An electrical system assembly for a motor vehicle may include a first electrical system and a second electrical system galvanically isolated from the first electrical system. The second electrical system may be switchable between an idle state and an active state. A capacitive coupling element may couple the first electrical system to the second electrical system. A signal transmission unit may be arranged in the first electrical system and may be configured to transmit an activation signal to the capacitive coupling element for activating the second electrical system. A signal receiving unit may be arranged in the second electrical system and be configured to receive the activation signal via the capacitive coupling element and switch the second electrical system from the idle state to the active state.