this page updated June 27, 2007
Running a cable to the trunk in a BMW Z3:
So what's the big deal about running a cable from the trunk of a Z3 roadster into the "cockpit" area to the radio?
All I could get from my ETK and TIS was this diagram (nothing in Bentley manual):

Not very helpful.
So I went to Daniels BMW and asked them to find the way before Z3 Fixit Day, so we could do the installs.

This is what Emmy's trunk looks like with the carpeting removed:

Driver's Side
Passenger Side
You can see the cable going into the CD Changer on the passenger side. This is where most connections take place, instead of at the radio in the cockpit, the other end of that cable. The battery cable also goes down the passenger side, so to avoid electrical interference that could make unpleasant noises Steve decides to use the driver's side - as BMW does with the radio- to route the cable to avoid interference from the battery cable on the passenger side. So... where's the opening on the cockpit side of that metal wall to get to the other side?
Somewhere under here:
Yes, that's right. That same area none of us can reach, behind the seats under the back window. It's where the top sits when it's down, and when it's up you can put stuff there, but not a nice place to have to do any work.
(Please click on the image to see a close up showing 3 plastic clips, p/n's 51168400262, 51168400261, 51168400252 in beige that are worn and good idea to replace)
So this is the opening in the trunk we want to use.
After about an hour Emmy's Roll Hoops are out
Dissassembling the Roll Hoops is not fun. I wouldn't try it. There are some instructions on Emmy's Fixit Page for anyone who wants to try it. Some people skip removing their roll hoops and just squeeze the wires through.
Take out the Seat Belt too.
And take out the storage bin/subwoofer trim as well
Aha- Steve has hit paydirt.A bundle of wires heading to a grommet.
Grommet from above
Grommet from below
light from above coming through the grommet hole
The passenger side still had to be dissassembled this far to get the storage unit/subwoofer trim out. Only then will the carpet release to reveal the grommet to the trunk.
This was just my experience, here are the words (and pictures) of wisdom from other Z3 owners who have found a way to route their wires from the cockpit to the trunk. DaveT did not have to take apart his roll hoops.
Dave T writes:

I routed wires between the center console to the trunk when hardwiring my iPod. Basically, you can remove the trunk liner and you'll find two cable access points between the trunk and the roof well - one on each side, in the corners. I used the one behind the driver's seat. You'll also need to lift portions of the carpeting in the roof well. This can be a little awkward for us big guys to move around in the cockpit. There is a rubber grommet between trunk and this area that can be removed to pass the wire thru. Once I had the wire into the well, I decided to take the wire along the edge of the well around to the area where the subwoofer is installed. Remove the subwoofer - top panel off and a couple of screws, if I recall correctly - and you can see an area where a cable will pass thru. I think that the wiring for the subwoofer takes this path, as well. Once you have the cable in the subwoofer area, pass it down to the area below where the sub sits. You can push the cable between the plastic (?) and carpet(?) into the area at the back of the center console. Most people have two blank knock out plates here. I used one for the alarm light. If you can, remove one of the knock out plates and use a piece of wire to help grab the cable and fish it through. Once the cable is in the area below the knock out plates, you should be able to fish it through to the center of the center console. From here, you should be able to follow the instruction we used for wiring the UNGO to get the cable to the front of the console or dash.
Here are a couple of pics showing the entry point in the trunk and the exit point on top:
In the trunk
by the roll hoop

Harvster writes:

Get an Alpine S620 from ebay for $100 and a Soundgate interface and plug into the preexisting wiring?. That hole does not go to the trunk. All wiring for stereo runs behind the drivers seat into the left trunk area. Since he has a storage compartment and no subwoofer, he can use the four subwoofer wires (see my subwoofer writeup) to do his hookups.

08-04-2002, 07:20 AM
hdd3md //m-powered Location: Chicago, IL 2001 M Rdstr writes:

You must take apart the center console and remove the roll hoops on either side, and take out the middle piece where the subwoofer sits. follow instructions on roll-hoop retrofit on then, push up on the bottow of the roof liner to separate it from the metal cage in the middle. Go to the trunk, and remove the back liner (grey) from the forward part of the trunk. on either side, are two grommets with lots of wires. i would feed all audio cables on the driver's side as the passenger side carries the (+) battery lead, and can induce noise.
From the cabin you can feed the wires directly through to the grommet hole (some 2-3 inch hole) on the driver's side....
I ran 3 pair micro XLN rca cables (monster cables), and have no noise. i also ran a 4 pair and 2 2-pair extra cables for upgrades in the future (to carry low-impedance electrical signals...)......
good luck

Scott Barton's cockpit to trunk
98 M Roadster Stereo System Upgrade
(aka Z3 Stereo Installation for Dummies)

TexZan (VA/DC) on 2004-02-13 at 23:04:43
a quick pointer to anyone installing an amp...After spending countless hours trying to find where the alternator whining was leaking into my new setup, it turns out it was the speaker wire, not the RCA cables (now for a return trip to Best Buy to return the shielded ones I bought that didn't work anyway). To finally solve the problem (without buying super-expensive speaker wires), I tapped into the factory amp wiring harness for any wires in the trunk, which was pretty-much rendered useless anyway by this point because I was using my Blaupunkt. If I needed anything run outside of the trunk, I would then switch to other cables. Not only did this solve the whine, I saved me trying to get cables through the grommet (which is a pain).(I wish I knew how he did this and wish we could have done this!)I then ran the RCA through a pre-existing hole in the left-side ceiling of the trunk (follow where the trunk interior light wires are) and out behind the factory amp. This ensured no interference from the power cables and a very clean look (even though the carpet covers it all anyway). Had I known that speaker cables would leak as much noise as these did, I would have used this setup the first time and saved many hours of hunting!

Zman's 1997 BMW Z3 1.9 liter

Alan's MZ3 Porting:

Rachel's Z3 97 2.8, driver's side front trunk-(original):

Rachel's Z3 97 2.8, driver's side rear trunk (original):

Rachel's Z3 97 2.8, passenger's side front trunk (original):

Rachel's Z3 97 2.8 Connector in the trunk (no idea what it's for)

fished wires through their cars since April 22, 2006

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