LED light bar installed - need to tap instrument lighting to illuminate switch?

[A4Audi]

Hi all,

I've recently installed a light bar behind the grill (hung from crash bar) and have the wiring all in order and operating. But, I have a switch that has a 4th lead to provide illumination to it. Even though the push-button latching switch is hot all of the time, I want to run that 4th wire so that it provides illumination when the lights are on (parking or ON). Any thoughts on what to tap into and where? I noticed the ESP light toggles with the instrument cluster lights, so that's a possibility since it's right there. But I wouldn't know where to tap...


My switch is here:
https://photos.app.goo.gl/aRnwt9hwwD5kFLbr8


And this is what illumination will provide:
https://photos.app.goo.gl/DvbCVydWs8n2Q7V6A



Thanks in advance.

[A4B8 2.0tfsi]

Well, why not take it from the headlights wire loom?

And why anyone would want to illuminate their ugly looking lightbars or other extra lights on the bumper, is beyond me. Looks ridiculous on every single car .

[Smac770]

He's looking for a line to power the illumination on the control switch. It's called term 58s. It's a PWM signal from the J519 with the duty cycle controlling the illumination intensity based on the interior lighting brightness (set by E20 dimmer knob in the headlamp switch). Any number of devices in the interior have that line, just splice to any of them. The cigarette lighter, the ESP button, etc. Will be a gray/blue wire.

[A4Audi]

He's looking for a line to power the illumination on the control switch. It's called term 58s. It's a PWM signal from the J519 with the duty cycle controlling the illumination intensity based on the interior lighting brightness (set by E20 dimmer knob in the headlamp switch). Any number of devices in the interior have that line, just splice to any of them. The cigarette lighter, the ESP button, etc. Will be a gray/blue wire.

Thanks for that info @Smac770! That's exactly what I was looking for. I'll try and that from right there in the console to make it nice and tidy.

A4B8 2.0tfsi - as stated, I'm not looking to illuminate the light bar... I like it perfectly hidden under the crash bar behind the grille, and readily available when needed (but not seen). I did pop out the headlight switch and was toying around with the 4 leads in that plug, but that didn't give me what I wanted. That's why I was inquiring for more info.

[Kolbenringe]

Well, why not take it from the headlights wire loom?

And why anyone would want to illuminate their ugly looking lightbars or other extra lights on the bumper, is beyond me. Looks ridiculous on every single car .

You've apparently not driven the E4 anywhere north of Sundsvall, the Arctic part of Sweden, Norway, or Finland. Alaska has some similarities.

Have you seriously not seen all the cars with lightbars on the bumpers in your own country? I drive from south Germany to Lyngenfjorden a couple times a year and I go over the E4, so I see all the Swedish cars with lightbars and there absolutely is a need for them.

[A4B8 2.0tfsi]

You've apparently not driven the E4 anywhere north of Sundsvall, the Arctic part of Sweden, Norway, or Finland. Alaska has some similarities.

Have you seriously not seen all the cars with lightbars on the bumpers in your own country? I drive from south Germany to Lyngenfjorden a couple times a year and I go over the E4, so I see all the Swedish cars with lightbars and there absolutely is a need for them.

You need to read my post again... I'm talking about illuminating your auxiliary headlights. Not the actual and vital benefits of turning the night into day.

[Kolbenringe]

You need to read my post again... I'm talking about illuminating your auxiliary headlights. Not the actual and vital benefits of turning the night into day.

Show a pic because I have no clue what you're talking about.

[A4B8 2.0tfsi]

If you are clueless about illuminated auxiliary lights and how they look, you could benefit from a minut of google time.

[Kolbenringe]

If you are clueless about illuminated auxiliary lights and how they look, you could benefit from a minut of google time.

Google what you told me to search for and post a screencap from google images. Again, no idea what you're crying about in your statement here:

"And why anyone would want to illuminate their ugly looking lightbars or other extra lights on the bumper, is beyond me. Looks ridiculous on every single car ."

I think there's a mismatch in what you think you're saying and what you're actually saying.

[A4Audi]

@Smac770 - thanks again!

I was able to pull the plug to the ESP switch, pop it open, and piggyback off of the (J519 circuit) gray/blue wire to get illumination with lights on. Now they illuminate when the light switch is on, and the red LED in the switch even adjusts brightness with the rest of the dash lights.

Very pleased with the outcome.
*The switch's red light here in the photo color looks different to the camera, but to the eye it's very, very similar.


Also, @Kolbenringe - I think what's being referred to here is low-level illumination or 'pre-illumination' that you often see on off-road /rally vehicles. I see this on Jeeps and other large trucks, where they typically keep the lights 'warmed up' at a very low level so that when they turn them on they aren't going from cold to hot immediately; better for longevity.

I think this is usually seen with halogens and traditional off-road / rally lights, but I have noticed that some light bars now offer this low level lighting - Rough Country light bars even offer a DRL strip down the middle of the bar (white or amber). It seems a bit pointless to me, other than just advertising that you have extra lighting (but Jeep drivers often have that type of ego... )

[Kolbenringe]

@Smac770 - thanks again!

I was able to pull the plug to the ESP switch, pop it open, and piggyback off of the (J519 circuit) gray/blue wire to get illumination with lights on. Now they illuminate when the light switch is on, and the red LED in the switch even adjusts brightness with the rest of the dash lights.

Very pleased with the outcome.
*The switch's red light here in the photo color looks different to the camera, but to the eye it's very, very similar.


Also, @Kolbenringe - I think what's being referred to here is low-level illumination or 'pre-illumination' that you often see on off-road /rally vehicles. I see this on Jeeps and other large trucks, where they typically keep the lights 'warmed up' at a very low level so that when they turn them on they aren't going from cold to hot immediately; better for longevity.

