Parasitic drains can be measured with ammeters with the battery cable. Now the problem with taking the battery cable off to install the ammeter is that, sometimes electronic modules are the source of the parasitic draw. In this technical tip clip instructor Dave Hobbs talks about some other tricks for diagnosing these problems. He talks about the class two message monitor– a feature available on the Tech Two and also the Master Tech– it basically tells which module’s active and which module is inactive. He also goes on to cover using a parasitic draw tool in order to not disrupt the circuit while using an ammeter. Watch this clip to learn how to use the class two message monitor and or a simple knife switch that can actually be used for some neat tricks in diagnosing some stubborn, hard to find, parasitic battery drains.