Pawel S

To confirm I understand it correctly - I should use the optical loop plug on main head unit, and then re-check all other modules?

storka

I think the genuine Audi are expensive and usually don't stock them.
Bmw and merc. Have the same.
I think someone bought from bow quite cheap.
I would find eBay seller in the states and buy.
Probably only need the one but who knows.
Unlikely two modules defective but?
If no luck testing what you have exposed others to look at later are phone module left floor and Bose amplifier.
Isolate all modules one at a time if no luck I would really swap out the Mmi head unit with a cheapy as last resort.
The loop will definately rule our defective modules one by one.
Good luck I know this a bit hit and miss and frustrating.
Been there done that !!
What would be more frustrating is getting charged hundreds by the garage and still not finding it.

Pawel S

Guys, I want to say I really appreciate your help and support. I am persistent and calm, would like to get to the root cause and replace the faulty hardware. If anyone of you ends up in Edmonton Canada, PM me, you have free beer during your stay.

storka

You cannot test the head unit with the loop I think.
Never tried though

ltooz_a6_a8_q7

The signal is weak. The head unit must be the originator.

Pawel S

What I am suspecting is the head unit failure as one of my issues. I am not seeing the LED blinking inside it.

Does anyone have diagram how Optical cables and modules are interconnected through the A8?

Thanks

ltooz_a6_a8_q7

Blinking inside the unit like my tv tuner. I'll see if elsawin has the diagram

ltooz_a6_a8_q7

Ok, I think I figured out how to test the modules. Plug everything except cd changer.
Unplugged cd changer, no led blinking on the unit. Press the CD button on the control panel, no led blinking.
Press TEL button, if the led on cd cable is blinking, tel module is good. Wait until the led is out.
Press NAV. If led is blinking, NAV is good. Repeat with Fm/am then all buttons.
To test the CD, plug in the Cd, unplug satellite, press the CD, check the blinking. No need loop test.
Confirmed, no led blinking inside unit, only cable.

storka

just buy a cheap head unit while you are shopping for the loop.
under $200 even cheaper if you are lucky.
with the loop and head unit it would eliminate every thing on the loop except for kinked optic cable, something between mmi head unit and console.
or something to do with the aftermarket setup
can anyone think of anything else.?

Pawel S

I will to the tests as per ltooz_a6_a8_q7 suggestion and report back tomorrow. I will get my hands on working head unit and get the loop testers as well. Thanks guys. Once this issue is resolved, I will consolidate all troubleshooting in one post for future forum members.