I was snooping around a D3 today.....and lucky me that the Satellite radio was not installed.

Looking in the trunk I found the connectors, you just get the new module, plug the power connector in (which also includes the diagnostic wire), plug the two antenna wires in, and take the jumper off the MOST (fiber optic) connection.

Because the Satellite unit is not installed, and the MOST network is a ring, you need to put a jumper in. It takes light from the "goes in", runs it around in a circle and sends it out the "goes out".

If you look at the control module under the Nav disc unit, you can see the MOST wires plug in. The "goes in" shines a light on a photoelectric cell, the module converts it to a digital signal (actually, the light is a digital signal, it just converts it to a useful electrical signal), then it adds what it needs to the signal, the signal is then passed on (with any additional commands or responses from the unit) via a LED that blinks and lights up the "goes out".....off to the next component it goes.

If you have less than a 1" minimum bend radius, the light reflects back the cable, not down the cable.....so the signal is lost. The inside of the cable is clear and has a reflective covering all around it to reflect the light down the cable.

<img src="http://www.audipages.com/images/most2.JPG">

<img src="http://www.audipages.com/images/most1.JPG">

 

Except this time with light.

 

Try checking with your dealer and see if you can speak with a few A8/A6 techs. Guys where just throwing them away until they informed us of its diagnostic uses. Not that I see many MOST-ring problems.

 

...price @ Audi dealer is about $29.