Audio Systems: Car Radio Problem, chevy astro van, car stereo wiring

Question
I removed an FM Modulator from my car stereo wiring.  Since then when I turn my car off I lose all my presets and clock. Can help me out with what my problem is.  I have a 1992 Chevy Astro Van.  Thanks  

Answer
Andy,

 it sounds like a problem with the 12 volt constant i dont know how an FM modulator was in play to that but i would go back into my wiring make sure everything was tight and review my adapter harness's wiring .. but if you need the GM diagram i have it in PDF at
geocities.com/evilparadise02/stereo.html

hope this helps you out if you need anything else let me know

thanks