Modes of Operation
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.
During normal operation the engine control module (ECM) controls all ignition functions. If either the crankshaft position or camshaft position sensor signal is lost, the engine will continue to run because the ECM will default to a limp home mode using the remaining sensor input. Each coil is internally protected against damage from excessive voltage. If one or more coils were to fail in this manner, a misfiring condition would result. Diagnostic trouble codes are available to accurately diagnose the ignition system with a scan tool.