No, sounds like you're set up like me. Yeah the GEN IV uses a amp probe and the BCM (indirectly through the ECM) controls the charge rate. Without the BCM it charges at a default rate I can't remember exactly what it was. It wasn't enough for my truck. I ended swapping the regulator on the Ad 244 160 amp Tahoe alt and using a smaller pulley. Mine is in a 1994 C1500 so clearance wasn't a restriction. A mail tune gets you running, dyno tune gets you close but data logging and tinkering gets you spot on.