DTC U1255: Serial Data Line Malfunction: Description

Serial data circuit is used to communicate information between systems. Each system on the serial data line is assigned its own recognition code, which is used to identify which system is communicating. Systems periodically send a State of Health (SOH) message to other systems. If those systems fail to send an SOH message back, a corresponding DTC will be set. Also, any system that cannot communicate properly will set the corresponding DTC.

DTC U1255 will set when IPC detects an open or short in serial data line circuit for one second. No driver warning message will be displayed.

DTC U1255 requires an ignition cycle to change from current to his-tory. If conditions for malfunction no longer exist, history DTC will clear after 50 consecutive ignition cycles. DTC U1255 will also clear when conditions no longer exist, or when IPC or scan tool is used to clear codes.

NOTE: If DTC U1255 is a history code, problem may be intermittent. Wiggle wires while performing the following test.