US Patent 7938096 Engine start control device and method

An engine start control device includes a starter energizing circuit that has two transistors connected in series and energizes a starter relay, and an idling stop ECU that performs energization control to turn on a transistor and energizes the starter relay when automatic start requirements are satisfied. Prior to the energization control, the idling stop ECU sequentially performs OFF failure detection and ON failure detection in one of the transistors, and OFF failure detection and ON failure detection in the other one of the transistors. The failure detection is aborted when failure is found. With this structure, ON failure in the two transistors can be detected with accuracy, and inadvertent driving of the starter can be prevented.