SCREW-MACHINE 3E8035 - Caterpillar

System Operation Description:The Cat Data Link is used to share information between the following components:
Control module for the Electronic Ignition System (EIS)
Electronic control module (ECM) for the air/fuel ratio control (if equipped)
Optional Generator Set Control (GSC) for the Electronic Modular Control Panel (EMCP II+)
Optional Customer Communication Module (CCM)
Customer installed components
Electronic service toolEach component communicates with the service tool via the Cat Data Link. The Cat Data Link consists of two wires that are twisted together. One wire is designated as "+". The other wire is designated as "-". The signals on the data link wires are a square wave type signal. The signals operate at a very high frequency. The signals cannot be measured with common service tools. Therefore, only continuity measurements can be made on the wires for the Cat Data Link.The most likely cause of a diagnostic code for the Cat Data Link are an open circuit or a short circuit. Connector terminals that are not fully seated in the connector body can create an open circuit condition. Be careful not to interchange the "+" wire and the "-" wire in a connector. The Cat Data Link will not operate if the "+" wire and the "-" wire are interchanged in a connector.The Cat Data Link can fail if a module is not receiving power. This action can happen if there is a problem with the wiring that provides power to the module.The Cat Data Link can fail if a module is programmed incorrectly. Verify that all modules have been programmed correctly.As you follow this procedure, refer to the schematic diagram that is appropriate for your engines configuration.Tandem Generator SetSome tandem generator sets are configured with a second Cat Data Link. The second data link is used to communicate the following engine operating conditions from the master ECM to the slave ECM:
Engine speed
Inlet manifold pressure
Throttle commandThe slave ECM uses this information in order to balance the load.If there is a problem with the data link, a 770-09 diagnostic code will be activated by the master ECM. The engine will shut down. If the engine is not running, the engine will not start.Diagnostics for the Digital Diagnostic Tool (DDT)The DDT provides indications for the following conditions: incompatible software, internal failures and programming errors. Troubleshooting steps for these faults are included in this procedure.
Illustration 1 g01042427
Schematic diagram of the Cat Data LinkThe engine is not equipped with a remote control panel.
Illustration 2 g01042420
Schematic diagram of the Cat Data LinkThe engine is equipped with a remote control panel that only includes a status control module.
Illustration 3 g03487096
Schematic diagram of the Cat Data LinkThe engine is equipped with a remote control panel that includes a status control module and air/fuel ratio control.
Illustration 4 g01042439
Schematic diagram of the Cat Data LinkThe engine is configured for Canadian Standards Association (CSA). The engine is equipped with an optional remote control panel with air/fuel ratio control.Test Step 1. Determine the Fault Code
Connect an electronic service tool to the service tool connector.
Look for the following diagnostic codes:
329-11 Communication Fault