Motorola T605 install in a 2006 Porsche Cayman S

This is another T605 I did in my personal car.  This time it is in my 2006 Porsche Cayman S with CDR24 head unit and Bose premium sound.  This car has a MOST fiber optic stereo network making it more expensive to get the Bluetooth stereo into the cars factory system.  Because of this I chose the FM modulator route but at least I used a wired in FM modulator which is less bad.  Here are the parts I used.

1. Audiovox FM100A FM modulator. Cost $41.98 on Amazon.
2. BT-BKR23M Bluetooth installation wiring harness from Discount Car Stereo. $19.98.
3. Metra 40 to standard antenna adapter set.  I bought this on eBay for $11.95.  I have found them even cheaper before.  Just search for "Metra 40 Radio Antenna Adapter Cable Kit".
4. And of course a Motorola T605 Car Kit.  You can get these on eBay, often as low as $25.

This video shows how to remove the head unit: http://www.youtube.com/watch?v=p0MdRdbmseY

Item 2 above is an adapter harness that plugs into the head unit to give power, ground, mute, and phone audio in to the T605.  This is handy because it uses the phone capability of the factory CDR24 head unit to support the phone hands free functions.  Even if the radio is OFF when a phone call comes in the radio will turn ON, show "PHONE" on the display, and use the factory speakers for the phone audio.  The adapter harness may require some modification, as it did in my case.  They supplied a green connector but my car has that connector slot already filled. I have to remove the 2 wires from the green connector and insert them into my existing connector.








This was a bit tricky if you don't have the connector tools.  I just cut the green connector housing and split it such that I could remove the terminals.  Be careful you don't damage the terminals.  Make sure you get them through the cover and blocker in the factory connector correctly before fully inserting them. You will find this information useful: http://www.pelicanparts.com/techarticles/Boxster_Tech/88-ELEC-Radio_Install/CDR_24_Pinout.pdf
Pay attention to the user settings to get the phone audio stream to work properly.  See the CDR24 manual for instructions on setting the user settings.

Initially I attempted to intercept the stereo signals inside the CD changer before the MOST module.  However, I could only find 1 circuit with audio.  I suspect it is multiplexed.  I also found at least 2 data links between the CD changed and the MOST module mounted on the back. 

You can buy MOST interface modules but they are crazy expensive.  I think the cheapest was $350 (http://www.installer.com/item/display_item.php?it=mostaux-por). Not really worth it.  Longer term I plan to get a double DIN head unit that supports Android Auto.  Those should be out next year and that looks like the way to go by far.  When I do that, I will need to replace the factory stereo amplifier too as it uses MOST.  That is a bummer since it has a great amp.

Here are some photos of the control pad.

It is in the visible area below the spoke of the steering wheel.  This location works best as the T605 lights can be a bit bright at night.  The control is easy to access too. I just used the double-sided foam tape to attach it.  I used rubbing alcohol to clean the surface first of course.  It does not stick real well but the tape is easy to change.

In order for the CDR24 to route the voice call sound through the cars speakers you must configure the telephone mute characteristics in the CDR24 menu.  Hold the [Menue] button until the display changes to "User 1".  Click (push in momentarily) the radio tuning knob (right knob) until you see "PH MUTE". Turn the tuning knob clockwise until the display says "AUDIO PH".  Click the tuning knob once more.  Wait a few seconds until the display returns to normal.  Now your Bluetooth system should use the stereo speakers properly.  See the CDR24 manual for more details.

Once the system is installed and the user setting configured to send the phone audio over the cars speakers, adjust the in-call volume. The following must all be done while the phone has an active call.  Use the T605 volume buttons while in a call to give the proper level to the CDR24 to prevent distortion (T605 volume not too high) and background noise (T605 volume not too low).  After you get that right, then adjust the CDR24 volume to the correct level. The CDR24 will remember the last used volume.

The system works very well.  For an FM modulator the stereo sound is at least decent.  It sounds as good as a local FM station. Unless you are an audiophile you will be content with it. Phone function is very good but the sound through the CDR24 phone audio stream (only used for phone calls and message reading) is a bit distorted.  I use my A2DP Volume app with all my cars to optimize the value of this system.

8/2018 update:  I recently replaced this and the CDR24 with an Android 8.0 head unit.