Working on BISG/MGU Hybrid Starter-Generators: A Tech’s Field Guide to eTorque, PowerBoost, and Belt-Alternator-Starter Systems

Belt-integrated starter-generators are showing up on more trucks and mild hybrids, and they’re nothing like the alternators techs grew up with. Here’s a practical rundown of what these units do, how to diagnose them, and where the real time sinks are hiding — especially that belt tensioner.