Or any battery draw, disconnect the ground cable and connect a test lite to the cable and then the post. If there is any energy being used, the lite will turn on. If no energy being drawn the lite will not lite. If lite comes on, slowly remove the fuses slowly one by one. When the lite goes off the short or draw has been found. Care must be used as the interior lites and the clock will turn the lite on. When removing the fuses, remove fuse, check lite, then replace fuse. All circuits can be tested with this method.
Recently my truck kept drawing the battery down. After charging the battery back up to voltage, the test lite showed the back up lites switch was defective and would not turn off. frank

 

Or you can take the ground cable off and lightly rub it on and off the post and if you see small sparks you have a draw on the battery.

That is good info you gave. Thank You