A4 Underglow: The Forbidden Dream HELP

[reeselevitt]

I recently bought an B8.5 A4 and a friend of mine gifted me LED Underglow. I want to wire the underglow to my rear fog lights since I don't use them that often anyway, and it will give me an easy on/off switch. I am going into this blind and need all the help I can get, any pointers, tips, or knowledge is very much appreciated.

P.S: They are actual LED bars that I will be screwing onto the car, not floppy LED strips that'll have the adhesive fail in 4 days.

[japanada]

Find the fuse in the fuse box an add in a fuse tap for 3 bucks from autozone. Connect accordingly.

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[reeselevitt]

This sounds about 15x easier than what I was thinking in my head, thank you

[DrGER]

Find the fuse in the fuse box an add in a fuse tap for 3 bucks from autozone. Connect accordingly.

Front & rear fog lights are controlled directly by the comfort system control module -J393-, not the pushbutton switch in the dash. none of the exterior lights has its own switched fuse position.

[See later post re center dash switch assemblies] --g

[Smac770]

None of the rear lights are connected to any fuse. They are all directly driven by the J393.

Your post says it's B8.5, not B8.0. But does not say if it's sedan or wagon (allroad). Nor if it's incandescent or LED tail lamps. Can't talk specifics without all the specifics.

Do these aftermarket objects have a wattage or current draw rating?

[japanada]

None of the rear lights are connected to any fuse. They are all directly driven by the J393.

Your post says it's B8.5, not B8.0. But does not say if it's sedan or wagon (allroad). Nor if it's incandescent or LED tail lamps. Can't talk specifics without all the specifics.

Do these aftermarket objects have a wattage or current draw rating?

Well damn. Maybe find an interior light you don't use and wire into them? I don't know the last time I used my interior lights other than the visor...that's just me.

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[DrGER]

Depending on how invested you are in doing something like this, take a look at part #7 HERE.

Something like this switch panel for the right (passenger) side: https://www.ebay.com/itm/333628012862
Or this: https://www.ebay.com/itm/133743559371
Version J includes all three switch positions.

While I thinking of it & have the wiring diagram for 8K2-959-674-x open, terminal 1 (of the 8-terminal connector) goes to the left Parking Aid button and terminal 7 goes to the right window shade button.

[reeselevitt]

None of the rear lights are connected to any fuse. They are all directly driven by the J393.

Your post says it's B8.5, not B8.0. But does not say if it's sedan or wagon (allroad). Nor if it's incandescent or LED tail lamps. Can't talk specifics without all the specifics.

Do these aftermarket objects have a wattage or current draw rating?

It is a sedan and my tail lights are the stock LED, not sure if the rear fog light that is integrated into that assembly are incandescent or LED but i'd assume LED. As for the draw rating or wattage, I'll have to check when I get back home.

[Smac770]

The only incandescent bulb on the US B8.5 LED tails is the reverse bulb. If you're aftermarket device is expecting a stable 12v supply, I think you need to follow DrGER's lead and add a toggle to the dash to use as a control mechanism, and leave the tail lights alone.

The problem with the factory buttons above the climate controls are they are just momentary switches. The J519 makes note of the event and toggles the device state. The buttons do not latch. You'd need a latching relay connecting term 15 to the accessory, controlled by the button, to work - https://www.te.com/usa-en/products/r...?tab=pgp-story I say term 15 just to be certain the lights are only on when ignition is on; don't want the relay or control of it fritzing and passing term 30 endless until the battery is dead. But there's also plenty of undervoltage detection relays out there for cheap on Amazon, or pretty much anything you can make at the circuit level.

[reeselevitt]

Depending on how invested you are in doing something like this, take a look at part #7 HERE.

Something like this switch panel for the right (passenger) side: https://www.ebay.com/itm/333628012862
Or this: https://www.ebay.com/itm/133743559371
Version J includes all three switch positions.

While I thinking of it & have the wiring diagram for 8K2-959-674-x open, terminal 1 (of the 8-terminal connector) goes to the left Parking Aid button and terminal 7 goes to the right window shade button.

not sure how easy the removal to get there will be, but i will definitely look into doing that because having a button in the center to turn the underglow on/off would be amazing

[FourRingsC6]

I hard wired mine directly to 12v since mine has bluetooth box that I can turn on and off with my phone.



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[Smac770]

Or add the stop/start version of the coin holder - https://www.ebay.com/itm/382585740626
:-)

[reeselevitt]

Or add the stop/start version of the coin holder - https://www.ebay.com/itm/382585740626
:-)

If i were to add a stop/start coin holder would the port in the coin holder connect to an existing port below the coin holder or will I have to diy wire a connection to an open fuse that is ignition activated? hopefully my wording makes sense

[Smac770]

You're going to have to add a fuse and wiring regardless. I was just commenting on a factory looking button you could add for control purposes. None of the dash/console buttons are intended to pass sustained current. Did you ever see how much current these things you have require? Where is going to be your ingress point between the outside mounted devices and the inside of the car?

Something like this could be easy, just run it off the cig lighter, but I can't really tell how it manages the wiring. https://ultrabrightlightz.com/produc...on-dual-switch

What would be cool would be to use the cig lighter port, it's already wired for 10A, with an insert that is push in for on pull out for off. Take the ground line and run it to your device instead. Assuming you don't use the cig port for your charger. Modification of something like this would be cool, https://www.ecstuning.com/b-ecs-part...636ecs06-01~a/

[reeselevitt]

You're going to have to add a fuse and wiring regardless. I was just commenting on a factory looking button you could add for control purposes. None of the dash/console buttons are intended to pass sustained current. Did you ever see how much current these things you have require? Where is going to be your ingress point between the outside mounted devices and the inside of the car?

Something like this could be easy, just run it off the cig lighter, but I can't really tell how it manages the wiring. https://ultrabrightlightz.com/produc...on-dual-switch

What would be cool would be to use the cig lighter port, it's already wired for 10A, with an insert that is push in for on pull out for off. Take the ground line and run it to your device instead. Assuming you don't use the cig port for your charger. Modification of something like this would be cool, https://www.ecstuning.com/b-ecs-part...636ecs06-01~a/

It didn't come with much info but from what I can gather from it, it requires a 12v source and has a current max of 6amps. and im not sure where im going to route wires into the car but i've been reading up on ways to do so. Im thinking of possibly going through the ECU, but i'm having trouble finding a source with a guide to do so. I also have to make sure the wires dont go anywhere near anything too hot that could melt them.

[reeselevitt]

would it be possible to use the ami port to draw power?