Patent attributes
A method diagnoses a no-start condition in a powertrain having an engine and a starter system operable for starting the engine. The starter system includes a battery, solenoid relay, starter solenoid, and starter motor. The method includes recording starter data over a calibrated sampling duration in response to a requested start event when the solenoid relay is enabled, including a cranking voltage and engine speed. If no battery current sensor is used, the method derives a resistance ratio using an open-circuit voltage and a minimum cranking voltage of the battery. When such a sensor is used, the method derives a battery and starter resistance. A fault mode of the starter system is then identified via a controller using the starter data and either the resistance ratio or the battery and starter resistances. A control action executes that corresponds to the identified fault mode.
