A communication line exists between the Engine Control Module(ECM/PCM) and the Transaxle Control Module(TCM). The communication is through a Control Area Network(CAN). Without CAN communication, an independent pin and wiring is needed to receive a sensor information from a ECM/PCM. The more information to be communicated, the more wirings is required. In case of CAN communication type, all the information need to be communicated among control modules such as ECM/PCM and ABS control module use CAN lines.

The ECM/PCM determines CAN communication error and sets DTC U0001 if communication with other control devices (e.g. ABS) via CAN is impossible or PCM detects that communication time via CAN exceeds threshold value.

Fig.1) Normal waveform with ignition ON