can just tap into the dome source or door source? I want the light to stay on as long as the door is open, so the door (always-on 12-v) source is the winner, it sounds like. I am thinking people in other threads (adding footwell strip lighting to their Subies) were using one of the sources flowing into the BIU, such as the door or dome light wires. Your response was very informative, thanks!

grossgary, again - I'm new to this stuff, so I've never used a relay. From my limited knowledge, these are used as 1.) a switch, and 2.) a control over voltage, right? Or am I completely wrong on that? I'm looking for the easiest install and yours sounds like the more technical route. But if it is the right way to go, I will not skimp just because it is the harder way to go....I need to study up on relays a little bit, it sounds like. What I imagine is that when the door is opened, the door sill lights would come on. So using a relay would entail having a contact point on the door sill that is depressed to shut off the light, and pops out (when the door is open) to activate the light, correct?

Thank you all for your patience and responses. I ordered the parts yesterday, so I'm estimating they'll be here late next week. The project won't take up too much time, but I simply don't have a lot of time on my hands. I work 40+ hours a week and study about 30 - 40 hours a week. Needless to say, time is scarce. I estimate the project to be completed in 2 weeks, but as we all know, sh*t (oops, I mean LIFE) happens. I think I'll take photos of my progress throughout and post an update when it's all said and done with all the photos. I've had a few people say it's just a crappy idea, so I'd like to show them all wrong, haha.
 

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mike552, since I want the lights to only come on when the door is open, I my knee-jerk reaction was to assume that I should just tap into the existing light doors. I only brought up the BIU because I had seen it utilized in other threads. I have no doubt that it can be used (maybe by someone that has a tad bit more experience), but I am coming to the conclusion that might not be the best way to go. Even though I've never had the door panels off on this Subie, Ive had them off in all of my other cars, so I have no aversion to taking the doors off. But I like your straightforward idea of testing to see which wire is the door light and tapping in to that source under the dash. "The big deal" is the fact that I've just neveer done this stuff before, haha. Seriously, I'm a noob when it comes to electrical. Mechanical work I'm ok with. Electrical and body, get me a doctor, haha. Thanks for your reply.

plain OM, So what I'm hearing is that I can just tap into the dome source or door source? I want the light to stay on as long as the door is open, so the door (always-on 12-v) source is the winner, it sounds like. I am thinking people in other threads (adding footwell strip lighting to their Subies) were using one of the sources flowing into the BIU, such as the door or dome light wires. Your response was very informative, thanks!

grossgary, again - I'm new to this stuff, so I've never used a relay. From my limited knowledge, these are used as 1.) a switch, and 2.) a control over voltage, right? Or am I completely wrong on that? I'm looking for the easiest install and yours sounds like the more technical route. But if it is the right way to go, I will not skimp just because it is the harder way to go....I need to study up on relays a little bit, it sounds like. What I imagine is that when the door is opened, the door sill lights would come on. So using a relay would entail having a contact point on the door sill that is depressed to shut off the light, and pops out (when the door is open) to activate the light, correct?

Thank you all for your patience and responses. I ordered the parts yesterday, so I'm estimating they'll be here late next week. The project won't take up too much time, but I simply don't have a lot of time on my hands. I work 40+ hours a week and study about 30 - 40 hours a week. Needless to say, time is scarce. I estimate the project to be completed in 2 weeks, but as we all know, sh*t (oops, I mean LIFE) happens. I think I'll take photos of my progress throughout and post an update when it's all said and done with all the photos. I've had a few people say it's just a crappy idea, so I'd like to show them all wrong, haha.
The easiest way to add a light is just as you describe - tapping into an existing light and adding in a new light. That will work fine for most things. Sill lights probably don't use up a whole lot of power at all (They are LEDs, I imagine?). You can drop those in there and have no issues at all. In fact, a relay is probably a waste when we're talking current draws that small.

For other installations (many lights or higher-current lights, like puddle lights, aux headlights, amplifiers, etc), you have to consider how much current is being drawn and what it will do. If a circuit is meant to operate a tiny door light and you add a huge mess of stuff to it, you could blow a fuse, or worse: burn out a wire, connector, or even the control module. Even if it does work at first, you'll have to wonder if today is the day where it stops working.

