u1000 class 2 serial communication problem

The class 2 serial data line on this vehicle is a star configuration, with the Body Control Module (BCM) and Powertrain Control Module ( PCM) each have a second class 2 serial data line between them. When more than one critical parameter does not have an identification number associated with it, the DTC will only be reported once. Cleared the code and drove the truck for a week. Most auto repairs shops charge between 75 and 150 per hour. Recently replaced 1/2 2/3 Shift Solenoid. The auto repair labor rates vary by location, your vehicle's make and model, and even your engine type. Google but there was no solution to the posters with the problem. No blown fuse, pulled them out to test and replace. The cost of diagnosing the U1000 GMC code is 1.0 hour of labor. next day I had my friend do a module scan on the truck, and there was a U1000 Code Class 2 Data Link Malfunction I have not a clue where to start looking for this malfunction. When a module does not associate an identification number with at least one critical parameter within 5 seconds of beginning serial data communication, Diagnostic Trouble Code (DTC) U1000 is set. Everything was working and I drove it home. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for State of Health monitoring. Operating information and commands are exchanged among the modules. Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. When a module does not associate an identification number with at least one critical parameter within 5 seconds of beginning serial data communication, Diagnostic Trouble Code (DTC) U1000 is set.

U1000 class 2 serial communication problem