This vehicle does not use a 12V starter motor to crank the internal combustion engine (ICE). A much more powerful 300V motor generator located within the transmission is utilized to crank the engine. The 300V motor generator can rotate the engine to operating speed, 800 RPM, within just a few hundred milliseconds. The 300V motor generator allows near-instant starting of the engine.

The body control module (BCM) monitors the position of the ignition switch. When the ignition switch is placed in the Crank position, the BCM sends out a Crank-Request message over GMLAN. The hybrid powertrain control module (HPCM) responds to this GMLAN message by applying torque to drive motor generator 1 located within the transmission. Drive motor generator 1 is mechanically linked to the engine crankshaft.

The HPCM will not respond to the BCM Crank-Request GMLAN message if certain vehicle conditions exist such as the transmission gear selector position does not equal Park or Neutral or certain DTCs are set.

1. Ensure the range selector lever is in Park or Neutral.
2. Turn the ignition key to crank.
3. The engine should instantly crank and run.

⇒	If the engine starts and runs, the system is operating normally.

1. Verify no HPCM or engine control module (ECM) DTCs are set that would disable high voltage or that identify a gear selector switch concern.

⇒	If the specified DTCs are set, repair them first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle.

2. Observe the BECM Contactor System Status parameter. You should observe contactor status as Closed.

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If the parameter displays Precharge Inhibit, the BECM is operating in the precharge resistor protection mode and high voltage has been disabled for 35 minutes. Observe the BECM Precharge Wait Time parameter to determine the amount of disable time remaining. Turn the ignition OFF and wait the applicable amount of time before attempting to crank the engine.

3. Observe the HPCM IMS Range parameter display with a scan tool. The display should indicate Park or Neutral.

⇒	If the display does not indicate Park or Neutral, adjust the range selector lever cable. Refer to Range Selector Lever Cable Replacement.

4. Verify that serial data gateway module (SDGM) DTC B009F is not set.

⇒	If B009F is set, refer to DTC B009F.

5. Observe the SDGM Hybrid Crash Status parameter. If the vehicle has not been involved in a collision the parameter should display No Crash.

⇒	If the parameter displays Crash Detected and/or the vehicle has been involved in a collision the high voltage system should be inspected for damage before the high voltage system is re-enabled. Refer to High Voltage System Inspection.

6. Verify the vehicle has not been in a collision that resulted in supplemental inflatable restrain (SIR) deployment.

⇒	If SIR deployment has occurred the high voltage system should be inspected for damage before the high voltage system is re-enabled. Refer to High Voltage System Inspection.

7. Observe the BECM Hybrid Battery Pack Calculated voltage parameter with a scan tool. You should observe greater than 305 volts.

⇒	If the hybrid battery voltage is less than the specified value, attempt to charge the Hybrid Battery. Refer to Jump Assist.

8. Observe the BECM Hybrid Battery SOC parameter with a scan tool. You should observe greater than 20 % hybrid battery state of charge.

⇒	If the hybrid battery SOC is the same or less than the specified value, attempt to charge the Hybrid Battery. Refer to Jump Assist.

9. Turn the ignition to Crank. The engine should instantly start and run.

⇒	If the engine does not crank but audible transmission noise is observed while cranking, inspect the transmission for internal component failure. A seized engine or accessory drive could cause transmission damage during engine crank.

⇒	If the engine does not crank and no audible transmission noise is observed, continue with diagnosis.

10. Perform the HPCM scan tool Clear 300V Impact Detection DTC output control. Turn the ignition OFF for 60 seconds.
11. Turn the ignition to Crank. The engine should instantly start and run.

⇒	If the engine cranks, the DTC Information for SDGM DTC B009F had been previously cleared without performing the scan tool output control. Ensure DTC B009F runs and passes.

⇒	If the engine does not crank, continue with diagnosis.

12. Perform the HPCM scan tool Clear 300V Present DTC output control. Turn the ignition OFF for 5 minutes.
13. Turn the ignition to Crank. The engine should instantly start and run.

⇒	If the engine cranks, the DTC Information for DTC P0C76 had been previously cleared without performing the scan tool output control. Ensure DTC P0C76 runs and passes.

⇒	If the engine does not crank, replace the drive motor generator power inverter module (PIM).

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for PIM replacement, setup, and programming.