Modern BMW vehicles rely on multiple power distribution circuits and electronic control systems to deliver electrical power throughout the vehicle. Depending on the model, these systems may include junction box electronics, power distribution modules, relays, and electronically controlled power supplies. At Meister Werks, we use BMW ISTA diagnostic software, applicable wiring diagrams, and targeted electrical testing to evaluate power supply faults. Diagnosis may include checking fuses, voltage supply, ground connections, circuit integrity, and related control module communication. Our goal is to identify why a circuit or component has lost power rather than simply replacing fuses or expensive electronic modules.