For those applications, relays are the way to go. A relay is a mechanical switch controlled by an electrical signal. You still tap into the door lights (or whatever trigger you want), but instead of pulling the power to run the lights off that line, you just use it to operate the switch. Minimal current needed, so minimal impact on the circuit. The switch itself can switch whatever you want! You can run a wire directly to the battery and switch that, powering 200W aux driving lights, or your amplifier, or whatever else you want (make sure to use wiring and fuses that are appropriate for the application).

A third option is actually the one I'd recommend, but I don't know if it's an option in the subaru without looking in the fusebox. If there is a fuse specifically for the door lights, you can go to an auto parts store and get what's called an "Add A Fuse" kit and use that (Google for Add-A-Fuse to see what I mean). What they do is replace an existing fuse in your fusebox with 2 fuses - one is the original fuse, the other is a new fuse that comes with a wire you can attach to. That should give you the benefit of a relay without having to actually wire one up. Again, I don't know if the door lights are actually on their own fuse or not.
 

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Can I back this up a bit for a moment . . ?

I've noticed that two terms are being used in regard to the desired lighting: "door sill" and "footwell". These, at least to me, are two different areas. I can understand lighting up the foot well area (the floor area of the front seats), but not the door sill (the part of the car body at the bottom of the door opening, more or less the top of the rocker panel). What is it that the Porshe has that's so desirable?

If it's lighting for the front seat area, have you tried the map lights? They light up a good part of that area, but in the 2007 don't come on with the dome light when the door is open. (That was added, I believe, in 2008.) However, there apparently is a mod for this. See this thread in the LegacyGT forum: http://legacygt.com/forums/showthread.php/map-lights-dome-light-mod-23139.html?t=23139&highlight=dome+light (It's a long thread but worth reading through as follow-up posts provide additional ideas and experiences.)
 

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Discussion Starter #11
The easiest way to add a light is just as you describe - tapping into an existing light and adding in a new light. That will work fine for most things. Sill lights probably don't use up a whole lot of power at all (They are LEDs, I imagine?). You can drop those in there and have no issues at all. In fact, a relay is probably a waste when we're talking current draws that small.

For other installations (many lights or higher-current lights, like puddle lights, aux headlights, amplifiers, etc), you have to consider how much current is being drawn and what it will do. If a circuit is meant to operate a tiny door light and you add a huge mess of stuff to it, you could blow a fuse, or worse: burn out a wire, connector, or even the control module. Even if it does work at first, you'll have to wonder if today is the day where it stops working.


For those applications, relays are the way to go. A relay is a mechanical switch controlled by an electrical signal. You still tap into the door lights (or whatever trigger you want), but instead of pulling the power to run the lights off that line, you just use it to operate the switch. Minimal current needed, so minimal impact on the circuit. The switch itself can switch whatever you want! You can run a wire directly to the battery and switch that, powering 200W aux driving lights, or your amplifier, or whatever else you want (make sure to use wiring and fuses that are appropriate for the application).

A third option is actually the one I'd recommend, but I don't know if it's an option in the subaru without looking in the fusebox. If there is a fuse specifically for the door lights, you can go to an auto parts store and get what's called an "Add A Fuse" kit and use that (Google for Add-A-Fuse to see what I mean). What they do is replace an existing fuse in your fusebox with 2 fuses - one is the original fuse, the other is a new fuse that comes with a wire you can attach to. That should give you the benefit of a relay without having to actually wire one up. Again, I don't know if the door lights are actually on their own fuse or not.

I am using an LED light strip. it has 3 LED pods that I am sectioning, probably 9 - 15 low-power LED's altogether. From what I understand, these would draw a minimal charge. If I tapped into the door light, I'm guessing I'll be ok, especially because I traded in LED festoon bulbs in the door. (Maybe guessing is a dangerous thing with my lack of knowledge.) But again, I assume that with the existing door light + door sill lights, I'm still drawing less current than the original door bulb by itself.

I will Google the add-a-fuse option. Sounds like a pretty straight-forward option to me, yet may take a little longer than splicing into the existing wiring. I'll look into it tho. Thanks for the info, very informative!
 

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Discussion Starter #12
Can I back this up a bit for a moment . . ?

I've noticed that two terms are being used in regard to the desired lighting: "door sill" and "footwell". These, at least to me, are two different areas. I can understand lighting up the foot well area (the floor area of the front seats), but not the door sill (the part of the car body at the bottom of the door opening, more or less the top of the rocker panel). What is it that the Porshe has that's so desirable?

