To this arm chair troubleshooter it's sounding more and more like the HU is the most likely cause. I think Chuck W. has the best plan.

 

As a potentially related question: Could one conclude from your research that a removed Fuse 38 would cause less drain on a "stored" car's battery?

 

Likely so (and probably worthwhile just to be safe), except as mentioned above if it is operating properly there should be little or no draw at rest.

 

You're right bud.

I decided to buy a new head unit (Alpine w/ ipod hookup installed in the glove bin)... sounds great, love the easier ipod control, and I have 0.00 amps being drawn at fuse 38 with car at rest.

Thanks to everyone for their input.

 

How cool is this thread, I have been having the same problem with my car, the "On" light on the radio never goes off and I wasn't sure what the problem was just knowing that my battery kept going dead (even bought a new battery). I'm going to try the fuse 38 pull out and see if that corrects; if so.. I'm off to get a new HU (the original stinks anywayz... )

Thank you posters!

 

Swapping radios is a good idea but I'd also just pull the existing head unit and check power availability at the plug on the swithched (+) line with the ignition off. It should be dead when the ignition is fully off - if it's not then your problem is upsteam from the headunit (likely ignition switch or fusebox).