WARNING: This page is about a different car, the 2015 Kia Forte5, 2015 Kia Forte Koup, and 2015 Kia Forte. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: C-CAN Low & High Signal Waveform
Courtesy of KIA MOTORS AMERICA, INC.
Fig 2: C-CAN BUS Voltage Level Graph (High Speed CAN)