Intermittent Dash warning lights

[PanelDeland]

Hey guys,got a weird problem going on.It's been about a year (5000-7000 miles) since new brakes.MC is full,E-brake works great.74,000 miles on truck.No engine problems or brake problems ever,only service on this truck has been oil changes,a battery and 2 sets of brake pads.It's a 2000 Blazer with 4.3,AOD and 2wd.We've had it since new.

Sometimes the ABS and brake warning lights are coming on.They always come on normal when starting and may go off normal or not.The brakes work good and the truck drives normal.They sometimes come on while driving(randomly) and may or may not go off.This has been going on for about 6 weeks and is driving me nuts.I've had the codes read and it came up with only a O2 sensor.Replacing that didn't solve the brake light thing but it took a couple days before it did it again.I can't find a blown fuse(i replaced to be sure),a pinched wire or anything else.I checked brake linings and they are good,no leaks I can see and i can all but lock them up.I did hit the anti locks a couple times in the snow about the time this problem started.

Any Ideas?

I need to figure this out since the QOV is starting to talk new ride and I don't want the payment to replace a perfectly good low milage truck that's paid for and reliable.