Trailer Sway Control

Trailer sway is the undesirable yaw force a trailer can apply to the towing vehicle. Trailer sway control is a unique function of the vehicle dynamic system that uses steering wheel angle information from the SCCM  (vehicles with active park assist) or from the PSCM  (vehicles without active park assist) and the yaw information from the RCM to determine if a trailer sway event is taking place. If it is determined that an event is taking place, the ABS module modulates brake pressure to the appropriate brake caliper(s) by opening and closing the appropriate solenoid valves inside the HCU  while the hydraulic pump motor is activated. At the same time, the ABS module calculates how much engine torque reduction is required to eliminate the trailer sway and sends this torque reduction message to the PCM over the HS-CAN  . The ABS module also sends a trailer sway event message to the IPC  over the HS-CAN  . When the PCM receives the torque reduction message, it adjusts engine timing and decreases fuel injector pulses to reduce the engine torque to the requested level. When the IPC receives trailer sway event message, it flashes the sliding car icon and displays TRAILER SWAY, REDUCE SPEED in the message center.

Once the trailer sway has been corrected, the ABS module returns the solenoid valves in the HCU  to their normal position, deactivates the hydraulic pump motor and stops sending the trailer sway event and torque reduction messages. The PCM returns engine timing and fuel injectors to normal operation and the IPC  extinguishes the sliding car icon.

Trailer sway control only activates when vehicle speed is greater than 65 km/h (40.4 mph). Any malfunction that disables the RSC®  function of the vehicle dynamic system also disables trailer sway control. Trailer sway control can also be disabled by the driver through the menu in the message center. Regardless of the chosen state (enabled or disabled) set by the driver, trailer sway control is enabled at each ignition key cycle.