System Operation: Start

When the BCM 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 also sends out the ignition mode message on the MS-CAN  and the HS-CAN  .

The ignition switch START circuit is also hard wired to the PCM. The PCM uses the ignition switch START input to determine when to activate the starter motor relay. REFER to STARTING SYSTEM - WITHOUT INTELLIGENT ACCESS (IA) .