Rears break light doesn't turn on

@san38951 the very first thing you want to check all the fuses, the bulbs and the sockets for good connections. Next in line is your brake light switch. It is located under left side of dash, at the top of brake pedal. It's #3 in this image

Make sure that the plunger of the switch engages or disengage with the movement of the brake pedal. You can also use a multimeter or test light to see if the switch actually activates (closes contacts) when you depress the brake pedal. Because of the location of the switch it's a PITA to work on this but it is not to complicated. Of course, you always want to check all the fuses, the bulbs and the sockets for good connections.