Break Problems, ABS and Break Light

This is similar to the ABS, Break and Airbag light post.
Mine is a 1998 Sunfire Gt 120km and the ABS and regular break lights stay on, and yesterday the ETS light has also started to stay on. The breaks (front only) were replaced in like November (New pads, rotors, "break-wear adjustment" (the pads move inward to account for pad wear) was reset and break lines bled. And there have been no problems till earlier this week. The breaks seem to work fine but the ABS is disengaged. I've checked the break fluid and it seems fine, I've tried to disconnect the battery I only left it off for about 5sec (not sure if it needs longer to reset the chip. The weather has been cold (Guelph, Ont) and the car is always outside.
Any ideas, possible problems that it might be or suggestions?
Pretty much anything will help so thank you for any replies.

OK, a few possible problems:
1) it could be your wheel speed sensor
2) it could be a bad ABS wiring harness
3) possibly a weak battery
4) something else

I ran a search on this site and apparently the bad wiring harness is a somewhat common problem. However, as someone else mentioned, Autozone can check your computer codes which would help in the trouble shooting, and I believe they will do it for free. Generally that light goes on when the sensor senses that the pistons in your brake system are pushing the pads out as far as they can. Usually it just means that your pads are low or that you need more brake fluid. However, a faulty sensor, wiring harness, or anything else in the system could be causing it. I would get it checked out and find the error codes the computer is getting, then check in a manual to find out the problem. Good luck