The starter control system prevents the starter from accidentally activating when the shift position is not in P or N position/mode, or when the engine is running. If the vehicle is turned mistakenly while shift position is not in P or N position/mode or while the engine is running, the powertrain control module (PCM) will stop power to the starter cut relays. However, cranking to return from auto idle stop does not correspond to this (if equipped). In this system, two starter cut relays are connected in series (starter cut relay 1, starter cut relay 2) to prevent the starter from running continuously due to a starter cut relays malfunction. Also a diagnosis line (START DIAG) is connected to monitor the voltage between the starter cut relay 1 and starter cut relay 2. Based on the diagnosis line signals, the PCM detects an OPEN malfunction of diagnosis line, an ON malfunction of starter cut relay 1, and an ON malfunction of starter cut relay 2. The PCM also equips with return signal circuits of starter cut relay 1 and starter cut relay 2 to detect an OFF malfunction. If the STRLY1 return signal is HIGH for a specified time when the starter is ON (STS ON), the PCM detects a short to power of the STRLY1 line and stores a DTC.