The data link is an input and an output of the ECM. The data link is designed to communicate with other electronic control modules through the machine harness. The data link is not a visible component. The data link consists of internal ECM circuits and the connecting harness wiring. The data link is bidirectional. The data link allows the ECM to receive information and the data link allows the ECM to send information.
Caterpillar Electronic Technician (ET) also communicates with other ECM modules through the data link. The ET will list the other ECM modules and the available diagnostic information.
Note: All electronic control modules (ECM) that use the data link have a module identifier (MID). The MID is listed for each module:
Machine ECM ... 039
Engine ECM ... 036
The CAN Data Link is used in order to aid the machine ECM with the control of the transmission.