Engine Control Module
WARNING: This page is about a different car, the 2007 Saturn Ion Red Line, 2007 Saturn Ion 3, and 2007 Saturn Ion 2. However, it is still accessible from the selected car via links, so may be relevant.
The engine control module (ECM) contains the remainder of the logic of the theft deterrent system. If a class 2 message containing a valid password is received from the BCM, the ECM will allow starter engagement. If the ECM does not receive a class 2 message, or receives a class 2 message with an incorrect password, the engine will not crank.