Circuit/System Description

WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

When the ignition switch is placed in the START position, a discrete signal is supplied to the body control module (BCM) notifying it that the ignition is in the START position. The BCM then sends a serial data message to the engine control module (ECM) that crank has been requested. The ECM monitors the park/neutral position switch, or the clutch pedal position sensor. If the transmission is in Park or Neutral, or the clutch is pressed, and there are no DTCs that inhibit engine starting, then the ECM supplies voltage to the control circuit of the CRNK relay. When this occurs, battery voltage is supplied through the CRNK relay to terminal A X1 of the starter solenoid. The starter solenoid energizes, and supplies battery voltage to the starter from the ring terminal X2 to crank the engine.