Wow. Phew. The radio works again, and I'm going to share my story to help any future readers.
The OEM setup:
2004 A4 cabriolet (3.0Q)
Symphony II radio 8E0 035 195Q
Antenna (aka Aerial) booster/switcher modules/boxes 8H0 035 225 B/D
I first notice the problem while driving, my reception comes and goes. Sometimes I notice it correlates to hitting a bump in the road, sometimes it doesn't. Eventually, it is entirely gone.
I research the problem online. I learn that the cabriolets have an issue where the wire breaks in the trunk/boot lid. The way to diagnose is to shake/manipulate the wires to see if the reception comes and goes. You can see someone doing it in the video here:
I shake/manipulate the wires, there is no change. I remove the trim/carpet from the trunk to investigate further. No matter what I do, I can't get the reception to come and go; it is only GONE. Examine the modules/boxes and their internals, they are fine, nothing out of place, no burn marks, no corrosion, no nothing. Check every connection, etc. After a few hours, I decide you know what, CDs are fine for now.
Time goes by, eventually its gets taken to a radio install shop to get fixed. After 8 days of communication, I've heard that its everything from them...need new modules, needs an aftermarket antenna, need the radio to be rebuilt. But they aren't sure enough of themselves to swallow the cost of the part if they are wrong. In the end, they give it back unfixed with the radio removed, but they are pretty sure it needs a new radio. I take their word for it.
I go to buy a new radio...I see that the model number I have is *different*. 8E0 035 195 Q
. Most are A
. I try to figure out if this is something different for the cabriolet. This is a big deal, because the A is readily available, and about $60. The Q, is nearly impossible to find, and goes for...wait for...about $700.
Well, I figure its worth the $60 to just try, and if it doesn't work, I'll just resell it for a small loss. Get the new radio in, install it...nothing. Unfortunately, I can't tell if its because its an A model or if its because the problem isn't in the radio.
I once again investigate the cables for a break. Strip it all down again, but this time I remove the rubber wire tunnel and I take the cloth tape off. I find a kink! Similar but not as pronounced as what is shown here: http://www.vwaudiforum.co.uk/forum/s...tion-on-A4-cab
I grab it right by the kink and try manipulating the wire to see if I get any reception. Nothing. I smush it together with all my might...nothing. Nothing. Not even a glimpse of reception.
I find this thread, and I see jonnies tip on diagnosing whether or not it is the booster. Essentially Take a thin piece of wire and touch it to the center conductor at the end of one of the cables. If it that thin piece of wire improves reception, it is the booster/module
I try this. My reception improves as he says; I determine that it must be a module because 1) I'm taking his advice and 2) I rationalize it cant be a break in the wire because the break is before the connector that I'm touching the wire to.
I discover that my modules 8H0 035 225 B/D are both hard to find, and expensive. I come across modules 8H0 035 225 J/P which look identical and I see written in another forum are the new versions of the B/D parts. I take the same leap of faith that I did on the radio and buy the different model number.
I install new modules. It works! For like a second. Then it doesn't work. I'm trying everything, combinations of modules, hooking some cables up and not.
At this point, I'm down to one thing only: repairing that kink. So I went for it. I strip the wire, hold it with my hands...and it works.
I finish up the job, tape the joint up nicely, re-thread the wire through the rubber tunnel (not easy) and get it all back together.
I try the combinations: Part numbers are compatible. All of my modules are fine, B/D/J/P whatever. The only thing that was ever broken was a tiny kink in the beige wire "ant"
If you have a cabriolet, repair any kink you see in coaxial cable. The problem may be so severe that manipulating the wire doesn't give you intermittent signal. Again, thoroughly investigate for kinks and repair all kinks before doing anything else.
Jonnies method for testing the booster for function is not correct. You will get an improvement in reception whether or not the booster is broken and therefore it is no way to determine if the booster is broken. Do not use this method to determine if your booster is broken.