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SCION XB 2004 FM interference from rear defogger

A tree fell partially on my 2004 Scion XB last summer. Damage was the following: The rear passenger top corner was dented (dent size about 3" round); rear hatch door askew; and back window scratched a bit. Body shop repaired dent and door. When I picked up, FM radio had static when rear defogger put on. They claimed they have no idea the connection. If I use the rear defogger, instead of straight horizontal lines of ‘defogged’ areas I get circles. What’s going on? Thanking you in advance.

Sounds like the defogger wires and radio antenna are shorted together…

I think the defogger has some bad connections and this produces the uneven performance and the static due to arcing.

Does the SCION have a completely seperate FM antenna? I would like to look at the schematic of the FM antenna and look for signal boosters, BMW used them in quite a few different models.

I went and looked at the schematic and the SCION XB does use an antenna signal booster and has noise filters connected to the rear defrost grid. I would make sure all of this is still functioning as designed.

My take is that this happened when the body shop cut open the steel to repair that dent. What do you think?

What should be replaced to resolve this–the back windshield?

Do you think the body shop repair caused this?

I would try and match the location of the grid filters and the accident repair area and the antenna booster and the accident repair area. If they are close, it would be worth saying to the insurance company, “my radio has FM interference and right where they worked is the filter and the booster”.

Are they using the defrost grid as the antenna, this is a technique that does work very well.