The M67 features two control unit (referred to as master and slave) that are interconnected by means of a ”private” CAN-bus. This private CAN bus connects not only the two DDE control units. It ensures the data exchange between the two DDE control units.
Similar to the DDW 5.0, the control units are equipped with module connectors. Both the hardware and the software of the master and slave are identical.
When the control units are fitted for the first time, a bridge in the wiring harness is used to specify which control unit works as master and which as slave. The bridge is located on the 58-pin connector for the slave between pin 38 and pin 51.
The software in each control unit saves in the EEPROM whether it is working as master or as slave. If the control units are confused after initial fitting, the stored master-slave identification prevents engine operation.
In this case, a fault is stored in the fault code memory and the control units have to be correctly connected.
The two control units also feature terminal resistors of 120 Ohm for the private CAN bus.
The private CAN bus is monitored in the same way as the PT CAN bus is monitored.