LeSabre V6-3.8L VIN K (1996)
Serial Data: Component Tests and General Diagnostics
Circuit Operation
The serial data line is the means by which the microprocessor controlled modules in the vehicle communicate with each other. There are two different
serial data lines on this vehicle, Universal Asynchronous Receiver/Transmitter (UART) and Class 2.
UART Data Line
On UART based communication systems, there is a master of the serial data line and remote transceivers. The master controls the message traffic
on the serial data line by polling all of the remotes (control modules) and then waiting for the proper response. The control modules on the UART
data line are:
^
Electronic Brake (and Traction) Control Module (EBTCM)
^
Sensing and Diagnostic Module (SDM)
^
HVAC Programmer
Class 2 Data Line
Class 2 data is transmitted at a higher speed and messages are configured differently than UART data. While UART uses a master to control serial
data line traffic, Class 2 uses the peer-to-peer method along with message arbitration to manage data line traffic. The control modules on the Class
2 data line are:
^
Powertrain Control Module (PCM)
^
Remote Function Actuator (RFA) Module
