Understanding this XJ,MJ,CJ Jeep talk

So my mom give me my baby brothers Jeep has a couple electrical issues where where it has a parasitic draw or parasitic drain however you wanna call it so it’s an 8 of 88 so it should be an 89 Jeep Cherokee Pioneer I need to know whether I’m looking at CJ, XJ MJ whatever jeep J wiring diagram and most of them have the J this and I am not sure what that means but