Brake light and buzzer won't stop

When you apply the park brake, do you notice the intensity of the warning light change just slightly? It sounds like the park brake circuit is indicating that the brake is applied. This couldbe the result of a faulty switch, a short to ground in the circuit, or a faulty body control module. In the schematic, it looks like the switch closes, taking the signal to ground, when the park brake is set. If you can find the park brake switch, disconnect it first and see if the warning goes away. The switch has a single light blue wire going to it. That wire goes under the driver seat, and heads toward the front of the vehicle, passing through connector c200 in the left front of the passenger compartment, probably under the kick panel, or carpet. C200 is a 23 way flat connector, pin M is the park brake signal wire(light blue). If disconnecting the switch doesn't nix the warning, you may have to try removing the light blue at c200 pin M. If that stops the warning, it may be a short under the left front seat area. If it doesn't, move to the BCM. The light blue wire goes to connector C2 pin B2 at the BCM. Remove that wire and see if the warning still shows. You may need a BCM if it does. Itcould also have a problem with the park brake actuator, that is not properly activating the switch. You may be able to visually tell what the problem is when you get to the switch.

Any donation is fine. Did you check the brake fluid? Any applicable trouble codes?

Here is some audible warning info.
An audible warning is used to indicate a system fault or warn the driver of a critical vehicle condition. The radio is capable of supporting multiple types of chimes.

The actual generation of the pulse profile and sounding of the chime is performed by the radio. The BCM communicates chime ON/Off commands and rate information to the radio via class 2 serial data.

The radio supports chime functionality for each of the driver warning and status messages generated by the BCM. The BCM checks calibration data for chime information anytime a driver warning or message is displayed.

Audible warnings bring the driver's attention to one or more of the following conditions:

†The seat belt is unbuckled and the ignition switch is in ON or START.
†The key is in ignition switch, the ignition switch is set to OFF or ACC, and drivers front door is open.
†The headlamps or parklamps are on, the ignition switch is in OFF or ACC, the and drivers door is open.
†The parking brake is engaged.