Electrical System Flunked

Not much to add here but maybe a couple things will help.
The brakes lights are on a seperate circuit than the turn signals. Brake lights get power whether or not the key is turned on. Turn signal is powered from the accessory feed - which requres key in run or accessory.
"Accessory" is anything not critical to running the engine.
Hazzards were powered different ways in different years. Regardless, the switch gets power at all times including with key off.

A meter like Halifaxhops posted indicates current flowing in or out of the battery.
It is not sensitive enough to show very small drains, but if it shows discharge with the key off, that's a clue where to start tracking down the problem.
If it shows discharge with the engine running, then that indicates the alternator is not providing enough power to recharge the battery. It should show charging after startup, and once that is done should show no current flow.
Current to added electric devices between the battery and the meter will not show as discharge on the meter. As 67Dart273 wrote, you must check that.