Theory Of Operation

For the engine to start, the Sentry Key Immobilizer (SKIM) feature of the Radio Frequency Hub (RF Hub) and the Powertrain Control Module (PCM) must successfully communicate data over the data bus. Once the RF Hub sends the message that a valid Frequency Operated Button with Integrated Key (FOBIK) is being used, the PCM and RF Hub perform a "handshake" routine, encrypted with the VIN, to validate this information, and a match allows the engine to run when the ignition state transitions to Start or a remote start occurrence. The repair of this fault is determined by the ability of the RF Hub and PCM to complete a successful handshake routine over the bus.