DTC U1255: Generic Loss Of Serial Communications: Description
When ignition switch is in RUN position, all modules that communicate over the class 2 serial data bus send a State Of Health (SOH) message every 5 seconds to ensure system is operating properly.
DTC will not set if DTC B1982, B1983 or U1300 is current. DTC U1255 will set when Memory Seat Module (MSM) requests a message for initialization and the following criteria is met: Request is not acknowledged after all message retries are sent out, requested information contains an internal failsoft value, and the source ID with desired information is not known. DTC U1255 will clear when conditions for setting DTC no longer exists or upon every power mode initialization.
NOTE:
To identify circuit and components on class 2 serial data line, see appropriate wiring diagram under DATA LINK CONNECTORS in SYSTEM WIRING DIAGRAMS article.