DTC U0074-00: Can Communication: Module Communication Error (At-Bus)

System malfunction location	CAN communication: Module communication error (AT-bus)
Detection condition	TCM detects a CAN bus communication line (AT-bus) error. Precondition  Battery voltage is the standard or more.
Fail-safe	Not applicable
Possible cause	DTCs are stored in the following modules. PCM (See DTC TABLE [PCM (PYUL)] .) DTC TABLE [PCM (H3T)] (See DTC TABLE [PCM (H3T)] .) Selector lever (See DTC TABLE [ECL] .) Backup power supply unit (Without Mazda M Hybrid boost) (See DTC TABLE [BPS] .) Drive motor control module (With Mazda M Hybrid boost) (See DTC TABLE [SGC2/DMCM (WITH Mazda M Hybrid BOOST)] .) Mazda M Hybrid Boost battery (With Mazda M Hybrid boost) (See DTC TABLE [MHB (WITH Mazda M Hybrid BOOST)] .) TCM (except U0074:00) (See DTC TABLE .) Malfunction in wiring harness (including connector/terminal) between PCM and TCM (See CIRCUIT INSPECTION .) (See CONNECTOR INSPECTION .) Malfunction in wiring harness (including connector/terminal) between selector lever and TCM (See CIRCUIT INSPECTION .) (See CONNECTOR INSPECTION .) Malfunction in wiring harness (including connector/terminal) between backup power supply unit and TCM (See CIRCUIT INSPECTION .) (See CONNECTOR INSPECTION .) Malfunction in wiring harness (including connector/terminal) between drive motor control module and TCM (WITH M Hybrid BOOST) (See CIRCUIT INSPECTION .) (See CONNECTOR INSPECTION .) Malfunction in wiring harness (including connector/terminal) between Mazda M Hybrid Boost battery and TCM (WITH M Hybrid BOOST) (See CIRCUIT INSPECTION .) (See CONNECTOR INSPECTION .) Control valve body malfunction (TCM malfunction) (Refer to [CONTROL VALVE BODY REMOVAL/INSTALLATION ] in service information).
Repeatability verification procedure	Clear the DTC recorded in the memory. (See CLEARING DTC .) Perform the following procedure to ensure that the DTC has been resolved: Switch the ignition ON (engine off or on).
Courtesy of MAZDA MOTORS CORP.
1	TCM
2	PCM
3	Selector lever
4	Backup power supply unit (Without Mazda M Hybrid boost)
5	Drive motor control module (With Mazda M Hybrid boost)
6	Mazda M Hybrid Boost battery (With Mazda M Hybrid boost)