I'm not positive, but I suspect the rear defroster grid does double duty as the antenna. I think that because my 2001's reception gets much worse if the rear defroster is on. See if the rear defroster fuse popped due to the leak.

 

Is there a fix for the rear window defroster interference with the radio when on? Drives me crazy. Everytime I turn on the defroster the radio cuts out or the signal is terrible .

 

I looked at the wiring diagram for the radio circuit on BBB industries web site. I didn't see any inline noise suppression, so it is probably integrated into the radio itself. Either replace the radio or live with it. Try a salvage yard radio. My old Navigator had a bad radio when I got it and I found an OEM Alpine unit for $20 at Pull A Part that worked great. Pulliing the radio isn't hard. See video.

 

I recently purchased a 2001 Avalon XLS with antenna problems, and traced the problem to a replacement rear windshield that has the defrost circuit (which works perfectly), but no built-in antenna at all. I still get lots of FM stations, but the JBL system only sounds great when I'm in the heart of a major city. My guess is that your antenna is completely disconnected at the head unit, or shorted out to ground. The antenna in our car runs along the transmission tunnel to under the rear seat, and from there to the passenger side rear pillar and terminate in boxes of unknown function right next to the windscreen. I believe the factory antenna is active with a tuned amplifier designed for the wire mesh on the rear windshield.

I would like to install a shark-fin type antenna on the roof above the rear windshield, but the connections are not plug and play. If anyone has any idea of how to mod the existing antenna wiring, I would love to hear it.

 

Just wanted to thank Bigplanz the video helped a lot I had checked all all the fuses in and out of my Avalon they where all good went to bone yard found a JBL stereo system in same year Avalon 1999 took me 5 mins to pull out went home pulled out stereo in my Avalon got FM reception right out of the gate am and cassette work great also all controls work well it had my saved stations locked in all ac controls work great went to play a CD could not put one in found 3 cds stuck in there got them all out yet it will not take a CD in so how hard is it to put in a CD player/ bluetooth in and disconnect the CD player in there now?any thanks so much Bigplanz