Can scanning device of ECU used for diagnose current draw problem in car?

Answer 1

the ecu is only capable of monitoring systems that it is set up for. amperage is really what the computer is looking at, nor does it like any situations dealing with amperage at the level that the alternator is capable of developing. the scanning device that you mentioned before can only show you information that the ecu has so, no the scanner will not allow you to look for a current draw issue. a good old fashioned multi meter is all you should need.

Answer 2

If you mean running the battery down while the car is not running, the answer is no, it can not diagnose that.