Class 2 Communication Malfunction: Description

Modules connected by class 2 serial data circuit monitor communications during normal vehicle operation. Operating information and commands are exchanged between modules. When a module receives a message for a critical operating parameter, receiving module records identification number of sending module for state of health monitoring. Critical operating parameter, if not received, requires receiving module to use default values for that parameter. If a module does not associate an identification number with at least one critical parameter within 5 seconds of beginning serial data communication, DTC U1000 or U1255 will set, if DTCs U1300, U1301 or U1305 do not have current status and voltage supplied to module is in normal operating range (9-16 volts). Module will use a default value for missing parameter.