Circuit/System Verification (Battery, Charging System And Starting System)

Ignition ON, verify that no crank relay, theft deterrent or automatic transmission DTCs are set that would cause the ECM not to enable engine starting.
- If DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
Ignition ON, observe the scan tool BCM Current Power Mode parameter. Place ignition switch in the crank position, the parameter should display Crank Request.
- If not the specified value, refer to Power Mode Mismatch .
Transmission range selector in park, verify the scan tool ECM PNP Switch and TCM Park/Neutral parameters display Park/Neutral.
- If the TCM parameter does not indicate Park/Neutral. Refer to Range Selector Displays Incorrect Range , for the 4L60/4L65/4L70-E transmission or Transmission Internal Mode Switch Logic for the 6L45/6L50/6L80/6L90 transmission.
- If the ECM Park/Neutral parameter does not indicate Park/Neutral. Refer to ECM Park Switch Circuit Malfunction.
Transmission range selector in park or neutral, attempt to start the vehicle. The crank relay should click and the engine should begin cranking.
- If the crank relay does not click or the engine does not crank, refer to Crank Relay Circuit Malfunction.
Ignition ON, observe the scan tool ECM Crankshaft Position Sensor Active Counter is not incrementing.
- If the Crankshaft Position Sensor Active Counter is incrementing, replace the Crankshaft Position Sensor.