The red warning light turns on for low fluid level, the parking brake isn't fully released, or there is an imbalance the two hydraulic systems, typically from a leak.
GM front-wheel drive cars also have a valve in the master cylinder that trips when there is a difference in fluid pressures. That valve will block fluid flow to one front wheel and the opposite rear one. Pedal bleeding and pushing the brake pedal more than half way to the floor will trip that valve. You may never know it's tripped until the pads wear out on one side and start grinding metal-on-metal and the other side looks like new yet.
Saturday, January 7th, 2012 AT 5:59 AM