* ECM (Engine Control Module): This is the "brain" of the engine. It's a computer that receives information from various sensors (like oxygen sensor, crankshaft position sensor, etc.) and uses this information to control fuel injection, ignition timing, and other engine functions. It's usually located under the hood, often near the firewall.
* Ignition Switch: This is the mechanical switch that allows you to turn the key to start the engine. It's responsible for supplying power to the starter motor and other electrical systems when the key is turned. It's located in the steering column.
They are separate components with distinct functions. While a faulty ignition switch *could* prevent the engine from starting (thus appearing as an ECM problem), it's a problem with the power supply to the ECM, not the ECM itself.
