2005 chev. malibu--push on brake, 1 brake light does not work. lamp is good

My guess is sig. light ( multifunction) switch. Brake light circuit passes through this switch after the brake light switch and before going to the brake lights. If the signal light works wires and grounds are good. Signal light will still work while the brake light does not! Body modules RARELY fail. Never replaced one and have been doing this stuff a hell of a long time!

Check the grounds, there are seperate ground in the circuit for the brake lights. It also has seperate circuits in the body control module.The body control module could have a fault in one circuit.