DTC U1255: General Loss Of Serial Data Communications: Notes
WARNING: This page is about a different car, the 1998 Cadillac Eldorado and 1998 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
DTC U1255 refers to a generic loss of serial data with an unknown module. DTC U1255 generally will set when vehicle is first started and A/C-heater programmer or CCP requests information from another module and does not get a response. DTC U1255 will clear when module communicates with A/C-heater programmer or CCP.