C 3500 HD Truck 2WD V8-8.1L VIN G (2002)
Information Bus: Description and Operation
General Description
CLASS 2 COMMUNICATIONS
The Class 2 serial data link allows modules to transmit, receive, or exchange data.
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The Electronic Brake Control Module (EBCM)
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The Powertrain Control Module (PCM)
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Vehicle Theft Deterrent (VTD)
CIRCUIT DESCRIPTION
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information
and commands are exchanged among the modules. In addition to this, Node Alive messages are transmitted by each module on the class 2 serial data
circuit about once every 2 seconds. When the module detects the class 2 serial data circuit shorted, the setting of all other class 2 serial communication
DTCs is inhibited and a U1300, U1301, or a U1305 DTC will set.
UART DATA LINE (UNIVERSAL ASYNCHRONOUS TRANSMITTER RECEIVER)
Circuit 799 exists pin 12 of the DLC, and is a dedicated communication link between the EBCM and the scan tool. When a communication failure
exists with the EBCM, this circuit should be checked. This UART circuit can exist alone, on in conjunction with class 2 serial data communication
information, depending on the vehicle, functions/RPOs.
