DISTRIBUTION AR 3646323 - Caterpillar

Data Link
A data link is used for the following items:
Communicate engine information.
Communicate with Caterpillar Electronic Technician (ET).
Calibrate the electronic engine control system.
Troubleshoot the electronic engine control system.
Program the electronic engine control system.The data link is used to communicate engine information to other electronic control systems. Also, the data link can interface with Cat ET.Cat ET can be used to program the customer specified parameters. The tool is plugged into the data link connector. This allows Cat ET to communicate with the ECM. Also, Cat ET can be used to display the real-time values of all the information that is available on the data link. This will help diagnose engine problems.Electronic Control Module (ECM)
Illustration 1 g01381771
Electronic Control Module (ECM)
The engine uses an ECM. The ECM is a microprocessor-based device. The ECM is mounted on the top of the front valve cover on the left side of the engine.The inputs and the outputs to the ECM are designed to withstand short circuits without damage to the control module. The electronic engine control system has the following features that are designed into the system.
Resistance to radio frequency
Resistance to electromagnetic interferenceThe system has passed tests for interference by two-way radios and by switching noise.The ECM power supply provides electrical power to all engine-mounted sensors and actuators. The following precautions have been designed into the ECM.
Reverse voltage polarity protection
Swings or surges of the voltage in the power system due to sudden alternator loadThe ECM also monitors all sensor inputs and the ECM provides the correct outputs in addition to acting as a power supply. Also, the ECM ensures the desired engine operation.The ECM is programmed with a selected factory engine rating. The ECM memory contains a personality module identification code. This code is used to avoid unauthorized tampering or switching of personality modules and other pertinent manufacturing information.The wiring harness provides communications to the following areas:
ECM
Various sensors
Data link connector
Engine connectorsThe ECM is programmed to perform the following functions:
Diagnostic tests on all inputs
Diagnostic tests on all outputs
Identify a faulty circuit.Once a fault is detected, the fault can be displayed on a diagnostic lamp. The diagnostic code can be read by using Cat ET. A multimeter can be used to check most problems. Also, a multimeter can be used to troubleshoot most problems. The ECM will record most diagnostic codes that are generated during engine operation. These logged codes or intermittent codes can be read by Cat ET.