My new (to me) 05 S2k does not play on the AM radio band. I noticed some threads about problems with not powering the amplified antenna when installing an aftermarket HU, but this is the stock radio and it's never been out of the car (it only has 6300 miles on it). I don't see a dedicated fuse for the antenna. Suggestions?

 

Do you have truly no AM reception, or very bad? Static, or silence? How's your FM reception?
You're correct, there is no fuse for the antenna amplifier, and that if it's not working you'll have
bad AM reception. Could be a loose connection, bad amplifier, or bad headunit. Best bet is to check
for power at the antenna amplifier with a multimeter.
Here's an old thread with some info.

 

FM reception and CD operation appear to be OK. If I turn up the volume on AM I get a gentle hiss but no sign of signal - even from local 760 WJR, a clear channel station. Thanks for the link. I'll pull the pins in the trunk and check for power to the antenna.

If it turns out that the HU is bad, I'll reference the old threads and replace it with one that streams BT from my iPhone.