ABS and BRAKE LIGHTS ON

I have read the previous posts about these lights, and all of them mentioned Service Engine Soon lights being on. This is not the case for me, all that is on is my (ABS) Anti-Lock light and my (!)(P) BRAKE lights. I drove my car during the day and these lights weren't on. When I went into my car the next morning they were on, it was parked with those lights not on. During this time, i had been messing around with the radio (installed new one) then switched it back to the stock one. I don't think these are related thought, just a note incase they are. Any help is greatly appreciated, thanks in advance.
-Trav

Best thing to do is get it scanned with a an ABS capable scanner that can read GM CHASSIS/ABS codes. You could have a serious fault with the ABS system and the code may help diagnose the problem. Also, check the master cylinder fluid level.

I don't think the radio and ABS problems are related.

I had already checked the fluid level (was hoping that was the cause) but its good and full, I'm going away for a week, and will have to get it checked when i get home. thanks for the input!
-tRAV