i just bought a 2000 A4 1.8t and it has an aftermarket head unit in it. the radio gets really bad reception so i pulled out the head unit and found that the antenna wire had been cut in half and there was just a regular wire plugged into the antenna input on the head unit. so i tried splicing the antenna wire and plugging it into the antenna input and it helped quite a bit. so the radio reception during the day is ok, but still not very good as it is done pretty ghetto and i really need to get a new antenna wire from a junk yar. but my problem is this...whenever i turn the headlights on, the radio signal goes almost completely fuzzy. i found one other thread where a guy had this happen after having some aftermarket headlights installed. when i bought the car, the previous owner had bought some aftermarket headlights also, but replaced them back to the stock headlights for when i bought it. So is there a wire somewhere or a ground wire somewhere that i need to be checking that can affect my radio reception? i just dont see how my headlights being on have anything at all to do with radio reception. it does not affect the headu units function at all, just the reception. any inputs?

 

An after market head unit might need an antenna amplifier.

 

Or a noise filter on the power wire (not audio noise, but electrical noise) - talk to a stereo shop about it and see what they say. A noise filter might help you out. Some aftermarket head unit wiring come with one built-in. It's a little box on the constant power (yellow) wire. You should be able to pick one up at a stereo shop pretty cheaply (as in $6-7).

 

thanks, i'll look into an antenna booster and a noise filter. but i really dont understand what the headlights have anything to do with it though. i read in a post a long time ago that another guy had the same problem but never posted a cure for it. someone suggested it was a bad ground and that was it, nothing else was said. so i'm really curious as to what would cause this problem, but hopefully a signal booster will help and i wont notice it. thanks for the replies

 

I have the same problem, which I'm currently working to troubleshoot. When I got my A4 it wasn't bad, but it's gotten worse. Get this - when I turn on my headlights, the engine runs rougher. I definitely have a grounding issue somewhere. *sigh* Now I just have to find it.