Modes of Operation
WARNING: This page is about a different car, the 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
During normal operation the ECM controls all of the ignition system functions. If the crankshaft position or either camshaft position sensor signals are lost, the engine will continue to run because the ECM will default to a limp home mode using the remaining sensor input. Each of the ignition coil/modules are internally protected against damage from excessive voltage. If one or more ignition coil/modules were to fail, a misfiring condition would result. Diagnostic trouble codes are available to accurately diagnose the ignition system with a scan tool.