The starter relay circuit sends a series of voltage signals to the starter so that it starts the engine and at the same time the vehicle can be started. In the starter relay circuit act several components such as the battery, the ignition switch, fuses, starter solenoids, as well as a series of sensors.
When the PCM (Powertrain Control Module) identifies faults in any of the ignition switch circuit components, the fault code P0615 OBD2 will be set. This kind of generic code is also often accompanied by other codes, which are set when a malfunction is detected in the ignition relay circuit.