DTC U1255, Class 2 Initialization Error: Testing

Serial data DTC does not normally represent a failure within module. This is not true when there is an intermittent poor connection of class 2 data line to module. If DTC U1255 is history, check for DTCs in all modules connected to class 2 serial data line.
If DTC U1255 is current, clear DTCs. Cycle ignition. If DTC U1255 is still current, ensure all modules on class 2 serial data line are functioning properly. Check for short to ground or voltage in circuit No. 1807 (Purple wire) between BCM 24-pin connector C2 and other modules on class 2 serial data line. See appropriate wiring diagram in SYSTEM WIRING DIAGRAMS article. Repair as necessary. Recheck system operation.