A lot of anti-lock brake systems provide the power assist too. When the warning light is on, the computer has turned the system off. Given the recent battery replacement, the most likely suspect is a blown fuse. That often happens from the current surge when the battery is reconnected. Check the fuses first. If none are blown, you'll need a scanner that can access that computer to read the diagnostic fault code.
Wednesday, April 9th, 2014 AT 6:01 PM