Off and on for the last year or so my ABS and Parking Brake lights have come on in my truck (2000 S-10 pickup). During the summer I was also getting a scraping noise from the front right wheel. These things led me to believe that an ABS sensor in the failing wheel hub had gone bad. I ended up replacing both front wheel hubs (bought on Amazon for about 1/6 the price the dealer wanted) but the issue persisted. Also, the lights were not permanently on, sometimes I'd do a long drive without issue, sometimes they'd be on before the truck was even started. Turns out there's a relatively easy fix, I did it this week and have not yet had the lights come on (which is good, when the ABS lights are on the Anti-Lock Brakes are disabled and there's a bit of snow and ice on the ground now.)

The fix with photos is here: ABS module/Light Fix with pics, and a video on the removal and fix of the ABS module is here: Chevy ABS and Brake Dash Light fix. If you aren't comfortable doing this yourself, Module Master would be happy to do it for you, provided you have the right ABS module. All in all for a couple bucks worth of RTV silicone and less than an hour of my time I saved myself the $900 the dealership wanted to fix this...