Door Lock Serial Data Line
The door lock serial data line does not communicate with the scan tool via the DLC. Door lock serial data information is interpreted by the Driver Door Module (DDM) and transmitted on the Class 2 data link by the DDM.The door lock serial data line is used for serial data communication between the door modules as well as the window switch - driver.
In order to diagnose the door lock serial data line, refer to A Diagnostic System Check - Door Systems in Doors. Diagnostic System Check - Door Systems