WARNING: This page is about a different car, the 2018 Kia Forte5 and 2018 Kia Forte. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Scantool Display - C_CAN Low & High Signal Waveform
Courtesy of KIA MOTORS AMERICA, INC.
Fig 2: Scantool Display - C_CAN Bus Voltage Level (High Speed CAN)