Abstract: An automatic lighting system comprises a bypass circuit bypassing a manual lighting switch. During operation in an automatic lighting mode, headlamps and a clearance lamp of the automobile automatically turn on when the engine operation becomes stable upon completion of start-up operation. The stability in operation of the bypass circuit in the automatic lighting mode is increased by the provision of a delay circuit via which a voltage appearing at an alternator driven by the engine is applied to a base of a transistor that is used to close and open the bypass circuit. Closing a cranking motor switch to activate a cranking motor causes the bypass circuit to be inoperable so that the headlamps and clearance lamp will not turn on during engine cranking.