My Symphony HU had a couple columns of dead pixels since I bought the A6 early this year. The dash display also fails to display radio/CD info. I found a decent unit on eBay that came off an A4 and bought it. When I tried to swap the units today, the following happened:

1) The replacement unit did NOT ask for a security code.
2) It powers on but there's no sound output whatsoever. Rechecked connections, all are good. I did notice it didn't say BOSE at power up.
3) Placed original HU back, it also didn't ask for code. And it ALSO has no sound. I disconnected everything and reconnected and the sound came back but it STILL didn't ask for code.
4) I decided to give the "new" unit another shot. Same as before (no code, powers on but no sound).
5) I replaced the original HU back (again) but this time it refuses to power on at all. I checked the fuses and they're fine. Rechecked connections, all are good.
6) Through all of this, the dash display never did register the Symphony's activities.

My question is this: I don't have a VAG-COM (still looking around for a good deal since I'm cheap). Is there anything I can do to revive the radio without using the VAG-COM? If not, is there anyone in the central NJ area with a VAG-COM willing to lend me a hand? I've been beating my brains out for the past few hours over this (including STFA) and I'm losing my mind trying to find a solution. Also, any insight about the dash display? The pixels are working as the self-test indicates. TIA for any thoughts or suggestions. I'll xpost this in the audio forum.

 

The difference is that when it is coded for BOSE, the low level line out is turned on and the BOSE amp does the amplifying. If BOSE is turned off, the amplifying is done by the head unit.
As far as it not working at all, try again with the newer one you bought and see if it's dead. If it is, look for a wire that might have gotten pulled from the plug or is only hanging in the plastic casing of the wire (this is possible mostly with wires of 18 gauge or larger gauge... i.e. smaller size).
BTW, how hard is it to get the head unit out? gotta tie in my handsfree soon.

 

Ok this morning I tried a couple things. I took out the original HU and put in the "new" unit. It powers up (yay!) and still didn't ask for code and (why am I surprised) no sound. But at least it seems to be "working", LCD and all, just no sound. So I took THAT out and reinstalled the old unit. Viola! It's working again, bad pixels and all. I guess I'd have to bite the bullet and get the VAG-COM so I can recode the new unit. Meanwhile, anyone has any idea why my A6 doesn't seem to ask for radio codes? Throughout this little exercise I've removed and installed 2 HUs about a dozen times. <b>Not one time</b> has either radio asked for a code. Veerrrryy weird. But at least I can rock on!

BTW, odoboyusa, removing the HU is extremely simple. I got a set of radio keys from zdmak.com. All it took was to insert the keys properly and pull. Tricky part is getting the keys back out. You have to push the little clips in real good and wiggle the keys out. There're some awesome writeups by TeddyBGame, NSXJr, et al. that are essential resources. Oh, and thanks for your response. I feel better now that the new unit may not be a dud afterall and just needs recoding.

 

Audi replaced a Delta radio in my '91 100 under warranty. It was a remanufactured unit and had no security code and was just as bad as the one it replaced.

 

What year A4 was it?

 

It's from a 2001 A4. Haven't had time to do anything further with it yet.