Module, Radio Frequency (RF Hub): Operation

WARNING: This page is about a different car, the 2021 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.

The Radio Frequency Hub (RF-Hub) is an integrated receiver (or base station) in the vehicle that communicates with other Electronic Control Units (ECUs) in the vehicle over either the Controller Area Network (CAN) data bus or a private serial bus to support the following standard and optional vehicle features or systems.

Keyless Go (KG) Ignition Systems - The Keyless Ignition Node (KIN) communicates with the Frequency Operated Button Integrated Key (FOBIK) through Low Frequency (LF) signals (125 KHz) then communicates it to RF-Hub through a private serial bus, then RF-Hub sends CAN data bus to the Body Control Module (BCM) for IGNITION status after valid key is verified. The RF-Hub also contains the controlling logic for the backlighting features.
Passive Entry (PE) - If the Smart door handles or exterior decklid release switch are activated, the RF-Hub signals and monitors the LF antennas. The LF antennas send out RF signals to the FOBIK to verify the FOBIK. When a valid FOBIK is recognized by the RF-Hub a CAN data bus message is sent to BCM to lock or unlock the vehicle by the RF-Hub
Remote Keyless Entry (RKE) - The RF-Hub receives and monitors RF signals from the RKE transmitter FOBIK; and relays the appropriate electronic messages BCM module over the CAN data bus to support the features of RKE functions.
Remote Start System - The RF-Hub receives and monitors RF signals received through the remote start antenna (longer range) from the RKE transmitter or the Passive Entry Keyless Go (PEKG) FOBIK; and relays the appropriate electronic messages to BCM over the CAN data bus to support all RKE functions including optional remote start function.
Secure Park Feature - Charger Pursuit vehicles also have a unique Secure Park feature that will prevent the transmission gear selector of a vehicle left idling from being shifted out of Park (P) or moving more than about 0.9 meters (3 feet) if there is no valid FOBIK detected within the interior of the vehicle. This feature can be enabled using a diagnostic scan tool. Once enabled, it is activated or deactivated by depressing the center remote radio button on the back of the steering wheel. While this feature is passive and does prevent vehicle theft, it actually relies primarily upon features of the KG portion of the PEKG system, which is discussed in further detail elsewhere within this service information.
Sentry Key Immobilizer System (SKIM) - RF-Hub uses a high security encryption system called "HITAG" for SKIM. The system marries FOBIKs, RF-Hub and the Powertrain Control Module (PCM) with unique secret keys for each vehicle. Swapping parts ARE NOT ALLOWED in the new system. Replacing any part of the system shall be done only in an authorized dealer using the proper diagnostic scan tool.
Vehicle Theft Alarm (VTA) System - The RF-Hub receives and monitors RF signals received from the RKE transmitter or the PEKG FOBIK; and relays the appropriate electronic messages to other ECUs in the vehicle over the CAN data bus to support the features of the optional VTA system.

The RF-Hub is connected to a fused B(+) circuit and has a path to a clean ground at all times. These connections allow it to remain functional regardless of the ignition status. Any input to the RF-Hub that controls a vehicle system function that does not require that the ignition status be ON such as depressing a button on an RKE or FOBIK transmitter, prompts the RF-Hub to wake up and transmit on the CAN data bus.

RF-Hub uses On-Board Diagnostics (OBD) to monitor all of the Functions and circuits it controls, then sets active and stored Diagnostic Trouble Codes (DTC) for any monitored function faults it detects. RF-Hub will also send electronic message requests to the Instrument Panel Cluster (IPC) through the BCM for the display of certain textual warning messages related to some detected functions conditions or faults.