Installation of Amplified Subwoofer in a 97 A4 with Delta/Bose (Bazooka/Kenwood/or Collins tube style sub or any amplified sub with speaker-level inputs). Note: this will also work for installing a mono-channel sub amp.

Very simple installation, with the hardest part of the install being the running of the power lead from the engine bay to the trunk. You can save up to $100 by doing it yourself, it takes about 2 hrs to complete(leisurely pace). This install is for a powered sub that uses speaker-level connections, but an RCA version of this install can be done by following the FAQ written by David Pincus, whom I thank for his advice.

Also, keep in mind that this install works for a 97 A4 with Delta/Bose system, it may work on others but I take no responsibility and make no claims...

Tools that will be needed:
-1/4" drive ratchet(optional)
-3/8" drive ratchet
-8mm long and short socket
-8mm wrench -the smaller the size the better
-17mm socket or wrench
-Wire strippers and crimpers-the sharper the better
-Electrical tape for insulating connections
-Phillips screwdrivers
-Flat tip screwdrivers-small and medium in size
-Stretched-out wire clothes hanger
-Patience

Supplies Needed:
-8gauge wire for you POWER lead-about 20 ft (preferably red in color)
-Fuseable link with 30AMP fuse, can be cut and crimped to any length on the power cable.
-Some SPEAKER wire-14gauge-about 15 ft per side (left/right speaker)
-Wire for your GROUND, should be the same gauge as POWER wire(preferably black in color)
-Wire for your REMOTE TURN-ON, 15 ft (preferably blue in color)
-Some FEMALE SPADE connectors, these will replace the ones for your rear speakers. I used 4.
-Some wire joiners-BLUE in color, these are the middle of the 3 sizes...
-Round connectors for the battery and ground(ground should have 1/2" hole).
-Shrinking tube is an option for the splices, but electrical tape will work just fine...

Here we go:

First step will be to install the power lead from the engine bay; this step will take the longest. The wire will need to be at least a 10gauge wire, preferably an 8g or 6g. Use a fuseable link between the sub and battery. I used a 30 amp fuse on the recommendation of my local shop.

Take a look at the FAQ on removing the ECU box to familiarize yourself with the area, the illustration there will make things very clear. There's no need to disconnect the module just move it out of the way to expose the opening into the firewall. We'll begin by removing the cover of the ECU box. Locate all five screws, the fifth will be at the back of the box. To get to this screw, get in the cabin, turn your key to the on position, turn your wipers on and when the driver side wiper is at the 12 o'clock position turn the key off. This procedure will get the wiper arm out of the way. You should be able to see the screw now, you can move the plastic trim up a little bit to get a ratchet or wrench back there. If you have a 1/4 drive ratchet use this and a small 8mm socket to remove it.

Once you have removed the cover from the ECU box, remove the ECU module by using a flat tip screw driver and pushing the clips on the sides gently OUTWARD/UPWARD. Move the ECU out of the way so the hole can be exposed.

Now, go back to the cabin. Remove the fuse panel cover, this will give a straight line from the inside of the car to the hole in the ECU box. Remove the trim panel next to the hood release lever, 2 Phillips screws, one above and one below, remove the small cover with a flat head screw driver.

Once the the panel is off, from the fuse box side, you'll be able to see light from the ECU hole...take your POWER cable, with some electrical tape attach it to a straight end of the clothes hanger and feed it to the hole. Pull out enough length to reach the battery. Remove the Negative battery terminal before connecting anything. Keep in mind that you may have to re-enter the code for your stereo and reprogram the one touch window up/down feature. Make a small (1/4") V shape cut on the top of the box for the new wire to run through. Put the lid back on the box in the reverse order of removal.

You can try to add the power lead to the battery by removing the nut from battery terminal, attaching the new connection and re-attaching the nut. You can do this at your own risk!!!! Do not let the battery terminal come out of the post. Don't try to attach it to the 4g cable on top of the battery connector use the nut instead, it's easier to keep everything connected..

Run the newly installed cable under the plastic trim, just pull it out a bit in tuck it under, you'll need to remove the rear seat, it just pops up...Once the rear seat is out, fold down the backrest you can run the power wire all the way to the trunk under the folded backrest. You'll see what I mean, this is very clean.

Remember you FUSEABLE LINK, it can the added at the battery or in the trunk, but it must be installed. I chose to do mine 3/4 or the way to the trunk, it is hidden under the seat.

Next it's the splicing...get in your trunk, on your back, and look at the rear speaker, if you have the stock Bose subs remove the plastic cover, you'll see the black/white(+) and the all black wire. We'll be tapping the blk/wht(+) wire on both sides. You have a choice here, clip the spade connector, twist the new wire along with the old and crimp a new spade on, or simply strip a piece of shielding and wrap the new wire around it. I went for the former, it's cleaner. After the splicing is done, you can run wires thru the round openings at the very back of the rear deck. very stealthy place.

Note: If you want at a later time add a mono-channel amp instead of your amplified tube, tap into both + and - speaker wires just in case you amp requires it, mostly you'll be using the + 's.

Once your rear speakers are tapped, we'll tap into the Bose amps power cable. Remove the wiring connector, the connector has only one clip, once undone pull it back and to the left. There are 2 solid white wires, you want to tap into the THICKER one, should be below a 10g red/blue wire. CAREFUL not to cut, just strip enough to splice your REMOTE TURN-ON wire.

Next will be the GROUND, locate the hooks for the cargo net, I used the one closest to the driver side rear seat. Under the carpet you'll see the mounting bolt. Using a 17mm socket or wrench, remove this bolt and connect your ground here; a 1/2" round spade? will do perfectly.

You now have all you connections, connect them to your new toy and enjoy...I used some 3/8 flexible wire manager tubing to put all the wires together. Leave yourself enough length to move the subwoofer around to various parts of the trunk until you find your ideal spot.