Ignition Switch: Description: Switch-Ignition

The electronic ignition switch (EIS) is located on the instrument panel. It is the main on/off switching device for the vehicle starting, ignition and electrical system. The EIS is an electronic module that communicates with other vehicle modules through the CAN-C bus. The EIS does not function like a standard ignition switch, as is not directly in line as a switch to control battery voltage when the ignition is in the ON, START, or RUN positions. Instead, the EIS enables the gas Powertrain Control Module (PCM) or diesel Engine Control Module (ECM) to actuate the ignition run, and start circuits depending on the position of the EIS key. If installing a new EIS, a scan tool must be used to flash the new EIS with the current vehicle configuration.