Circuit Description

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation when operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. When a module does not associate an identification number with at least 1 critical parameter within about 5 seconds of beginning serial data communication, DTC U1000 or U1255 is set. The DTC will only be reported once if more than 1 critical parameter does not have a sending module identification number associated with it.

The following systems communicate on the class 2 serial data circuit:

• Body Control Module (BCM)
• Electronic Brake Control Module (EBCM)
• Electronic Suspension Control (ESC) Module
• HVAC (with CJ2)
• Sensing and Diagnostic Module (SDM)
• Instrument Panel Cluster (IPC)
• Driver Door Module (DDM)
• Passenger Door Module (PDM)
• Seat Control Module (SCM) (with AAB)
• Powertrain Control Module (PCM)
• Radio
• Remote Control Door Lock Receiver (RCDLR)