Hy guys, I would respectfully suggest that if you have two good bright functioning brake lights, then you don't have a ground problem. When the turn signal switch is in the left turn position, and you step on the brakes, how many brake lights do you have? If you only have the right brake light, then the turn signal switch is separating the brake signal as it should. The problem seems to be in the turn signal switch. Turn signal switches are generally sealed units [not repairable]. There is a type of flasher unit that depends on load to make it flash, so if one of your turn signal bulbs is burnt out it will not flash, so check your front turn signal bulbs to make sure they are okay, hope that helps.
