This unit describes the performance outcomes required to diagnose and repair faults in the electrical systems of vehicles or machinery. These systems are single wire (non CAN-bus) networked circuits and include entry-exit locking systems, power windows, interior and exterior lighting, turning indicators, brake and hazard warning lights and electric drive motor circuits. It involves preparing for the task, selecting the correct diagnostic procedure, carrying out the diagnosis and the repair, performing post-repair testing, and completing workplace processes and documentation.