System Operation

Conventional Ignition Switch - without Intelligent Access (IA)

System Operation

System Diagram





OFF

When the ignition switch is turned to the OFF position, the BCM (Body Control Module) sends an "engine off" message to the other modules over the HS-CAN (High Speed Controller Area Network).

Acc

When the BCM (Body Control Module) receives the ACC voltage input from the ignition switch it activates the RUN/ACC bus and the RUN/ACC relay, providing ignition accessory power to the various vehicle systems and modules. The BCM (Body Control Module) also sends out the ignition mode message on the MS-CAN (Medium Speed Controller Area Network) and the HS-CAN (High Speed Controller Area Network).

RUN

When the BCM (Body Control Module) receives the RUN voltage input from the ignition switch it activates the RUN/ACC bus, the RUN/START bus, the RUN/ACC relay and the RUN/START relay, providing ignition power to the various vehicle systems and modules. The BCM (Body Control Module) also sends out the ignition mode message on the MS-CAN (Medium Speed Controller Area Network) and the HS-CAN (High Speed Controller Area Network).

Start

When the BCM (Body Control Module) receives the START voltage input from the ignition switch it activates the RUN/START bus and the RUN/START relay, providing ignition power to the various vehicle systems and modules. The BCM (Body Control Module) also sends out the ignition mode message on the MS-CAN (Medium Speed Controller Area Network) and the HS-CAN (High Speed Controller Area Network).

The ignition switch START circuit is also hard wired to the PCM (Powertrain Control Module). The PCM (Powertrain Control Module) uses the ignition switch START input to determine when to activate the starter motor relay. REFER to Starting System .