I have a cobra-gt model 7510 auto analyzer. it has 3 connections. one red, one black, and one that has a plate on it that has spots on each end that look like you would bolt it to a stud ..
because it doesn't have its own battery source, I would assume, red and black to battery of vehicle and third connection to negative side of coil....

before I hook it up and fry it. I would like to know for sure.... thanks steve