The vehicle brake system consists of two hydraulic circuits. If one circuit is not working, the remaining circuit can still work to stop the vehicle. For normal braking performance, both circuits need to be working
If the warning light comes on, there is a brake problem. Have the brake system inspected right away.
Warning
The brake system might not be working properly if the brake system warning light is on. Driving with the brake system warning light on can lead to a crash. If the light is still on after the vehicle has been pulled off the road and carefully stopped, have the vehicle towed for service.

This light should come on briefly when the ignition is turned to ON. If it does not come on then, have it fixed so it will be ready to warn if there is a problem.
When the ignition is on, the brake system warning light will also come on when the parking brake is set. The light will stay on if the parking brake does not fully release. If it stays on after the parking brake is fully released, it means there is a brake problem.
If the light comes on while driving, carefully pull off the road and stop. The pedal may be harder to push or may go closer to the floor. It may take longer to stop. If the light is still on, have the vehicle towed for service. See Towing the Vehicle.
Service Vehicle Soon Light
Antilock Brake System (ABS) Warning LightParking Brake Indicator Switch Replacement
Removal Procedure
Remove the front floor console. Refer to
Front Floor Console Replacement.
Ensure that the park brake lever is in the fully released
position.
Disconnect the electrical connector from the park
brake warning indicator switch.
Remove the par ...
Hydraulic Brake System Bleeding (Manual)
Warning: Refer to Brake Fluid Irritant Warning.
Caution: Refer to Brake Fluid Effects on Paint and Electrical Components
Caution.
Caution: Only use products that comply with GM specifications and
check manufacturer information respectively. We recommend the use of GM genuine
...
Body Control System Description and Operation
The body control system consists of the body control module (BCM), communications,
and various input and outputs. Some inputs, outputs and messages require other modules
to interact with the BCM. The BCM also has discrete input and output terminals to
control the vehicle's body functions. ...