I took my 2003 Blazer to the shop today because I needed a new O2 sensor, and had one, but could not get the old one off even with the special socket and a breaker bar and much inspired cussin'. In addition, both the ABS light and the brake warning light were lit. Actually, the yellow ABS light has been lit for so long I'm used to it, but that red brake warning light disturbed me. So they replaced the O2 sensor and the right front wheel speed sensor and said it is fixed. The red light went off but the yellow one stayed on. They said they couldn't get it to turn off and suggested I take it to the Chevy dealer and have them look at it. They charged me almost $500 for that little bit of work, so the dealer would probably eat me alive. On the way home I stopped on the side of the road, put the parking brake on and got out to look at something. When I got in and released the parking brake and took off I saw a brief red flash on the dash, then it was intermittent, and eventually stayed lit. It makes me think there's a loose contact somewhere. Parking brake switch maybe?

 

Does the extreme have a floor pedal parking brake? My 02 automatic does not have parking brake shoes. But I do engage the parking brake every night so in the morning when I start up my truck automatic headlight beams don't come on. Before I drive away I pull the release lever, and it always needs to be nudged with my foot while holding the release, otherwise the brake light remains lit.

 

Yes, it's a floor pedal brake. Thanks for the tip, I'll give it a try.
I was a bit doubtful when the guy told me the red brake warning light came on because the ABS light was on. I thought of those as separate-but-related systems, and besides, the ABS light has been on for a long time before the red light got lit. But he's a certified tech and I'm not, whaddo I know?