SEAL-O-RING 2006410 - Caterpillar

System Operation Description:Use this procedure to troubleshoot suspect problems with the Cat Data Link.This procedure covers the following diagnostic codes:
254-9 Electronic Control Module : Abnormal Update Rate
590-9 Engine Control Module : Abnormal Update Rate
1042-9 ITSM : Abnormal Update Rate
1636-9 (Slave) Engine #2 Electronic Control Module : Abnormal Update RateThe Cat Data Link is used to share information between the following components:
Master Electronic Control Module (ECM)
Slave ECM
Integrated Temperature Sensing Module (ITSM)
Caterpillar Electronic Technician (ET)
Customer installed componentsThe 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 data link.The most likely cause of a diagnostic code for the 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 data link will not operate if the + wire and the - wire are interchanged in a connector.The data link can fail if a module is not receiving power. This can happen if there is a problem with the wiring that provides power to the module.The data link can fail if a module is programmed with the wrong flash file, or if a module has not been programmed with a flash file. Verify that all modules have been programmed with the proper flash file.Perform this procedure for all problems that are associated with the data link. If this procedure does not solve the problem, there may be a faulty ignition transformer. Refer to Troubleshooting, "Engine Cranks but Does Not Start".Harness CodesThe harness inside the terminal box has jumper wires (harness codes) for the slave ECM.The ECM that is connected to the jumper reads the harness code. This provides the ECM with a unique identifier on the Cat data link.The jumper wires must be connected in order for the Cat ET to communicate with the modules. The jumper wires must be connected in order for the engine to crank. The jumper wires must remain connected in order for the engine to run.The jumper wire for the slave ECM connects terminals P3-60 and P3-29.Check the continuity between the terminals. Verify that the jumper wires are in good condition. Make repairs, as needed.Note: If an open circuit is suspected in the circuit between the power supply and the powered component also inspect the power distribution box for the following conditions:
Abrasion of the insulation on the wiring within the box
Damage to the posts for the wiring to the circuit breakers
Damage to the internal parts of the circuit breakersThose conditions can contribute to the following difficulties with operation:
Unstable engine performance
Interruption of communication between the engine ECM, the fuel metering valve,