MP4.2+6.0

You will likely have a light on in the inst. panel too. It does this on mine any time I disconnect the battery. Clears by the time i drive it down the block. I think it probably clears if you just cut the steering wheel left and right too--it just needs to confirm it is getting good input from the sensor.

Not sure which other one you were referring to as new.

Common checks now on your core MMI issues would be to look for a broken optical connection or for a bad module among the ones on the optical loop. Search prior archives for more pointers (fortunately not one I have ever had to struggle with on my car).

MP4.2+6.0

It is a ring design type network, so one in, one out. Thus yes, you need a connector/coupling. Haven't had to deal w/ it personally, but I think they exist, including as a D3 part for early ones that may not have come with a sat module but had the optical loop for it.

JohnnyJ A6Q

this

ESICA14

Thanks Guys....

That tool makes sense as I'm starting to understand what I need to do.

Now I need to locate one :-)

And the ABS light is no longer an issue.

ESICA14

I just plugged in the used MMI control unit I purchased and SHE'S ON!

Thanks VERY MUCH to all who posted and helped me with this!!!!

For all who have a similar Optical Bus Diagnostic in the future, just replace that Control Module and move on (I hope)

I'll run it through its paces and get back with any questions.