By now, you may realise I don't fancy paying a lot of money to dealers, for things you can do yourself for next to nothing.
The much-discussed AUX cable is one of these! The Z4 Specific one is around £40 from a stealer, the E46 one that fits is cheaper, at around £25.
The MINI one also works, and I believe the price for this is still over £20.
Well, what this howto does is show how to create your own AUX cable, and install it, for a mere £5.84, in about 15 minutes!
Most of the information used to create this guide was taken from the official BMW installation instructions for the offical Z4 aux cable, however I had to work out the pin layouts myself, after searching google for hours without any luck.
Anyways - here we go:Requirements
1x BMW Z4 (any model)
2x Thin flathead screwdrivers (watchmakers / electricians / kitchen knife).
1x Medium sized Posidrive screwdriver
1x Soldering Iron
1x Length of Solder
1x Torch (it's hard to see the catches at the top of the vents!)
1x 6.5mm Drill bit
1x 3.5mm Stereo chassis socket - Maplin Part No: FK03D
1x 300kΩ 0.6W Resistor - Maplin Part No: M300K
2x 0.22uf Capacitors - Maplin Part No: WW56L
1x 10m Single-core wire - Maplin Part No: BL85G
1x 20m Insulation Tape - Maplin Part No: N07AN
1x Computer Connector Pins - Found in Maplins Computer connectors section
- £0.29Step 1This is the hardest step - Removing the blasted central vent! It took me the best part of ten minutes the first time to remove the ruddy thing, despite watching videos and reading loads of guides. I won't pretend it's easy, but trust me that these instructions ARE right, it's just that it's a right bugger!
To remove the vents, point the vertical vent slats on both sides at about 3/4 of the way down.
Looking into the vents, you should see two small, square holes in the top of the vent (one either side of the center bar), just behind the vents.I've circled them in this picture:
Inside each hole, there is a small metal tab, the top of which you can see in THIS picture:
Using one of the small flathead screwdrivers, carefully probe into one of the holes until the tip of the screwdriver catches the front of the metal tab. Once caught, pull the tab down and with the second screwdriver, gently prise it between the vent and the dashboard.
You should feel the vent move slightly forward.
Once it has, repeat the process on the other side (it's advisable to use the second screwdriver to "wedge" the side you've already freed.) and the vent should now wiggle free.It can be a little tight. I found tilting the front of the airvent unit upwards whilst pulling helped free it.Step 2
With the airvents removed (finally), you can set to removing the actual headunit.
Using the posidrive screwdriver, undo the two screws that hold the headunit in place.There is one plastic washer on each screw - be careful not to loose these behind the dash
Once the screws have been removed, simply pull the stereo forward carefully and you should be able to get it all the way out without disconnecting any of the connections.Step 3
Remove the plastic panel from the underside of the dashboard.
This can be done very easily by pushing it gently from within the dashboard, as shown in the following picture:Step 4
With the plastic trim removed, decide where you wish to mount the 3.5mm socket.
Mark it and then drill it at a medium-slow speed.Step 5
Now we have the stereo and panel ready, we need to construct our AUX cable.
Starting with the 3.5mm socket, we need to solder one wire onto each of the three connection points.
Looking at the socket, we'll number them as follows:
1: The brass coloured connector
2: The "loop" connector at the end of the socket.
3: The silver coloured connector
Wires #1 and #3 should be about 45cm long, wire #2 should be 1m long.
At the ends of wires #1 and #3, solder one of the capacitors. After each capacitor, solder the resistor so that it joins both capacitors.
Now, attach an additional 10cm of wire to the end of both wires #1 and #3.
Finally, attach one of the "computer pins" to the end of each of the three wires.
you should now have a cable circuit similar to this:Step 6
Wrap all the wiring with the insulating tape, ensuring there is no contact between any of the three wires with each other, or the metal framework behind the dash.Step 7
With the cable now constructed, feed it through the hole the headunit occupies, and down to the back of the framework, following the existing stereo wiring harness.
Then, via the bottom trim panel hole, find and feed the cable back through into the cockpit.Step 8
Attach the socket to the trim panel and then replace the trim panel in the dash.Step 9The final step before reassembly!
Looking at the rear of the stereo unit, you should see three seperate "plug sockets":
If you haven't removed the clip from the back of the stereo, you'll have a big, multi-wire plug connected to the top, larger, pins shown in the above.I thought the bottom left plug socket was for the CD changer, but I have a changer, and nothing plugged in here...
The plug we're interested in is the bottom right plug, as shown in this pic:
We now need to connect our AUX cable to three of the pins within this plug socket, namely pin numbers 4, 8 & 9.
Looking at the stereo in the same way as the image below, the pins we're interested are highlighted below:
RED PIN - #3
GREEN PIN - #4
BLUE PIN - #10
Refering back to the schematic we worked against earlier, we can see which wire needs to connect to which pin:Step 10
At this point, you should be able to turn the stereo on, and by pressing the "MODE" button a few times, find "AUX" now shows up on the list!
If it doesn't show, check that you've attached the AUX cable to the right pins (and that they've not fallen out - as this happened to me!)
Also, check that your soldering of the resistor and capacitors is still good.
If it all looks well, try removing the main wire harness from the stereo, so that is looses all power, then reconnect and see if it now shows.
If it shows up - all is well! If not, post and we'll take a look! Step 11
Carefully replace the stereo, making sure you don't accidently unplug any of the AUX cable pins from the back of the stereo.
It can be quite a pig to get the headunit back in and flat against the facia - if you're struggling, use the hole from the removed trim panel and fiddle with the stereo wiring harness until the stereo slides in fully.
Once it's in it's slot, screw it back in with the posidrive screws.Step 12
Final check! Before putting the vents back in, check that AUX still appears on the stereo.
You can also hook up your MP3 player to the 3.5mm socket and check you're getting audio.
If not, remove the stereo and check the pins are still plugged in - maneuvering the stereo has a good ability of unplugging them!Step 13
Replace the airvents by simply lining it up and pushing it in snuggly.Step 14
Replace the bottom trim panel.Step 15
head to the pub to spend the £15 you've saved
And that's it!
Theres a lot of instructions, but it really is a simple process.
Here's a pic of my "testbed" cable. It's the same circuit as shown in the above steps, but I used a bit of circuit board to allow me to try different caps and resistors without too much messing around:
If you have any questions, fire away.. or if you do this and it works, share your tale