-hef-

I am about 95% done with an amp/sub install. I am tapping into the trunk fuse panel to run a remote turn on lead. Every one of the fuses I have tested so far is constant 12V (hitch assembly fuses, rear defroster, right rear door controls, cigarette lighter, etc.). Without me testing every single one, are there any fuses back there that are switched or are they all constant?

-hef-

I wasn't able to get the amp to turn off when I killed the ignition using any of the fuses in the luggage compartment. So I tapped the cig lighter. Now the amp turns on and off as expected. Just an FYI to any other do it yourselfers putting in an amp.

oh and thanks to LASQ5 for the inspiration of doing the install in the 1st place.

Parsec

Looks like that is what AudiQ5Sleeper did too.
https://www.audiworld.com/forums/sho....php?t=2835659

Redd

If Audi would sell manuals everything needn't be pulling teeth.

"Every one of the fuses I have tested so far is constant 12V"
That only makes sense if Audi is doing things backwards, i.e. turning on devices by GROUNDING them instead of switching the +12V side.

Does anyone know, is that what Audi is actually doing? There are pros and cons of both ways, but switching the ground is, well, just not the way it is done in most of the world.

I was about to go looking for constant +12V to tap myself, I'm delighted that it is so easy to find, although not happy if that's how Audi is doing their power control.

LASQ5

Hey hef: I tapped mine off the cigarette accessory plug in the trunk too.. one thing I've noticed FYI: If you're listening to your music with the engine off, just turning on the radio with the MMI will not turn on your amp. Music will still play, just not thru the sub because it's switched by the cig acc. (I thought I had miswired something the first time this happened) To get the whole sound system to work with the engine off, you have to push the start button with your foot off the. That'll power up the ACC systems in the car as well as the MMI.
Upload some pics when you've got it all set up.

AudiQ5sleeper

yeah that. lol

-hef-

thanks. i would do pics if it would provide value to somebody on the board. i literally did the exact same thing as you with an Alpine amp (MRV-M250) and a cheaper 2 ohm model of the Kicker sub that you bought (10TCVT82). i even grounded to the same location, which brings me to a question...

i removed the battery strap down bolt, noticing the strap holder itself was painted black, so i put an unpainted washer between the ground wire and the strap down metal piece to avoid sparking. when i fired up the sub, i didnt see any sparking and the amp/sub worked fine. here is the weird part - when i open my hatch by pressing the release handle on the hatch, the sub vibrates/rumbles the whole time the hatch opens. when the hatch is fully opened, the sub stops making noise. so i turned the gain down on the sub, and the problem went away. turn gain up, problem back. is this a ground loop issue? here are all the details of my install:

- power straight to battery with inline fuse. the power cable is slightly longer than the ground cable.
- ground wire attached to body using battery strap down bolt just like LASQ5. no painted surfaces touching ground wire.
- remote turn on using 12v accessory power (cig lighter) in the trunk area.
- Alpine amp can accept a speaker level input, so I tapped into the wire running to the stock sub, and ran that to the Alpine. i dont think this can be the issue because i first noticed the problem when this wire wasnt plugged into the amp.

i have narrowed it down to the ground or the amp itself. thoughts?

-hef-

i cant say for sure, but what you are saying makes sense. i tested just about every fuse in there and the amp stayed on the entire time with the igntion off.

very easy. that right rear panel that has the cig lighter in it pops right off with 2 clips. pull the panel off, unplug the harness to the cig lighter to have some working room, tap in to the power wire, plug harness back in, snap the panel back in place, and you're done.

AudiQ5sleeper

usually bad ground will cause these issues

-hef-

thanks for the comment. here is the complete detail on my ground (from bottom to top layer):

at the bottom of the layer is the body of the car - unpainted
then the ground wire ring
then an unpainted crush washer
then the painted (black) battery tie-down bracket
then the top of the bolt holding the tie-down bracket in place - also unpainted

there shouldnt be anything touching paint. although i guess it is possible that if the washer is small enough, and part of the ring terminal on the ground wire bent up a little, it could be touching the painted bracket. i'd see sparking though, yeah?