If it's lighting for the front seat area, have you tried the map lights? They light up a good part of that area, but in the 2007 don't come on with the dome light when the door is open. (That was added, I believe, in 2008.) However, there apparently is a mod for this. See this thread in the LegacyGT forum: http://legacygt.com/forums/showthread.php/map-lights-dome-light-mod-23139.html?t=23139&highlight=dome+light (It's a long thread but worth reading through as follow-up posts provide additional ideas and experiences.)
Sorry, dude. I am horrible at turning cerebral discourse into written sentences. No wonder why I confused you...

The footwell lighting references were in other threads by people who were trying to light up the footwell area with LED strips. Some of them only wanted the footwell lit up when the doors opened, (exactly like my requirement for my door sills), hence my reference to them. So you're right, the footwell and door sill were/should be referred to as seperate areas of the vehicle. So we're still on the same page - the door sill is the door sill, and the footwell is where the driver and passengers stow their feet while they're in the car.

I actually do have the dome light that turns on with the open door - I've got the Limited, homeboy! I'm rollin' trump-style up in this lezbaru, son! haha...I appreciate the thought/link, though! I traded out all the interior lights (dome front, dome rear cargo, map lights, and puddle lights) with 'cool white' LED's, and I'm thoroughly impressed with it. Seems like a small thing, but makes the interior feel like a million bucks. (Don't ask me how a million bucks feels, because I am too poor to know.)
 

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Discussion Starter #13
UPDATE:

I got some of the stuff in the mail today. Why it took so long, I have no clue. What I received: Red LED strip, White LED strip, and resin dye. I'm still missing the actual hardening epoxy casting resin, so I hope it will be here tomorrow. Part of the reason I'm posting these lame pictures is because I have never uploaded pics via another site (I'm chose Photobucket), so this posting is my lab-rat. Without further adieu, here's the hardware:

This is the dye for the casting resin. Without this dye, the poured resin will be clear. I'm going for an opaque look.


Hmmm....what are these little delights? Well the two items on the left are the LED light strips (each 16 feet long). The bottle on the right is the dye from the above pic.


A closeup of the LED strip. They are grouped in clusters of 3 LED's, so you can cut them down to size.


And finally, here is a picture of my stock door sill plate. Since this is my first picture posting, I'm not sure what size the pictures will be or in what resolution. I apologize in advance if I FUBAR'd this. Anyway, I'm taking a dremel tool to this sill plate. I will cut out each SUBARU letter, which will be backlit by the red LED's. The white LED's are for on each side of the lettering where there are vertical dashes. I'm cutting each individual one out. In the end I'll have (very opaque) white dashes, red lettering, then white dashes again. Check it out:



Wish me luck!
 

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Discussion Starter #14
By the way, does anyone know how to change the name of their own thread? I can't seem to find how to do this, and I've also searched other threads for it...
 

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Ok, next logical question for a clueless guy.......yep! You guessed it: "Where do I find a moderator?"

Before I get a lot of honkies typing, "S***, son! Get a clue," maybe I'll get lucky and have a mod see this thread...
 

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Just an update, I finally received my casting epoxy in the mail from Amazon! It comes in 2 bottles of liquid (I purchased the brand Castin' Craft, same brand as the pigment in the picture above.) One bottle is the epoxy (clear in color) and the other is the hardener (off-white in color.)

Here's the unfortunate news - I'm leaving tomorrow for business meetings in Seattle for a full week. Son of a b****! Does my boss not know how anxious I am to start this project? And thanks to Amazon, my delivery was a week late. Sweet! Anyway, I'll break out the dremel tool next week and take some pictures. Again, I've had a few people call me crazy, saying this won't work. I simply said, "I'm an American, and I manufacture s***." Can't wait to show them the finished project.

BTW, PM'd a mod and still no answer...
 

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Mod's get busy sometimes.

I'm going to ask a stupid question that no one else brought up yet:

Doesn't the door switch have power running through it? Doesn't that wiring already run through the sill plate? I would want to double check what is on that circuit, but to me that seems like the most logical place to start for this project?
 

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Doesn't the door switch have power running through it? Doesn't that wiring already run through the sill plate? I would want to double check what is on that circuit, but to me that seems like the most logical place to start for this project?
Door switch is on the ground side of the lighting circuits. See my description in post #6, and attachment (below is 2011).
 

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