why does the brake light go on. brakes done…fluid filled.
Parking brake (e-brake) partially engaged would turn the light on too. Did the light come on after you had a brake job done? If so I would take it back to the mechanic so they can double check and make sure something serious isn’t going wrong.
If the light is the B in parentheses as in…(B) this could mean that the brake fluid is still low.
There is a sensor in the fluid tank . Make sure it is plugged in. It may have gotten unplugged while you were working on it…
Check your brake pads also. A low fluid level can cause by worn pads.