I think this is usually seen with halogens and traditional off-road / rally lights, but I have noticed that some light bars now offer this low level lighting - Rough Country light bars even offer a DRL strip down the middle of the bar (white or amber). It seems a bit pointless to me, other than just advertising that you have extra lighting (but Jeep drivers often have that type of ego... )

Yep. this is why I'm wondering what this guy is crying about, especially since where he lives we're required to have headlights on at all times, but it's now tolerated to use some form of DRL (ie: the lightstrips on B8/8/5 headlights or a lightstrip on an LED driving light bar). This is a great feature that reduces power consumption and increases visibility. In the Nordic countries, when it's dark, it's really dark and the material on the roadways isn't like what is used in central Europe where there is some level of reflectivity that you don't realize until it's not there. Roadways I've driven in Norway, Sweden, and Finland are pretty non-reflective adding to the lighting issue, even with great headlights. I really noted this a few weeks ago coming back from the Arctic and the moment I came back to Germany, I noted how much easier it was to see on non-lighted roadways. Trucks are often using the low-power illumination as well.

I don't know what the big deal is because even as a kid in the 80s I'd see low-power illumination in incandescent headlights, DRLs slowly creeping in, HIDs would have a small, incandescent side light to illuminate the reflector and act as a DRL, then off-road vehicles always had them and it's for visibility, not only for the people in the vehicle, but so that other vehicles have the best chances to know there's another one there, even without the crazy lights on. In overlanding, this is actually a thing and the aux lights can be used for when one is sitting around the vehicle and camping in some situations, so I don't really think it's a Jeep thing. In the Nordic countries, people are using these as their DRLs.

For my next drive, I want a small lightbar, or better, some sort of pencil beams that replace the fog lights, but I don't think the latter are available.

[A4Audi]

In the Nordic countries, when it's dark, it's really dark and the material on the roadways isn't like what is used in central Europe where there is some level of reflectivity that you don't realize until it's not there. Roadways I've driven in Norway, Sweden, and Finland are pretty non-reflective adding to the lighting issue, even with great headlights. I really noted this a few weeks ago coming back from the Arctic and the moment I came back to Germany, I noted how much easier it was to see on non-lighted roadways. Trucks are often using the low-power illumination as well.

For my next drive, I want a small lightbar, or better, some sort of pencil beams that replace the fog lights, but I don't think the latter are available.

@Kolbenringe - related to the switch that I was attempting to illuminate, I've been attempting a lighting transformation on my B8 A4 Avant. I've just added the light bar that was mentioned, but also just replaced the halogen headlamp housings with the bi-xenon headlamp housings. I'm also going to be replacing the D3S HID bulbs with D3S LED bulbs tomorrow - hopefully a much cleaner, brighter, whiter output, but much more focused than the halogens (even though I had upgraded to LED bulbs).

I also recently swapped my factory fog light housings for the Morimoto LED optic fog lights. I say 'optic' because they are a brand new housing and integrated lens/optic with LED, not just a LED replacement bulb. I'm a little disappointed with the light output, but they are WAY more focused than the factory housing; they have that sharp horizontal cutoff like the xenon projectors.

All of this effort is, of course, because it IS so dark in AK at this time of year, and substantial lighting is necessary for avoiding moose! If you can see them 1 second sooner, it can make all the difference.

• New DRLs are much brighter.
• New projector housings are much more focused.
• New light bar (spot) sends a fantastic shot of light down the road.

I'm also planning on putting 6-8" single row LED flood bars on those lower side grilles, just inside (up top) of the fog lights. I'm hoping to light up the sides, maybe angled out about 5-10° each so that the main light bar covers the forward light and the minis cover the sides.

[Kolbenringe]

@Kolbenringe - related to the switch that I was attempting to illuminate, I've been attempting a lighting transformation on my B8 A4 Avant. I've just added the light bar that was mentioned, but also just replaced the halogen headlamp housings with the bi-xenon headlamp housings. I'm also going to be replacing the D3S HID bulbs with D3S LED bulbs tomorrow - hopefully a much cleaner, brighter, whiter output, but much more focused than the halogens (even though I had upgraded to LED bulbs).

I also recently swapped my factory fog light housings for the Morimoto LED optic fog lights. I say 'optic' because they are a brand new housing and integrated lens/optic with LED, not just a LED replacement bulb. I'm a little disappointed with the light output, but they are WAY more focused than the factory housing; they have that sharp horizontal cutoff like the xenon projectors.

All of this effort is, of course, because it IS so dark in AK at this time of year, and substantial lighting is necessary for avoiding moose! If you can see them 1 second sooner, it can make all the difference.

• New DRLs are much brighter.
• New projector housings are much more focused.
• New light bar (spot) sends a fantastic shot of light down the road.

I'm also planning on putting 6-8" single row LED flood bars on those lower side grilles, just inside (up top) of the fog lights. I'm hoping to light up the sides, maybe angled out about 5-10° each so that the main light bar covers the forward light and the minis cover the sides.

ahhhh, in link three now I know what you mean. I don't see those out here, since we have very strict lighting laws in Germany. In the Nordic countries, there are now similar-looking LED bars that somehow sandwich between the license plate and the bumper cover and hang under the license plate. That's an option for me, but I would prefer pencil beams where the fogs go. Alaska has significant similarities (I'm from the US) to the more northern reaches of the Nordics, including moose. I've had a few incidents myself.

My car has the factory bi-xenons with the automatic system that works kind of ok, I guess. The problem with these cars always has been that the low beams are adjusted so incredibly low that there's no distance lighting, so I adjust them up again after inspection when they adjust them back down. I guess they want one to use the auto dynamic headlight setting where the high beams turn on, but the system turns them off so often due to other traffic in the distance that it's not really the best solution.