As an instructor, I would see some techs in class cringe when they heard the words “voltage drop test” for testing poor starter circuit symptoms. It’s like I was shoving toothpicks up their fingernails! Funny thing is, once it’s understood, it’s used by every smart tech. It saves countless hours of trial and error and needless parts-swapping, and one Master Tech’s case (not me), 3 days of replacing batteries and starters and cleaning cable connections when it was just a bad ground cable internally. In fact, he even tested the battery cables off of the car with an ohm meter! Hmmm….!