REPLACEMENT 9S3657 - Caterpillar

Illustration 1 g06144697
Electrical Schematic for the Data Links
The Transmission ECM will use two data link systems for communication between the other electronic control modules that are on the machine. Both data links allow communication with service tools.The data link is bidirectional. The Transmission ECM can send information and the Transmission ECM can receive information. The data link is not a visible component. The data link consists of internal ECM circuits, the related harness wiring, and the harness connectors.The Transmission ECM communicates over the two data link communication systems that are present on the machine. The two types of systems are listed below.Cat Data Link - The Cat Data Link is used to send system status information between control modules and the Caterpillar Electronic Technician (ET). All implement system diagnostic codes are activated using the Cat Data Link.SAE J1939 (CAN) Data Link - The SAE J1939 (CAN) Data Link is a high-speed data link system. The J1939 Data Link is used for high-speed system operation communication between the controls of the ECM and the control modules of other machine systems.In the event of a failure of the SAE J1939 Data Link system, the Cat Data Link is used as a backup system for operational communication.Data Link Diagnostics
Both of the data link systems on the machine are monitored by the Transmission ECM for abnormal internal or external circuit conditions. The ECM will activate diagnostic codes for a specific control module and the data link circuit when an abnormal condition is detected.When the Transmission ECM detects an abnormal condition in a data link circuit, the ECM will activate a "companion" diagnostic code along with the diagnostic code for the involved control module. This action will guide the technician to which data link system is involved.