Diagnostic system and method for vehicle starter

A diagnostic system for a vehicle with an internal combustion engine and a starter-based stop-start system comprising:

• an electronic control unit configured to control the operation of the stop-start system;
• a starter having an electric motor drivingly coupled with a shaft assembly;
• a first gear mounted on the shaft assembly;
• a solenoid operably coupled with the shaft assembly wherein operation of the solenoid shifts the first gear into and out of engagement with a second gear, the second gear being coupled with the engine and wherein the engine is startable by rotating the second gear with the first gear;
• a sensor operably coupled with the shaft assembly for detecting rotational movement of the shaft assembly in a first position wherein the first gear is disengaged from the second gear;
• the electronic control unit being operably coupled with the starter motor, the solenoid and the sensor, wherein the electronic control unit performs at least one of a first diagnostic check and a second diagnostic check before stopping the engine as a function of the stop-start system wherein:
• in the first diagnostic check the electronic control unit energizes the starter motor with the first gear disengaged from the second gear and then, with the shaft assembly in the first position, uses the sensor to determine if the shaft assembly is rotating wherein a rotating shaft assembly indicates that the starter motor is operable and a non-rotating shaft assembly indicates a starter motor failure;
• and
• in the second diagnostic check, the electronic control unit detects the rotational speed of the shaft assembly with the sensor while the shaft assembly is in the first position and the shaft assembly is rotating, the electronic control unit then energizes the solenoid to move the shaft assembly out of the first position to a second position where the sensor cannot detect rotation of the shaft assembly and then analyzes the signals provided by the sensor after energizing the solenoid wherein sensor signals representing no detected rotation of the shaft assembly after energizing the solenoid to move the shaft assembly to the second position indicates that the solenoid is operable and sensor signals representing a non-zero rotational speed of the shaft assembly after energizing the solenoid to move the shaft assembly to the second position indicates a solenoid failure due to the solenoid failing to move the shaft assembly out of the first position;
• and
• wherein, if a starter motor failure or a solenoid failure is detected when conducting the at least one of the first and second diagnostic checks, the electronic control unit suspends operation of the stop-start system.